TableModel::setData can now be called for column 0 with different roles to edit. (Doesn't rely on Qt::EditRole and RoleForColumn in all cases)

Basically like in this tutorial: https://doc.qt.io/qt-6/modelview.html#2-1-a-read-only-table

CMakeLists.txt

@@ -1,6 +1,7 @@
 cmake_minimum_required(VERSION 3.16)
 
-project(GenericCore LANGUAGES CXX)
+set(TARGET_APP "GenericCore")
+project(${TARGET_APP} VERSION 0.3.0 LANGUAGES CXX)
 
 set(CMAKE_AUTOUIC ON)
 set(CMAKE_AUTOMOC ON)
@@ -8,20 +9,45 @@ set(CMAKE_AUTORCC ON)
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
-find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Core LinguistTools)
+find_package(QT NAMES Qt6 REQUIRED COMPONENTS Core LinguistTools)
-find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Core LinguistTools)
+find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Core LinguistTools Gui)
+find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Test)
+find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Network)
 
-set(TS_FILES GenericCore_en_US.ts)
+configure_file(CoreConfig.h.in CoreConfig.h)
 
-add_library(GenericCore STATIC
+set(TS_FILES ${TARGET_APP}_en_US.ts)
+
+add_library(${TARGET_APP} STATIC
   genericcore.cpp
   genericcore.h
   ${TS_FILES}
+  constants.h
+  data/settingshandler.h data/settingshandler.cpp
+  model/tablemodel.h model/tablemodel.cpp
+  model/modelitem.h model/modelitem.cpp
+  formats/jsonparser.h formats/jsonparser.cpp
+  model/commands/insertrowscommand.h model/commands/insertrowscommand.cpp
+  model/commands/removerowscommand.h model/commands/removerowscommand.cpp
+  model/commands/edititemcommand.h model/commands/edititemcommand.cpp
+  data/filehandler.h data/filehandler.cpp
+  model/metadata.h
+  formats/csvparser.h formats/csvparser.cpp
+  model/generalsortfiltermodel.h model/generalsortfiltermodel.cpp
+  network/servercommunicator.h network/servercommunicator.cpp
+  network/apiroutes.h
+  # 3rd party libraries
+  ../3rdParty/rapidcsv/src/rapidcsv.h
+  utils/messagehandler.h
 )
 
-target_link_libraries(GenericCore PRIVATE Qt${QT_VERSION_MAJOR}::Core)
+include_directories(${CMAKE_CURRENT_BINARY_DIR})
 
-target_compile_definitions(GenericCore PRIVATE GENERICCORE_LIBRARY)
+target_link_libraries(${TARGET_APP} PRIVATE Qt${QT_VERSION_MAJOR}::Core Qt${QT_VERSION_MAJOR}::Gui)
+target_link_libraries(GenericCore PRIVATE Qt${QT_VERSION_MAJOR}::Test)
+target_link_libraries(GenericCore PRIVATE Qt${QT_VERSION_MAJOR}::Network)
+
+target_compile_definitions(${TARGET_APP} PRIVATE ${TARGET_APP}_LIBRARY)
 
 if(COMMAND qt_create_translation)
   qt_create_translation(QM_FILES ${CMAKE_SOURCE_DIR} ${TS_FILES})

CoreConfig.h.in

@@ -0,0 +1,2 @@
+#define CORE_NAME "${PROJECT_NAME}"
+#define CORE_VERSION "${PROJECT_VERSION}"

constants.h

@@ -0,0 +1,15 @@
+#ifndef CONSTANTS_H
+#define CONSTANTS_H
+
+#include <QString>
+
+/// Platform dependent
+#ifdef Q_OS_LINUX
+static const QString UPDATER_EXE = "maintenancetool";
+#elif defined(Q_OS_MAC)
+static const QString UPDATER_EXE = "maintenancetool.app/Contents/MacOS/maintenancetool";
+#elif defined(Q_OS_WIN)
+static const QString UPDATER_EXE = "maintenancetool.exe";
+#endif
+
+#endif  // CONSTANTS_H

data/filehandler.cpp

@@ -0,0 +1,89 @@
+#include "filehandler.h"
+
+#include <QDebug>
+#include <QDir>
+#include <QJsonDocument>
+#include <QStandardPaths>
+
+#include "../formats/csvparser.h"
+
+bool FileHandler::saveToFile(const QJsonDocument& doc, const QString& fileName) {
+  qDebug() << "saving file...";
+  QString path = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).at(0);
+  qDebug() << path;
+
+  QDir dir;
+  if (!dir.exists(path)) {
+    dir.mkpath(path);
+  }
+  //  qDebug() << path + fileName;
+  const QString filePath = path + '/' + fileName;
+  QFile file(filePath);
+
+  if (!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
+    qWarning() << "can't open file";
+    return false;
+  }
+  QTextStream out(&file);
+  out.setEncoding(QStringConverter::Utf8);
+  out << doc.toJson(QJsonDocument::Indented);
+  return true;
+}
+
+QByteArray FileHandler::loadJSONDataFromFile(const QString fileName) {
+  QFile file;
+  QString path = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).at(0);
+  file.setFileName(path + "/" + fileName);
+
+  QPair<QString, QByteArray> fileContent = getFileContent(path + "/" + fileName);
+
+  return fileContent.second;
+}
+
+QList<ModelItemValues> FileHandler::getItemValuesFromCSVFile(const QString& filePath) {
+  QList<ModelItemValues> result;
+  QFile file;
+  file.setFileName(filePath);
+  if (file.exists()) {
+    result = CsvParser::getItemsFromCSVFile(filePath);
+  }
+  return result;
+}
+
+bool FileHandler::exportToCSVFile(const QList<QStringList>& rows, const QString& filePath) {
+  return CsvParser::exportToCSVFile(rows, filePath);
+}
+
+FileHandler::FileHandler() {}
+
+/** Tries to open the file specified by the file path & returns the content
+ * @brief FileHandler::getFileContent
+ * @param filePath
+ * @return Returns an error string (empty if successful) and the file content
+ */
+QPair<QString, QByteArray> FileHandler::getFileContent(const QString& filePath) {
+  QString errorString = "";
+
+  QByteArray fileContent;
+  QFile file;
+  file.setFileName(filePath);
+  if (file.exists()) {
+    qDebug() << "File found, reading content...";
+    const bool successfulOpened = file.open(QIODevice::ReadOnly | QIODevice::Text);
+    if (successfulOpened) {
+      // TODO learn and decide on the differences between "readAll" and using
+      // streams
+      fileContent = file.readAll();
+      file.close();
+    } else {
+      errorString = "File could not be opened!";
+      qWarning() << errorString;
+    }
+  } else {
+    errorString = "File not found. Returning empty result...";
+    qInfo() << errorString;
+  }
+
+  const QPair<QString, QByteArray> result(errorString, fileContent);
+  return result;
+}

data/filehandler.h

@@ -0,0 +1,28 @@
+#ifndef FILEHANDLER_H
+#define FILEHANDLER_H
+
+#include <QVariant>
+
+typedef QMap<int, QVariant> ModelItemValues;
+
+class QJsonDocument;
+class QString;
+class QByteArray;
+
+class FileHandler {
+ public:
+  /// JSON
+  static bool saveToFile(const QJsonDocument& doc, const QString& fileName);
+  static QByteArray loadJSONDataFromFile(const QString fileName);
+
+  /// CSV
+  static QList<ModelItemValues> getItemValuesFromCSVFile(const QString& filePath);
+  static bool exportToCSVFile(const QList<QStringList>& rows, const QString& filePath);
+
+ private:
+  explicit FileHandler();
+
+  static QPair<QString, QByteArray> getFileContent(const QString& filePath);
+};
+
+#endif  // FILEHANDLER_H

data/settingshandler.cpp

@@ -0,0 +1,43 @@
+#include "settingshandler.h"
+
+#include <QSettings>
+
+QVariantMap SettingsHandler::getSettings(QString group) {
+  QSettings settings;
+  QVariantMap result;
+
+  if (!group.isEmpty()) {
+    settings.beginGroup(group);
+  }
+
+  foreach (QString key, settings.allKeys()) {
+    result.insert(key, settings.value(key));
+  }
+
+  if (!group.isEmpty()) {
+    settings.endGroup();
+  }
+
+  return result;
+}
+
+void SettingsHandler::saveSettings(QVariantMap settingMap, QString group) {
+  qInfo() << "saving settings...";
+
+  QSettings settings;
+  if (!group.isEmpty()) {
+    settings.beginGroup(group);
+  }
+
+  foreach (QString key, settingMap.keys()) {
+    //    qDebug() << "saving:" << key << "-" << settingMap.value(key);
+    settings.setValue(key, settingMap.value(key));
+  }
+  if (!group.isEmpty()) {
+    settings.endGroup();
+  }
+
+  settings.sync();
+}
+
+SettingsHandler::SettingsHandler() {}

data/settingshandler.h

@@ -0,0 +1,15 @@
+#ifndef SETTINGSHANDLER_H
+#define SETTINGSHANDLER_H
+
+#include <QVariantMap>
+
+class SettingsHandler {
+ public:
+  static QVariantMap getSettings(QString group = "");
+  static void saveSettings(QVariantMap settingMap, QString group = "");
+
+ private:
+  SettingsHandler();
+};
+
+#endif  // SETTINGSHANDLER_H

formats/csvparser.cpp

@@ -0,0 +1,162 @@
+#include "csvparser.h"
+
+#include <QHash>
+#include <QLocale>
+#include <QVariant>
+
+#include "../../3rdParty/rapidcsv/src/rapidcsv.h"
+#include "../model/metadata.h"
+
+using namespace rapidcsv;
+
+QList<ModelItemValues> CsvParser::getItemsFromCSVFile(const QString& fileName) {
+  Document doc(fileName.toStdString());
+
+  const bool isCompatible = isCsvCompatible(doc);
+  if (isCompatible) {
+    const QList<ModelItemValues> result = createListItemsFromCsvEntries(doc);
+    return result;
+  } else {
+    return QList<ModelItemValues>();
+  }
+}
+
+bool CsvParser::exportToCSVFile(const QList<QStringList>& rows, const QString& filePath) {
+  Document doc(std::string(), LabelParams(0, -1));
+  const QList<QString> headerNames = GET_HEADER_NAMES();
+  for (int column = 0; column < headerNames.size(); ++column) {
+    doc.SetColumnName(column, headerNames.at(column).toStdString());
+  }
+  for (int row = 0; row < rows.size(); ++row) {
+    QStringList rowValues = rows.at(row);
+    std::vector<std::string> rowValueStrings;
+    for (int column = 0; column < rowValues.size(); ++column) {
+      rowValueStrings.push_back(rowValues.at(column).toStdString());
+    }
+    doc.InsertRow(row, rowValueStrings);
+  }
+  doc.Save(filePath.toStdString());
+  return true;
+}
+
+CsvParser::CsvParser() {}
+
+/** A CSV file is compatible if the following is true:
+ *  - there is a CSV column for every column in the table model
+ *  (except there are optional columns defined in the model)
+ * @brief CsvParser::isCsvCompatible
+ * @param doc
+ * @return
+ */
+bool CsvParser::isCsvCompatible(const rapidcsv::Document& doc) {
+  qInfo() << "Checking CSV document for compatiblity...";
+  const std::vector<std::string> columnNames = doc.GetColumnNames();
+  for (const QString& headerName : GET_HEADER_NAMES()) {
+    bool isHeaderNameFound = false;
+    if (std::find(columnNames.begin(), columnNames.end(), headerName) != columnNames.end()) {
+      qDebug() << QString("Header found in column names: %1").arg(headerName);
+    } else {
+      const QString errorString =
+          QString("Couldn't find header name '%1' in CSV file. Aborting...").arg(headerName);
+      qWarning() << errorString;
+      return false;
+    }
+  }
+  return true;
+}
+
+QList<ModelItemValues> CsvParser::createListItemsFromCsvEntries(const rapidcsv::Document& doc) {
+  QList<ModelItemValues> result;
+  const int rowCount               = doc.GetRowCount();
+  const QList<QString> headerNames = GET_HEADER_NAMES();
+
+  /// get the values for all columns
+  QHash<QString, std::vector<std::string>> columnValueMap = extractColumnValues(headerNames, doc);
+
+  /// get item values for each row
+  for (int row = 0; row < rowCount; ++row) {
+    const ModelItemValues itemValues = getItemValuesForRow(headerNames, columnValueMap, row);
+    result.append(itemValues);
+  }
+  return result;
+}
+
+QHash<QString, std::vector<std::string>> CsvParser::extractColumnValues(
+    const QList<QString> headerNames,
+    const rapidcsv::Document& doc) {
+  QHash<QString, std::vector<std::string>> columnValueMap;
+  for (const QString& columnName : headerNames) {
+    // TODO add support for optional columns
+    // if (optionalCsvHeaderNames.contains(columnName)) {
+    //   const std::vector<std::string> columnNames = doc.GetColumnNames();
+    //   int columnIdx                              = doc.GetColumnIdx(columnName.toStdString());
+    //   if (columnIdx == -1) {
+    //     continue;
+    //   }
+    // }
+    const std::vector<std::string> columnValues =
+        doc.GetColumn<std::string>(columnName.toStdString());
+    columnValueMap.insert(columnName, columnValues);
+  }
+
+  return columnValueMap;
+}
+
+ModelItemValues CsvParser::getItemValuesForRow(
+    const QList<QString>& headerNames,
+    const QHash<QString, std::vector<std::string>>& columnValueMap,
+    const int row) {
+  ModelItemValues result;
+  for (const QString& columnName : headerNames) {
+    if (!columnValueMap.contains(columnName)) {
+      continue;
+    }
+    int role                = ROLE_NAMES.key(columnName.toLatin1());
+    std::string valueString = columnValueMap.value(columnName).at(row);
+
+    QVariant value = parseItemValue(role, valueString);
+    if (value.isValid()) {
+      result[role] = value;
+    }
+  }
+  return result;
+}
+
+QVariant CsvParser::parseItemValue(const int role, const std::string& valueString) {
+  QVariant result;
+  if (STRING_ROLES.contains(role)) {
+    /// string values
+    result = QString::fromStdString(valueString);
+  } else if (TYPE_ROLES.contains(role)) {
+    /// type values
+    // TODO validate string is allowed
+    result = QString::fromStdString(valueString);
+  } else if (INT_ROLES.contains(role)) {
+    /// int values
+
+    /// GetColumn<int> crashed (probably because of the empty values)
+    /// so the strings will be processed later
+    const QString intAsString = QString::fromStdString(valueString);
+    result                    = intAsString.toInt();
+  } else if (DOUBLE_ROLES.contains(role)) {
+    /// double values
+    const QString doubleAsString = QString::fromStdString(valueString);
+    double doubleValue;
+    if (doubleAsString.contains(',')) {
+      QLocale german(QLocale::German);
+      doubleValue = german.toDouble(doubleAsString);
+    } else {
+      doubleValue = doubleAsString.toDouble();
+    }
+    result = doubleValue;
+
+    // } else if (typeColumns.contains(columnName)) {
+    //   // TODO validate string is allowed
+    //   values[role] = QString::fromStdString(columnValueMap.value(columnName).at(row));
+  } else {
+    /// no type recognized for column
+    QString errorString = QString("Couldn't find value type for role '%1'").arg(role);
+    qCritical() << errorString;
+  }
+  return result;
+}

formats/csvparser.h

@@ -0,0 +1,32 @@
+#ifndef CSVPARSER_H
+#define CSVPARSER_H
+
+#include <QString>
+
+typedef QMap<int, QVariant> ModelItemValues;
+
+namespace rapidcsv {
+class Document;
+}
+
+class CsvParser {
+ public:
+  static QList<ModelItemValues> getItemsFromCSVFile(const QString& fileName);
+  static bool exportToCSVFile(const QList<QStringList>& rows, const QString& filePath);
+
+ private:
+  explicit CsvParser();
+
+  static bool isCsvCompatible(const rapidcsv::Document& doc);
+  static QList<ModelItemValues> createListItemsFromCsvEntries(const rapidcsv::Document& doc);
+  static QHash<QString, std::vector<std::string>> extractColumnValues(
+      const QList<QString> headerNames,
+      const rapidcsv::Document& doc);
+  static ModelItemValues getItemValuesForRow(
+      const QList<QString>& headerNames,
+      const QHash<QString, std::vector<std::string>>& columnValueMap,
+      const int row);
+  static QVariant parseItemValue(const int role, const std::string& valueString);
+};
+
+#endif  // CSVPARSER_H

formats/jsonparser.cpp

@@ -0,0 +1,143 @@
+#include "jsonparser.h"
+
+#include <QJsonArray>
+#include <QJsonObject>
+
+#include "../model/metadata.h"
+
+QList<ModelItemValues> JsonParser::toItemValuesList(const QByteArray& jsonData,
+                                                    const QString& rootValueName) {
+  QList<ModelItemValues> result;
+
+  if (jsonData.isEmpty()) {
+    return result;
+  }
+  // TODO tidy up the following code and encapsulate into functions;
+
+  QJsonDocument doc = QJsonDocument::fromJson(jsonData);
+
+  /// case one: json value name in plural -> should contain an array of items
+  if (rootValueName == ITEMS_KEY_STRING) {
+    QJsonArray itemArray = extractItemArray(doc, rootValueName);
+
+    foreach (QJsonValue value, itemArray) {
+      QJsonObject itemJsonObject = value.toObject();
+      ModelItemValues values     = jsonObjectToItemValues(itemJsonObject);
+      result.append(values);
+    }
+  }
+  /// case two: json value name in singular -> should contain an object of one item
+  if (rootValueName == ITEM_KEY_STRING) {
+    QJsonObject rootObject     = doc.object();
+    QJsonObject itemJsonObject = rootObject.value(rootValueName).toObject();
+    ModelItemValues values     = jsonObjectToItemValues(itemJsonObject);
+    result.append(values);
+  }
+
+  return result;
+}
+
+QByteArray JsonParser::itemValuesListToJson(const QList<ModelItemValues>& itemValuesList,
+                                            const QString& objectName) {
+  QJsonDocument jsonDoc;
+  QJsonObject rootObject;
+  QJsonArray itemArray;
+  for (const ModelItemValues& itemValues : itemValuesList) {
+    QJsonObject itemObject = itemValuesToJsonObject(itemValues);
+    itemArray.append(itemObject);
+  }
+
+  rootObject.insert(objectName, itemArray);
+  jsonDoc.setObject(rootObject);
+
+  return jsonDoc.toJson(QJsonDocument::Compact);
+}
+
+QJsonObject JsonParser::itemValuesToJsonObject(const ModelItemValues& itemValues) {
+  QJsonObject result;
+
+  // TODO add dates (entry, modification, end)
+  const UserRoles idRole   = IdRole;
+  const QJsonValue idValue = extractJsonValue(itemValues, idRole);
+  if (!idValue.isNull()) {
+    const QString idRoleName = ROLE_NAMES.value(idRole);
+    result.insert(idRoleName, idValue);
+  }
+
+  QListIterator<UserRoles> i(USER_FACING_ROLES);
+  while (i.hasNext()) {
+    const UserRoles role       = i.next();
+    const QJsonValue jsonValue = extractJsonValue(itemValues, role);
+    const QString roleName     = ROLE_NAMES.value(role);
+    result.insert(roleName, jsonValue);
+  }
+  return result;
+}
+
+JsonParser::JsonParser() {}
+
+QJsonArray JsonParser::extractItemArray(const QJsonDocument& doc, const QString& objectName) {
+  QJsonArray itemArray;
+  if (objectName.isEmpty()) {
+    itemArray = doc.array();
+  } else {
+    QJsonObject rootObject = doc.object();
+    itemArray              = rootObject.value(objectName).toArray();
+  }
+  return itemArray;
+}
+
+ModelItemValues JsonParser::jsonObjectToItemValues(const QJsonObject& itemJsonObject) {
+  ModelItemValues values;
+
+  const UserRoles idRole   = IdRole;
+  const QString idRoleName = ROLE_NAMES.value(idRole);
+  // QVariant idValue         = data(idRole);
+  if (itemJsonObject.contains(idRoleName)) {
+    std::pair<int, QVariant> keyValuePair = getKeyValuePair(itemJsonObject, idRole);
+    values.insert(keyValuePair.first, keyValuePair.second);
+  }
+
+  QListIterator<UserRoles> i(USER_FACING_ROLES);
+  while (i.hasNext()) {
+    const UserRoles role                  = i.next();
+    std::pair<int, QVariant> keyValuePair = getKeyValuePair(itemJsonObject, role);
+    values.insert(keyValuePair.first, keyValuePair.second);
+  }
+  return values;
+}
+
+pair<int, QVariant> JsonParser::getKeyValuePair(const QJsonObject& itemJsonObject, const int role) {
+  QVariant result;
+  const QJsonValue jsonValue = itemJsonObject[ROLE_NAMES.value(role)];
+  if (STRING_ROLES.contains(role)) {
+    result = jsonValue.toString();
+  } else if (INT_ROLES.contains(role)) {
+    result = jsonValue.toInt();
+  } else if (DOUBLE_ROLES.contains(role)) {
+    result = jsonValue.toDouble();
+  } else if (TYPE_ROLES.contains(role)) {
+    result = jsonValue.toString();
+  } else {
+    qCritical() << QString("Cant find data type of role %1!!!").arg(role);
+  }
+  return pair<int, QVariant>(role, result);
+}
+
+QJsonValue JsonParser::extractJsonValue(const ModelItemValues& itemValues, const int role) {
+  QJsonValue result;
+  const QString roleName = ROLE_NAMES.value(role);
+  const QVariant value   = itemValues.value(role);
+  if (STRING_ROLES.contains(role)) {
+    result = value.toString();
+  } else if (INT_ROLES.contains(role)) {
+    result = value.toInt();
+  } else if (DOUBLE_ROLES.contains(role)) {
+    result = value.toDouble();
+  } else if (TYPE_ROLES.contains(role)) {
+    result = value.toString();
+  } else {
+    qCritical() << QString("Can't find data type for role %1!!!").arg(role);
+  }
+  return result;
+}

formats/jsonparser.h

@@ -0,0 +1,34 @@
+#ifndef JSONPARSER_H
+#define JSONPARSER_H
+
+#include <QVariant>
+
+class QJsonObject;
+class QString;
+class QByteArray;
+class QJsonArray;
+
+typedef QMap<int, QVariant> ModelItemValues;
+
+using namespace std;
+
+class JsonParser {
+ public:
+  static QList<ModelItemValues> toItemValuesList(const QByteArray& jsonData,
+                                                 const QString& rootValueName = "");
+  static QByteArray itemValuesListToJson(const QList<ModelItemValues>& itemValuesList,
+                                         const QString& objectName = "");
+  static QJsonObject itemValuesToJsonObject(const ModelItemValues& itemValues);
+
+ private:
+  explicit JsonParser();
+
+  static QJsonArray extractItemArray(const QJsonDocument& doc, const QString& objectName);
+  static ModelItemValues jsonObjectToItemValues(const QJsonObject& itemJsonObject);
+
+  static pair<int, QVariant> getKeyValuePair(const QJsonObject& itemJsonObject, const int role);
+
+  static QJsonValue extractJsonValue(const ModelItemValues& itemValues, const int role);
+};
+
+#endif  // JSONPARSER_H

genericcore.cpp

@@ -1,3 +1,281 @@
 #include "genericcore.h"
 
-GenericCore::GenericCore() {}
+#include <QAbstractItemModelTester>
+#include <QCoreApplication>
+#include <QDateTime>
+#include <QDebug>
+#include <QJsonDocument>
+#include <QProcess>
+#include <QSettings>
+#include <QString>
+
+#include "../../ApplicationConfig.h"
+#include "CoreConfig.h"
+#include "constants.h"
+#include "data/filehandler.h"
+#include "data/settingshandler.h"
+#include "model/generalsortfiltermodel.h"
+#include "model/metadata.h"
+#include "model/tablemodel.h"
+#include "network/servercommunicator.h"
+
+#include <QtGui/QUndoStack>
+
+using namespace std;
+
+GenericCore::GenericCore() {
+  qDebug() << "Creating core...";
+
+  QCoreApplication::setOrganizationName("Working-Copy Collective");
+  QCoreApplication::setOrganizationDomain("working-copy.org");
+
+#ifdef QT_DEBUG
+  QCoreApplication::setApplicationName(QString(APPLICATION_NAME) + "-dev");
+#else
+  QCoreApplication::setApplicationName(QString(APPLICATION_NAME));
+#endif
+
+  // TODO let the model own its undo stack (& use TableModel::getUndoStack() if necessary)
+  m_modelUndoStack = new QUndoStack(this);
+
+  setupModels();
+  setupServerConfiguration();
+}
+
+GenericCore::~GenericCore() { qDebug() << "Destroying core..."; }
+
+QString GenericCore::toString() const {
+  return QString("%1 (Version %2)").arg(CORE_NAME).arg(CORE_VERSION);
+}
+
+void GenericCore::sayHello() const { qDebug() << "Hello from the core!"; }
+
+bool GenericCore::isApplicationUpdateAvailable() {
+  QProcess process;
+  const QString programmString = getMaintenanceToolFilePath();
+  const QStringList checkArgs("--checkupdates");
+  process.start(programmString, checkArgs);
+  process.waitForFinished();
+
+  const int exitCode = process.exitCode();
+  if (process.error() != QProcess::UnknownError) {
+    qDebug() << "Error checking for updates";
+    emit displayStatusMessage("Error checking for updates");
+    return false;
+  }
+
+  QByteArray data = process.readAllStandardOutput();
+
+  QSettings settings;
+  settings.beginGroup("Application");
+  settings.setValue("lastCheckForUpdate", QDateTime::currentDateTimeUtc());
+  settings.endGroup();
+  settings.sync();
+
+  if (data.isEmpty() || data.contains("currently no updates")) {
+    qInfo() << "No updates available";
+    emit displayStatusMessage("No updates available.");
+    return false;
+  }
+
+  return true;
+}
+
+void GenericCore::triggerApplicationUpdate(const bool saveChanges) {
+  if (saveChanges && !m_modelUndoStack->isClean()) {
+    saveItems();
+  }
+  QStringList args("--start-updater");
+  QString toolFilePath = getMaintenanceToolFilePath();
+  QProcess::startDetached(toolFilePath, args);
+}
+
+QUndoStack* GenericCore::getModelUndoStack() const { return m_modelUndoStack; }
+
+std::shared_ptr<TableModel> GenericCore::getModel() const { return m_mainModel; }
+
+std::shared_ptr<GeneralSortFilterModel> GenericCore::getSortFilterModel() const {
+  return m_sortFilterModel;
+}
+
+/**
+ * Save items to default file (in standard location).
+ * @brief GenericCore::saveItems Saves item fo file.
+ */
+void GenericCore::saveItems() {
+  qDebug() << "saving items...";
+
+  const QJsonDocument doc   = m_mainModel->getAllItemsAsJsonDoc();
+  const bool successfulSave = FileHandler::saveToFile(doc, ITEMS_FILE_NAME);
+  if (successfulSave) {
+    m_modelUndoStack->setClean();
+    emit displayStatusMessage(QString("Items saved."));
+  } else {
+    emit displayStatusMessage(QString("Error: Items couldn't be saved."));
+  }
+}
+
+void GenericCore::importCSVFile(const QString& filePath) {
+  qInfo() << "importing items from CSV...";
+  qDebug() << "filePath:" << filePath;
+  const QList<ModelItemValues> itemValuesList = FileHandler::getItemValuesFromCSVFile(filePath);
+  // TODO inform UI on errors
+  if (itemValuesList.isEmpty()) {
+    qDebug() << "No items found. Doing nothing...";
+    return;
+  }
+  // qDebug() << "CSV file content:" << itemValuesList;
+  m_mainModel->insertItems(m_mainModel->rowCount(), itemValuesList);
+}
+
+bool GenericCore::exportCSVFile(const QString& filePath) {
+  qInfo() << "exporting items to CSV...";
+  qDebug() << "filePath:" << filePath;
+  const QList<QStringList> itemsAsStringLists = m_mainModel->getItemsAsStringLists();
+  return FileHandler::exportToCSVFile(itemsAsStringLists, filePath);
+}
+
+QVariantMap GenericCore::getSettings(QString group) const {
+  return SettingsHandler::getSettings(group);
+}
+
+void GenericCore::applySettings(QVariantMap settingMap, QString group) {
+  SettingsHandler::saveSettings(settingMap, group);
+
+  if (group == "Server") {
+    setupServerConfiguration();
+  }
+}
+
+bool GenericCore::isSyncServerSetup() const {
+  if (m_serverCommunicator) {
+    return true;
+  } else {
+    return false;
+  }
+}
+
+void GenericCore::onSendItemTriggered(const QByteArray& jsonData) {
+  m_serverCommunicator->postItems(jsonData);
+}
+
+void GenericCore::onItemsFetched(const QByteArray jsonData) {
+  emit displayStatusMessage("New items fetched.");
+  // TODO ? check compability of JSON structure beforehand?
+  // NEXT check if item already exists and apply changes (UUID,...) ? ;
+  m_mainModel->appendItems(jsonData);
+}
+
+void GenericCore::onItemsFetchFailure(const QString errorString) {
+  emit displayStatusMessage(QString("Error: %1").arg(errorString));
+}
+
+void GenericCore::onPostRequestSuccessful(const QByteArray responseData) {
+  const QString message = m_mainModel->updateItemsFromJson(responseData);
+  emit displayStatusMessage(message);
+}
+
+void GenericCore::onPostRequestFailure(const QString errorString) {
+  emit displayStatusMessage(QString("Error: %1").arg(errorString));
+}
+
+void GenericCore::onDeleteRequestSuccessful(const QByteArray responseData) {
+  qWarning() << "TODO: Process success response!!!";
+}
+
+void GenericCore::onDeleteRequestFailure(const QString errorString) {
+  qWarning() << "TODO: Process error response!!!";
+}
+
+void GenericCore::setupModels() {
+  m_mainModel       = make_shared<TableModel>(m_modelUndoStack, this);
+  m_sortFilterModel = make_shared<GeneralSortFilterModel>(m_mainModel);
+
+  /// QAbstractItemModelTester
+#ifdef QT_DEBUG
+  m_mainModelTester = make_unique<QAbstractItemModelTester>(
+      m_mainModel.get(), QAbstractItemModelTester::FailureReportingMode::Fatal);
+  m_proxyModelTester = make_unique<QAbstractItemModelTester>(
+      m_sortFilterModel.get(), QAbstractItemModelTester::FailureReportingMode::Fatal);
+#else
+  m_mainModelTester = make_unique<QAbstractItemModelTester>(
+      m_mainModel.get(), QAbstractItemModelTester::FailureReportingMode::Warning);
+  m_proxyModelTester = make_unique<QAbstractItemModelTester>(
+      m_sortFilterModel.get(), QAbstractItemModelTester::FailureReportingMode::Warning);
+#endif
+
+  initModelData();
+}
+
+/**
+ * Initializing model with data. Tries to read items from default file. Generating example items as
+ * fallback.
+ * @brief GenericCore::initModelData
+ */
+void GenericCore::initModelData() {
+  qInfo() << "Trying to read model data from file...";
+  const QByteArray jsonDoc = FileHandler::loadJSONDataFromFile(ITEMS_FILE_NAME);
+  // qDebug() << "jsonDoc:" << jsonDoc;
+  // TODO decide on lack of file(s) (config, data) if example items should be generated
+  //      (see welcome wizard)
+  if (jsonDoc.isEmpty()) {
+    qDebug() << "No item content in file. Generating example items...";
+    const QByteArray exampleItems = m_mainModel->generateExampleItems();
+    m_mainModel->insertItems(0, exampleItems);
+  } else {
+    qDebug() << "Item in file found.";
+    m_mainModel->insertItems(0, jsonDoc);
+  }
+  m_modelUndoStack->clear();
+}
+
+QString GenericCore::getMaintenanceToolFilePath() const {
+  QString applicationDirPath = QCoreApplication::applicationDirPath();
+
+/// setting the applicationDirPath hard coded to test update feature from IDE
+#ifdef QT_DEBUG
+  applicationDirPath = QString("/opt/%1").arg(APPLICATION_NAME);
+#endif
+
+#ifdef Q_OS_MAC
+  applicationDirPath.append("/../../..");
+#endif
+  const QString filePath = applicationDirPath + "/" + UPDATER_EXE;
+  return filePath;
+}
+
+void GenericCore::setupServerConfiguration() {
+  m_serverCommunicator = make_unique<ServerCommunicator>(this);
+  /// request connections
+  connect(this, &GenericCore::fetchItemsFromServer, m_serverCommunicator.get(),
+          &ServerCommunicator::fetchItems);
+  connect(this, &GenericCore::postItemToServer, this, &GenericCore::onSendItemTriggered);
+  connect(this, &GenericCore::deleteItemFromServer, m_serverCommunicator.get(),
+          &ServerCommunicator::deleteItem);
+
+  /// response connections
+  connect(m_serverCommunicator.get(), &ServerCommunicator::itemsFetched, this,
+          &GenericCore::onItemsFetched);
+  connect(m_serverCommunicator.get(), &ServerCommunicator::itemsFetchFailure, this,
+          &GenericCore::onItemsFetchFailure);
+  connect(m_serverCommunicator.get(), &ServerCommunicator::postRequestSuccessful, this,
+          &GenericCore::onPostRequestSuccessful);
+  connect(m_serverCommunicator.get(), &ServerCommunicator::postRequestFailure, this,
+          &GenericCore::onPostRequestFailure);
+  connect(m_serverCommunicator.get(), &ServerCommunicator::deleteRequestSuccessful, this,
+          &GenericCore::onDeleteRequestSuccessful);
+  connect(m_serverCommunicator.get(), &ServerCommunicator::deleteRequestFailure, this,
+          &GenericCore::onDeleteRequestFailure);
+
+  applyServerConfiguration();
+}
+
+void GenericCore::applyServerConfiguration() {
+  const QVariantMap serverSettings = SettingsHandler::getSettings("Server");
+  const QString urlValue           = serverSettings.value("url").toString();
+  if (!urlValue.isEmpty()) {
+    const QString emailValue    = serverSettings.value("email").toString();
+    const QString passwordValue = serverSettings.value("password").toString();
+    m_serverCommunicator->setServerConfiguration(urlValue, emailValue, passwordValue);
+  }
+}

genericcore.h

@@ -1,10 +1,73 @@
 #ifndef GENERICCORE_H
 #define GENERICCORE_H
 
-class GenericCore
+#include <QObject>
-{
+
-public:
+class QUndoStack;
+class QAbstractItemModel;
+class QAbstractItemModelTester;
+class QString;
+
+class TableModel;
+class GeneralSortFilterModel;
+class ServerCommunicator;
+
+class GenericCore : public QObject {
+  Q_OBJECT
+
+ public:
   GenericCore();
+  ~GenericCore();
+
+  QString toString() const;
+  void sayHello() const;
+
+  bool isApplicationUpdateAvailable();
+  void triggerApplicationUpdate(const bool saveChanges);
+
+  QUndoStack* getModelUndoStack() const;
+  std::shared_ptr<TableModel> getModel() const;
+  std::shared_ptr<GeneralSortFilterModel> getSortFilterModel() const;
+
+  void saveItems();
+  void importCSVFile(const QString& filePath);
+  bool exportCSVFile(const QString& filePath);
+
+  QVariantMap getSettings(QString group = "") const;
+  void applySettings(QVariantMap settingMap, QString group = "");
+  bool isSyncServerSetup() const;
+
+ public slots:
+  void onSendItemTriggered(const QByteArray& jsonData);
+  void onItemsFetched(const QByteArray jsonData);
+  void onItemsFetchFailure(const QString errorString);
+  void onPostRequestSuccessful(const QByteArray responseData);
+  void onPostRequestFailure(const QString errorString);
+  void onDeleteRequestSuccessful(const QByteArray responseData);
+  void onDeleteRequestFailure(const QString errorString);
+
+ signals:
+  void displayStatusMessage(QString message);
+  void fetchItemsFromServer();
+  void postItemToServer(const QByteArray& jsonData);
+  void deleteItemFromServer(const QString& id);
+
+ private:
+  QUndoStack* m_modelUndoStack;
+  std::shared_ptr<TableModel> m_mainModel;
+  std::shared_ptr<GeneralSortFilterModel> m_sortFilterModel;
+  std::unique_ptr<QAbstractItemModelTester> m_mainModelTester;
+  std::unique_ptr<QAbstractItemModelTester> m_proxyModelTester;
+
+  void setupModels();
+  void initModelData();
+
+  QString getMaintenanceToolFilePath() const;
+
+  /// Network communication
+  std::unique_ptr<ServerCommunicator> m_serverCommunicator;
+  void setupServerConfiguration();
+  void applyServerConfiguration();
 };
 
 #endif  // GENERICCORE_H

model/commands/edititemcommand.cpp

@@ -0,0 +1,80 @@
+#include "edititemcommand.h"
+
+#include <QDebug>
+
+#include "../metadata.h"
+#include "../tablemodel.h"
+
+EditItemCommand::EditItemCommand(TableModel* model,
+                                 const QModelIndex& index,
+                                 QMap<int, QVariant>& changedValues,
+                                 QUndoCommand* parent)
+    : QUndoCommand(parent)
+    , m_model(model)
+    , m_row(index.row()) {
+  qInfo() << "New EditCommand...";
+  QString commandText;
+
+  if (changedValues.size() == 1) {
+    qDebug() << "Only one value to change. Using more specific command text...";
+    const int role       = changedValues.firstKey();
+    const QVariant value = changedValues.first();
+    QString roleName     = model->roleNames().value(role);
+
+    if (USER_FACING_ROLES.contains(role)) {
+      commandText = QString("Setting '%1' of item '%2' to '%3'")
+                        .arg(roleName)
+                        .arg(index.data(DEFAULT_ROLE).toString())
+                        .arg(value.toString());
+    } else if (role == IdRole) {
+      commandText = QString("Setting '%1' of item '%2' to '%3'")
+                        .arg(roleName)
+                        .arg(index.data(DEFAULT_ROLE).toString())
+                        .arg(value.toString());
+    } else {
+      qWarning() << "Role didn't match! Using a generic command text...";
+      commandText = QString("Edit item '%1'").arg(index.data(DEFAULT_ROLE).toString());
+    }
+  } else {
+    qDebug() << "More than one value to change. Using a generic command text...";
+    commandText = QString("Edit item '%1'").arg(index.data(DEFAULT_ROLE).toString());
+  }
+  setText(commandText);
+
+  m_newValues = changedValues;
+
+  /// storing old values for undo step
+  m_oldValues = getOldValues(index, changedValues);
+}
+
+void EditItemCommand::undo() {
+  qDebug() << "Undoing the EditCommand...";
+  m_model->execEditItemData(m_row, m_oldValues);
+}
+
+void EditItemCommand::redo() {
+  qDebug() << "(Re-)doing the EditCommand...";
+  m_model->execEditItemData(m_row, m_newValues);
+}
+
+const QMap<int, QVariant> EditItemCommand::getOldValues(
+    const QModelIndex& index,
+    const QMap<int, QVariant>& changedValues) const {
+  QMap<int, QVariant> result;
+  QMap<int, QVariant>::const_iterator i;
+  for (i = changedValues.constBegin(); i != changedValues.constEnd(); ++i) {
+    const int role          = i.key();
+    const QVariant newValue = i.value();
+    const QVariant oldValue = index.data(role);
+    // TODO check if role is a editable role?
+    if (oldValue != newValue) {
+      qDebug() << "oldValue:" << oldValue << "!= newValue:" << newValue;
+      result.insert(role, oldValue);
+    } else {
+      qInfo() << "oldValue is already the same as newValue:" << oldValue;
+    }
+  }
+  // QVariant oldModifiedDate = index.data(ModifiedDateUTCRole);
+  // result.insert(ModifiedDateUTCRole, oldModifiedDate);
+  return result;
+}

model/commands/edititemcommand.h

@@ -0,0 +1,33 @@
+#ifndef EDITITEMCOMMAND_H
+#define EDITITEMCOMMAND_H
+
+#include <QMap>
+#include <QUndoCommand>
+
+class TableModel;
+
+class EditItemCommand : public QUndoCommand {
+ public:
+  // TODO don't use simple pointer to model
+  /// Using simple pointer to model because there was a crash when closing the application with an
+  /// unclean undo stack
+  EditItemCommand(TableModel* model,
+                  const QModelIndex& index,
+                  QMap<int, QVariant>& changedValues,
+                  QUndoCommand* parent = nullptr);
+  /// QUndoCommand interface
+  void undo();
+  void redo();
+
+ private:
+  TableModel* m_model = nullptr;
+  const int m_row;
+  QMap<int, QVariant> m_oldValues;
+  QMap<int, QVariant> m_newValues;
+
+  /// private functions
+  const QMap<int, QVariant> getOldValues(const QModelIndex& index,
+                                         const QMap<int, QVariant>& changedValues) const;
+};
+
+#endif  // EDITITEMCOMMAND_H

model/commands/insertrowscommand.cpp

@@ -0,0 +1,33 @@
+#include "insertrowscommand.h"
+
+#include <QDebug>
+
+#include "../tablemodel.h"
+
+InsertRowsCommand::InsertRowsCommand(TableModel* model,
+                                     int startRow,
+                                     QList<ModelItemValues> valueList,
+                                     QUndoCommand* parent)
+    : QUndoCommand(parent)
+    , m_tableModel(model)
+    , m_startRow(startRow)
+    , m_valueList(valueList) {
+  qInfo() << "New InsertCommand...";
+  const QString commandText =
+      QString("inserting %1 item(s) on row %2").arg(valueList.length()).arg(startRow);
+  setText(commandText);
+}
+
+void InsertRowsCommand::undo() {
+  qDebug() << "Undoing the InsertCommand...";
+  if (m_tableModel) {
+    m_tableModel->execRemoveItems(m_startRow, m_valueList.length());
+  }
+}
+
+void InsertRowsCommand::redo() {
+  qDebug() << "(Re-)doing the InsertCommand...";
+  if (m_tableModel) {
+    m_tableModel->execInsertItems(m_startRow, m_valueList);
+  }
+}

model/commands/insertrowscommand.h

@@ -0,0 +1,30 @@
+#ifndef INSERTROWSCOMMAND_H
+#define INSERTROWSCOMMAND_H
+
+#include <QUndoCommand>
+
+typedef QMap<int, QVariant> ModelItemValues;
+
+class TableModel;
+
+class InsertRowsCommand : public QUndoCommand {
+ public:
+  // TODO don't use simple pointer to model
+  /// Using simple pointer to model because there was a crash when closing the application with an
+  /// unclean undo stack
+  InsertRowsCommand(TableModel* model,
+                    int startRow,
+                    QList<ModelItemValues> valueList,
+                    QUndoCommand* parent = nullptr);
+
+  /// QUndoCommand interface
+  void undo() override;
+  void redo() override;
+
+ private:
+  TableModel* m_tableModel;
+  const int m_startRow;
+  const QList<ModelItemValues> m_valueList;
+};
+
+#endif  // INSERTROWSCOMMAND_H

model/commands/removerowscommand.cpp

@@ -0,0 +1,41 @@
+#include "removerowscommand.h"
+
+#include <QDebug>
+
+#include "../tablemodel.h"
+
+RemoveRowsCommand::RemoveRowsCommand(TableModel* model,
+                                     const int startRow,
+                                     const int nRows,
+                                     QUndoCommand* parent)
+    : QUndoCommand(parent)
+    , m_tableModel(model)
+    , m_startRow(startRow) {
+  qInfo() << "New RemoveCommand...";
+  const QString commandText =
+      QString("removing %1 item(s) on position %2").arg(nRows).arg(startRow);
+  setText(commandText);
+
+  for (int row = 0; row < nRows; ++row) {
+    const int rowPosition = startRow + row;
+    QModelIndex index     = m_tableModel->index(rowPosition, 0);
+
+    ModelItemValues values = m_tableModel->getItemValues(index);
+
+    m_valueList.append(values);
+  }
+}
+
+void RemoveRowsCommand::undo() {
+  qDebug() << "Undoing the RemoveCommand...";
+  if (m_tableModel) {
+    m_tableModel->execInsertItems(m_startRow, m_valueList);
+  }
+}
+
+void RemoveRowsCommand::redo() {
+  qDebug() << "(Re-)doing the RemoveCommand...";
+  if (m_tableModel) {
+    m_tableModel->execRemoveItems(m_startRow, m_valueList.length());
+  }
+}

model/commands/removerowscommand.h

@@ -0,0 +1,30 @@
+#ifndef REMOVEROWSCOMMAND_H
+#define REMOVEROWSCOMMAND_H
+
+#include <QUndoCommand>
+
+class TableModel;
+
+typedef QMap<int, QVariant> ModelItemValues;
+
+class RemoveRowsCommand : public QUndoCommand {
+ public:
+  // TODO don't use simple pointer to model
+  /// Using simple pointer to model because there was a crash when closing the application with an
+  /// unclean undo stack
+  RemoveRowsCommand(TableModel* model,
+                    const int startRow,
+                    const int nRows,
+                    QUndoCommand* parent = nullptr);
+
+  /// QUndoCommand interface
+  void undo() override;
+  void redo() override;
+
+ private:
+  TableModel* m_tableModel;
+  const int m_startRow;
+  QList<ModelItemValues> m_valueList;
+};
+
+#endif  // REMOVEROWSCOMMAND_H

model/generalsortfiltermodel.cpp

@@ -0,0 +1,111 @@
+#include "generalsortfiltermodel.h"
+#include "metadata.h"
+
+#include <QItemSelection>
+
+GeneralSortFilterModel::GeneralSortFilterModel(std::shared_ptr<TableModel> sourceModel)
+    : QSortFilterProxyModel{sourceModel.get()}
+    , m_tableModel(sourceModel) {
+  setSourceModel(sourceModel.get());
+
+  m_collator.setNumericMode(true);
+}
+
+QItemSelection GeneralSortFilterModel::findItems(const QString& text) const {
+  QItemSelection result;
+
+  for (int i = 0; i < rowCount(); ++i) {
+    const QModelIndex localIndex = index(i, 0);
+    if (indexContainsText(localIndex, text)) {
+      result.select(localIndex, index(i, columnCount() - 1));  /// select entire row
+    }
+  }
+  return result;
+}
+
+QString GeneralSortFilterModel::getUuid(const QModelIndex& itemIndex) const {
+  return data(itemIndex, IdRole).toString();
+}
+
+QByteArray GeneralSortFilterModel::jsonDataForServer(const QModelIndex& proxyIndex) {
+  const QModelIndex sourceIndex = mapToSource(proxyIndex);
+  return m_tableModel->jsonDataForServer(sourceIndex);
+}
+
+void GeneralSortFilterModel::appendItems(const QByteArray& jsonDoc) {
+  m_tableModel->appendItems(jsonDoc);
+}
+
+bool GeneralSortFilterModel::removeRows(int firstRow, int nRows, const QModelIndex& parentIndex) {
+  const QModelIndex proxyIndex  = index(firstRow, 0, parentIndex);
+  const QModelIndex sourceIndex = mapToSource(proxyIndex);
+  return m_tableModel->removeRows(sourceIndex.row(), nRows, sourceIndex.parent());
+}
+
+bool GeneralSortFilterModel::lessThan(const QModelIndex& source_left,
+                                      const QModelIndex& source_right) const {
+  if (source_left.column() != source_right.column()) {
+    return false;
+  }
+
+  QAbstractItemModel* localSourceModel = sourceModel();
+  const int role                       = GET_ROLE_FOR_COLUMN(source_left.column());
+  const QVariant leftData              = localSourceModel->data(source_left);
+  const QVariant rightData             = localSourceModel->data(source_right);
+
+  const bool isText = STRING_ROLES.contains(role);
+  if (isText) {
+    const QString leftString  = leftData.toString();
+    const QString rightString = rightData.toString();
+    return m_collator.compare(leftString, rightString) > 0;
+  }
+  const bool isType = TYPE_ROLES.contains(role);
+  if (isType) {
+    const QString leftString  = leftData.toString();
+    const QString rightString = rightData.toString();
+    return m_collator.compare(leftString, rightString) > 0;
+  }
+  const bool isInt = INT_ROLES.contains(role);
+  if (isInt) {
+    const int leftInt  = leftData.toInt();
+    const int rightInt = rightData.toInt();
+    return leftInt > rightInt;
+  }
+  const bool isDouble = DOUBLE_ROLES.contains(role);
+  if (isDouble) {
+    const int leftInt  = leftData.toDouble();
+    const int rightInt = rightData.toDouble();
+    return leftInt > rightInt;
+  }
+  return false;
+}
+
+bool GeneralSortFilterModel::indexContainsText(const QModelIndex& index,
+                                               const QString& text) const {
+  // iterate over USER_FACING_ROLES and call roleDataContainsText(...);
+  // ...for each until text is found or no more roles to check;
+  QListIterator<UserRoles> i(USER_FACING_ROLES);
+  while (i.hasNext()) {
+    const UserRoles role   = i.next();
+    const bool isTextFound = roleDataContainsText(index, role, text);
+    if (isTextFound) {
+      // qInfo() << "Text is found in role:" << role;
+      return true;
+      // } else {
+      //   qDebug() << QString("Can't find text in role %1. Continuing search...").arg(role);
+    }
+  }
+  // qWarning() << "Text not found in any role. Returning false...";
+  return false;
+}
+
+bool GeneralSortFilterModel::roleDataContainsText(const QModelIndex& index,
+                                                  const int role,
+                                                  const QString& text) const {
+  const QString dataString = index.data(role).toString();
+  if (dataString.contains(text, Qt::CaseInsensitive)) {
+    return true;
+  } else {
+    return false;
+  }
+}

model/generalsortfiltermodel.h

@@ -0,0 +1,39 @@
+#ifndef GENERALSORTFILTERMODEL_H
+#define GENERALSORTFILTERMODEL_H
+
+#include <QCollator>
+#include <QSortFilterProxyModel>
+
+#include "tablemodel.h"
+
+class GeneralSortFilterModel : public QSortFilterProxyModel {
+  Q_OBJECT
+ public:
+  explicit GeneralSortFilterModel(std::shared_ptr<TableModel> sourceModel = nullptr);
+
+  /** Returns a QItemSelection with all ModelIndexes which contain the given text.
+   * @brief Returns QItemSelection containing all successful ModelIndex results
+   * @param text To search for
+   * @return QItemSelection containing all successful ModelIndex results
+   */
+  QItemSelection findItems(const QString& text) const;
+  QString getUuid(const QModelIndex& itemIndex) const;
+
+  QByteArray jsonDataForServer(const QModelIndex& proxyIndex);
+
+ public slots:
+  void appendItems(const QByteArray& jsonDoc);
+  bool removeRows(int firstRow, int nRows, const QModelIndex& parentIndex = QModelIndex()) override;
+  /// QSortFilterProxyModel interface
+ protected:
+  bool lessThan(const QModelIndex& sourceLeft, const QModelIndex& sourceRight) const override;
+
+ private:
+  std::shared_ptr<TableModel> m_tableModel;
+  QCollator m_collator;  /// for sorting
+
+  bool indexContainsText(const QModelIndex& index, const QString& text) const;
+  bool roleDataContainsText(const QModelIndex& index, const int role, const QString& text) const;
+};
+
+#endif  // GENERALSORTFILTERMODEL_H

model/metadata.h

@@ -0,0 +1,96 @@
+#ifndef METADATA_H
+#define METADATA_H
+
+#include <QDebug>
+#include <QHash>
+#include <QList>
+#include <QString>
+
+// TODO add namespace
+
+/// model data
+enum UserRoles {
+  NameRole = Qt::UserRole + 1,
+  DescriptionRole,
+  InfoRole,
+  TypeRole,
+  AmountRole,
+  FactorRole,
+  /// Non user facing
+  IdRole,
+  /// read only roles
+  ToStringRole,
+  ToJsonRole
+};
+
+static UserRoles DEFAULT_ROLE = NameRole;
+// TODO ?rename USER_FACING_ROLES -> MAIN_ROLES ?
+static QList<UserRoles> USER_FACING_ROLES = {NameRole, DescriptionRole, InfoRole,
+                                             TypeRole, AmountRole,      FactorRole};
+static QHash<int, QByteArray> ROLE_NAMES  = {
+    {NameRole, "name"},           {DescriptionRole, "description"},
+    {InfoRole, "info"},           {TypeRole, "type"},
+    {AmountRole, "amount"},       {FactorRole, "factor"},
+    {ToStringRole, "ToString"},   {IdRole, "id"},
+    {Qt::DisplayRole, "display"}, {Qt::EditRole, "edit"}};
+
+static QList<UserRoles> STRING_ROLES = {NameRole, DescriptionRole, InfoRole, IdRole};
+static QList<UserRoles> INT_ROLES    = {AmountRole};
+static QList<UserRoles> DOUBLE_ROLES = {FactorRole};
+
+static const QList<UserRoles> TYPE_ROLES = {TypeRole};
+static const QList<QString> TYPES        = {"A", "B", "C", ""};
+
+/// JSON keys
+static const QString ITEMS_KEY_STRING = "items";
+static const QString ITEM_KEY_STRING  = "item";
+
+/// file naming
+static const QString ITEMS_FILE_NAME = ITEMS_KEY_STRING + ".json";
+
+/// functions
+static UserRoles GET_ROLE_FOR_COLUMN(const int column) {
+  switch (column) {
+    case 0:
+      return NameRole;
+      break;
+    case 1:
+      return DescriptionRole;
+      break;
+    case 2:
+      return InfoRole;
+      break;
+    case 3:
+      return TypeRole;
+      break;
+    case 4:
+      return AmountRole;
+      break;
+    case 5:
+      return FactorRole;
+      break;
+    default:
+      qWarning() << QString("No role found for column %1! Returning 'NameRole'...").arg(column);
+      return NameRole;
+      break;
+  }
+}
+
+static int GET_COLUMN_FOR_ROLE(const UserRoles role) { return USER_FACING_ROLES.indexOf(role); }
+
+static QList<QString> GET_HEADER_NAMES() {
+  QList<QString> result;
+  for (const UserRoles& role : USER_FACING_ROLES) {
+    const QString headerName = ROLE_NAMES.value(role);
+    result.append(headerName);
+  }
+  return result;
+}
+
+static QString GET_HEADER_FOR_COLUMN(const int column) {
+  const UserRoles role     = GET_ROLE_FOR_COLUMN(column);
+  const QString headerName = ROLE_NAMES.value(role);
+  return headerName;
+}
+
+#endif  // METADATA_H

model/modelitem.cpp

@@ -0,0 +1,72 @@
+#include "modelitem.h"
+
+#include <QJsonObject>
+#include <QJsonValue>
+
+#include "../formats/jsonparser.h"
+#include "metadata.h"
+
+ModelItem::ModelItem(const ModelItemValues values)
+    : m_values(values) {}
+
+QVariant ModelItem::data(int role) const { return m_values.value(role); }
+
+bool ModelItem::setData(const QVariant& value, int role) {
+  bool valueChanged = false;
+  if (m_values.contains(role)) {
+    if (m_values.value(role) != value) {
+      valueChanged = true;
+    }
+  }
+  m_values[role] = value;
+
+  return valueChanged;
+}
+
+bool ModelItem::setItemData(const QMap<int, QVariant>& changedValues) {
+  bool valueChanged = false;
+
+  QMap<int, QVariant>::const_iterator citer = changedValues.constBegin();
+
+  while (citer != changedValues.constEnd()) {
+    const int role       = citer.key();
+    const QVariant value = citer.value();
+
+    if (m_values.contains(role)) {
+      if (m_values.value(role) != value) {
+        valueChanged = true;
+      }
+    }
+    m_values[role] = value;
+
+    citer++;
+  }
+
+  return valueChanged;
+}
+
+QString ModelItem::toString() const {
+  QString result;
+
+  QListIterator<UserRoles> i(USER_FACING_ROLES);
+  while (i.hasNext()) {
+    const UserRoles role   = i.next();
+    const QString roleName = ROLE_NAMES.value(role);
+    const QVariant value   = data(role);
+    // result.append(value.toString());
+    result.append(QString("%1: %2\n").arg(roleName, data(role).toString()));
+  }
+
+  const UserRoles idRole = IdRole;
+  QVariant idValue       = data(idRole);
+  if (!idValue.isNull()) {
+    const QString idRoleName = ROLE_NAMES.value(idRole);
+    result.append(QString("%1: %2\n").arg(idRoleName, idValue.toString()));
+  }
+  return result;
+}
+
+QJsonObject ModelItem::toJsonObject() const {
+  QJsonObject itemObject = JsonParser::itemValuesToJsonObject(m_values);
+  return itemObject;
+}

model/modelitem.h

@@ -0,0 +1,24 @@
+#ifndef MODELITEM_H
+#define MODELITEM_H
+
+#include <QVariant>
+
+typedef QMap<int, QVariant> ModelItemValues;
+
+class ModelItem {
+ public:
+  ModelItem(const ModelItemValues values);
+
+  QVariant data(int role) const;
+  bool setData(const QVariant& value, int role);
+  // TODO change return value to list of changed roles
+  bool setItemData(const QMap<int, QVariant>& changedValues);
+
+  QString toString() const;
+  QJsonObject toJsonObject() const;
+
+ private:
+  ModelItemValues m_values;
+};
+
+#endif  // MODELITEM_H

model/tablemodel.cpp

@@ -0,0 +1,409 @@
+#include "tablemodel.h"
+
+#include "../formats/jsonparser.h"
+#include "commands/edititemcommand.h"
+#include "commands/insertrowscommand.h"
+#include "commands/removerowscommand.h"
+#include "metadata.h"
+#include "modelitem.h"
+
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QJsonObject>
+
+QByteArray TableModel::generateExampleItems() {
+  QJsonDocument doc = QJsonDocument();
+  QJsonObject rootObject;
+  QJsonArray array;
+
+  // TODO use JsonParser for the item generation
+  for (int row = 0; row < 5; ++row) {
+    QJsonObject itemObject;
+    //  itemObject.insert("uuid", m_uuid.toString());
+    //  itemObject.insert("entryDateUTC", m_entryDateUTC.toString(Qt::ISODate));
+    itemObject.insert(ROLE_NAMES.value(NameRole), QString("Item %1").arg(row));
+    itemObject.insert(ROLE_NAMES.value(DescriptionRole), QString("This is item %1").arg(row));
+    itemObject.insert(ROLE_NAMES.value(InfoRole), QString("Info of item %1").arg(row));
+    itemObject.insert(ROLE_NAMES.value(AmountRole), row);
+    itemObject.insert(ROLE_NAMES.value(FactorRole), row * 1.1);
+
+    array.append(itemObject);
+  }
+  rootObject.insert(ITEMS_KEY_STRING, array);
+
+  doc.setObject(rootObject);
+  return doc.toJson();
+}
+
+TableModel::TableModel(QUndoStack* undoStack, QObject* parent)
+    : QAbstractTableModel{parent}
+    , m_undoStack(undoStack) {}
+
+Qt::ItemFlags TableModel::flags(const QModelIndex& index) const {
+  if (!index.isValid()) {
+    return QAbstractTableModel::flags(index);
+  }
+  return Qt::ItemIsEditable | QAbstractTableModel::flags(index);
+}
+
+QHash<int, QByteArray> TableModel::roleNames() const { return ROLE_NAMES; }
+
+int TableModel::rowCount(const QModelIndex& parent) const {
+  if (parent.isValid()) {
+    return 0;  /// no children
+  }
+  return m_items.size();
+}
+
+int TableModel::columnCount(const QModelIndex& parent) const {
+  if (parent.isValid()) {
+    return 0;  /// no children
+  }
+  return USER_FACING_ROLES.size();
+}
+
+QVariant TableModel::data(const QModelIndex& index, int role) const {
+  const int row    = index.row();
+  const int column = index.column();
+
+  if (!index.isValid()) {
+    return QVariant();
+  }
+  if (row >= rowCount(QModelIndex()) || column >= columnCount(QModelIndex())) {
+    return QVariant();
+  }
+
+  int roleForColumn = GET_ROLE_FOR_COLUMN(column);
+  switch (role) {
+    case Qt::DisplayRole:
+    case Qt::EditRole:
+      return m_items.at(row)->data(roleForColumn);
+    case ToStringRole:
+      return m_items.at(row)->toString();
+    case ToJsonRole:
+      return m_items.at(row)->toJsonObject();
+    case IdRole:
+      return m_items.at(row)->data(role);
+    default:
+      return m_items.at(row)->data(role);
+  }
+  return QVariant();
+}
+
+QVariant TableModel::headerData(int section, Qt::Orientation orientation, int role) const {
+  if (role == Qt::DisplayRole) {
+    if (orientation == Qt::Horizontal) {
+      const int columnRole     = GET_ROLE_FOR_COLUMN(section);
+      const QString headerName = ROLE_NAMES.value(columnRole);
+      return QString("%1").arg(headerName);
+    } else {
+      return QString("%1").arg(section);
+    }
+  }
+  return QVariant();
+}
+
+bool TableModel::setData(const QModelIndex& index, const QVariant& value, int role) {
+  if (checkIndex(index)) {
+    const int adjustedRole = getAppropriateRoleForIndex(index, role);
+    return setItemData(index, {{adjustedRole, value}});
+  }
+  return false;
+}
+
+bool TableModel::setItemData(const QModelIndex& index, const QMap<int, QVariant>& roles) {
+  if (!checkIndex(index)) {
+    return false;
+  }
+  // if (isRoleReadOnly(roleForColumn)) {
+  //   return false;
+  // }
+
+  QMap<int, QVariant> changedValues = onlyChangedValues(index, roles);
+  if (changedValues.size() > 0) {
+    EditItemCommand* editCommand = new EditItemCommand(this, index, changedValues);
+    m_undoStack->push(editCommand);
+    return true;
+  }
+  return false;
+}
+
+ModelItemValues TableModel::getItemValues(const QModelIndex& index) const {
+  ModelItemValues values;
+
+  QListIterator<UserRoles> i(USER_FACING_ROLES);
+  while (i.hasNext()) {
+    const UserRoles role = i.next();
+    values.insert(role, data(index, role));
+  }
+  return values;
+}
+
+QJsonDocument TableModel::getAllItemsAsJsonDoc() const {
+  QJsonDocument doc = QJsonDocument();
+  QJsonObject rootObject;
+  QJsonArray array;
+
+  foreach (shared_ptr<ModelItem> item, m_items) {
+    QJsonObject itemObject = item->toJsonObject();
+    array.append(itemObject);
+  }
+  rootObject.insert(ITEMS_KEY_STRING, array);
+
+  doc.setObject(rootObject);
+  return doc;
+}
+
+QList<QStringList> TableModel::getItemsAsStringLists() const {
+  QList<QStringList> result;
+  foreach (shared_ptr<ModelItem> item, m_items) {
+    QStringList valueList;
+    for (int column = 0; column < columnCount(); ++column) {
+      QString value = item->data(GET_ROLE_FOR_COLUMN(column)).toString();
+      valueList.append(value);
+    }
+    result.append(valueList);
+  }
+  return result;
+}
+
+// TODO use item selection as parameter to wrap multiple items into JSON data structure
+QByteArray TableModel::jsonDataForServer(const QModelIndex& currentIndex) const {
+  const QJsonObject itemObject = data(currentIndex, ToJsonRole).toJsonObject();
+  QJsonObject rootObject;
+  rootObject.insert(ITEM_KEY_STRING, itemObject);
+  const QJsonDocument jsonDoc(rootObject);
+  return jsonDoc.toJson(QJsonDocument::Compact);
+}
+
+QString TableModel::updateItemsFromJson(const QByteArray& jsonData) {
+  const QList<ModelItemValues> valueList = JsonParser::toItemValuesList(jsonData, ITEM_KEY_STRING);
+  int nChangedItems                      = 0;
+  for (const ModelItemValues& itemValues : valueList) {
+    bool updateHappened = updateItem(itemValues);
+    if (updateHappened) {
+      nChangedItems++;
+    }
+  }
+  return QString("Found and updated %1 item(s).").arg(nChangedItems);
+}
+
+bool TableModel::updateItem(const ModelItemValues& itemValues) {
+  QModelIndex foundIndex = searchItemIndex(itemValues);
+
+  qDebug() << "Search done!";
+  if (foundIndex == QModelIndex()) {
+    const QString errorMessage = "No matching item found!";
+    qWarning() << errorMessage;
+    return false;
+  } else {
+    qInfo() << "Item found!";
+    /// update existing item
+    setItemData(foundIndex, itemValues);
+    return true;
+  }
+}
+
+bool TableModel::removeRows(int firstRow, int nRows, const QModelIndex& parentIndex) {
+  if (parentIndex != QModelIndex()) {
+    qWarning() << "Removing of child rows is not supported yet!";
+    return false;
+  }
+
+  const int lastRow = firstRow + nRows - 1;
+  if (firstRow < 0 || lastRow >= m_items.size()) {
+    qWarning() << "Trying to remove rows is out of bounds!";
+    return false;
+  }
+
+  RemoveRowsCommand* removeCommand = new RemoveRowsCommand(this, firstRow, nRows);
+  m_undoStack->push(removeCommand);
+
+  return true;
+}
+
+void TableModel::appendItems(const QByteArray& jsonDoc) { insertItems(-1, jsonDoc, QModelIndex()); }
+
+void TableModel::insertItems(int startPosition,
+                             const QByteArray& jsonDoc,
+                             const QModelIndex& parentIndex) {
+  const QList<ModelItemValues> valueList = JsonParser::toItemValuesList(jsonDoc, ITEMS_KEY_STRING);
+
+  if (valueList.empty()) {
+    /// don't try inserting if no values to insert
+    qDebug() << "No items found in JSON document. Not adding anything...";
+    return;
+  }
+
+  insertItems(startPosition, valueList, parentIndex);
+}
+
+void TableModel::insertItems(int startPosition,
+                             const QList<ModelItemValues>& itemValuesList,
+                             const QModelIndex& parentIndex) {
+  qInfo() << "Inserting item(s) into model...";
+  if (parentIndex != QModelIndex()) {
+    qWarning()
+        << "Using invalid parent index (no child support for now)! Using root index as parent...";
+  }
+  if (startPosition == -1 || startPosition > m_items.size()) {
+    /// Appending item(s)
+    startPosition = m_items.size();
+  }
+
+  InsertRowsCommand* insertCommand = new InsertRowsCommand(this, startPosition, itemValuesList);
+  m_undoStack->push(insertCommand);
+}
+
+void TableModel::execInsertItems(const int firstRow, const QList<ModelItemValues> valueList) {
+  const int nRows = valueList.size();
+  qDebug() << "Inserting" << nRows << "items...";
+
+  const int lastRow = firstRow + nRows - 1;
+  beginInsertRows(QModelIndex(), firstRow, lastRow);
+  for (int row = 0; row < nRows; ++row) {
+    const int rowPosition      = firstRow + row;
+    shared_ptr<ModelItem> item = make_unique<ModelItem>(valueList.at(row));
+    m_items.insert(rowPosition, std::move(item));
+  }
+  endInsertRows();
+}
+
+void TableModel::execRemoveItems(const int firstRow, const int nRows) {
+  const int lastRow = firstRow + nRows - 1;
+  beginRemoveRows(QModelIndex(), firstRow, lastRow);
+  m_items.remove(firstRow, nRows);
+  endRemoveRows();
+}
+
+void TableModel::execEditItemData(const int row, const QMap<int, QVariant>& changedValues) {
+  shared_ptr<ModelItem> item = m_items.at(row);
+  bool isDataChanged         = item->setItemData(changedValues);
+
+  if (isDataChanged) {
+    /// FIXME due to the mapping from roles to the DisplayRole of different columns the complete row
+    /// is getting notified about (potential) data changes; dataChanged should be called only for
+    /// the affected columns
+    const QModelIndex firstIndex = this->index(row, 0);
+    const QModelIndex lastIndex  = this->index(row, USER_FACING_ROLES.size() - 1);
+    QList<int> roles             = changedValues.keys();
+    roles.insert(0, Qt::DisplayRole);
+    emit dataChanged(firstIndex, lastIndex, roles.toVector());
+  }
+}
+
+QMap<int, QVariant> TableModel::onlyChangedValues(const QModelIndex& index,
+                                                  const QMap<int, QVariant>& roleValueMap) const {
+  QMap<int, QVariant> result;
+  QMap<int, QVariant>::const_iterator i;
+  for (i = roleValueMap.constBegin(); i != roleValueMap.constEnd(); ++i) {
+    const int role          = i.key();
+    const QVariant newValue = i.value();
+    const QVariant oldValue = index.data(role);
+    // TODO check if role is a editable role?
+    if (oldValue != newValue) {
+      bool emptyValueIsEqualToZero = isEmptyValueEqualToZero(role);
+      // REFACTOR the next if statement is too complex
+      if (emptyValueIsEqualToZero && oldValue == QVariant() && newValue == 0) {
+        qDebug() << "oldValue:" << oldValue << "& newValue:" << newValue
+                 << "mean the same. Ignoring...";
+        continue;
+      }
+      qDebug() << "oldValue:" << oldValue << "!= newValue:" << newValue;
+      result.insert(role, newValue);
+    } else {
+      qInfo() << "oldValue is already the same as newValue:" << oldValue << "-> ignoring...";
+    }
+  }
+  return result;
+}
+
+bool TableModel::isEmptyValueEqualToZero(const int role) const {
+  if (INT_ROLES.contains(role)) {
+    return true;
+  } else if (DOUBLE_ROLES.contains(role)) {
+    return true;
+  } else {
+    return false;
+  }
+}
+
+int TableModel::getAppropriateRoleForIndex(const QModelIndex& index, const int role) const {
+  /// cases:
+  /// 1. Qt::DisplayRole, Qt::EditRole
+  ///   -> get role for column
+  /// 2. other roles
+  ///   -> use role as given
+  const int column        = index.column();
+  const int roleForColumn = GET_ROLE_FOR_COLUMN(column);
+  switch (role) {
+    case Qt::DisplayRole:
+    case Qt::EditRole:
+      return roleForColumn;
+      break;
+    default:
+      return role;
+      break;
+  }
+}
+
+QModelIndex TableModel::searchItemIndex(const ModelItemValues givenItemValues) const {
+  // iterate over indexes to search item : see searchItem(...);
+  // for (const shared_ptr<ModelItem>& item : m_items) {
+  for (int row = 0; row < rowCount(); ++row) {
+    qDebug() << "Processing item at row" << row << "...";
+    QModelIndex itemIndex = index(row, 0);
+    if (isItemEqualToItemValues(itemIndex, givenItemValues)) {
+      qInfo() << "Found item at row" << row << "! Returning its index...";
+      return itemIndex;
+    }
+  }
+  qDebug() << "No matching item found. Returning empty pointer...";
+  return {};
+}
+
+bool TableModel::isItemEqualToItemValues(const QModelIndex& itemIndex,
+                                         const ModelItemValues givenItemValues) const {
+  /// do both have a UUID?
+  QVariant idOfItem = data(itemIndex, IdRole);
+  QVariant given    = givenItemValues.value(IdRole);
+  if (idOfItem.isValid() && given.isValid()) {
+    /// are the UUIDs the same?
+    if (idOfItem.toString() == given.toString()) {
+      qInfo() << "UUIDs are the same.";
+      return true;
+    } else {
+      qDebug() << "UUIDs are NOT the same.";
+      return false;
+    }
+  } else {
+    /// are all other values the same? (for now only USER_FACING_ROLES are checked)
+    QListIterator<UserRoles> i(USER_FACING_ROLES);
+    while (i.hasNext()) {
+      const UserRoles role       = i.next();
+      const QString roleName     = ROLE_NAMES.value(role);
+      const QVariant valueOfItem = data(itemIndex, role);
+      const QVariant givenValue  = givenItemValues.value(role);
+      if (STRING_ROLES.contains(role)) {
+        if (valueOfItem.toString() != givenValue.toString()) {
+          return false;
+        }
+      } else if (TYPE_ROLES.contains(role)) {
+        if (valueOfItem.toString() != givenValue.toString()) {
+          return false;
+        }
+      } else if (INT_ROLES.contains(role)) {
+        if (valueOfItem.toInt() != givenValue.toInt()) {
+          return false;
+        }
+      } else if (DOUBLE_ROLES.contains(role)) {
+        if (valueOfItem.toDouble() != givenValue.toDouble()) {
+          return false;
+        }
+      } else {
+        qCritical() << QString("Can't find data type for role %1!!!").arg(role);
+      }
+    }
+    return true;
+  }
+}

model/tablemodel.h

@@ -0,0 +1,80 @@
+#ifndef TABLEMODEL_H
+#define TABLEMODEL_H
+
+#include <QAbstractTableModel>
+
+class QUndoStack;
+class ModelItem;
+
+using namespace std;
+
+typedef QMap<int, QVariant> ModelItemValues;
+
+class TableModel : public QAbstractTableModel {
+  Q_OBJECT
+
+  friend class InsertRowsCommand;
+  friend class RemoveRowsCommand;
+  friend class EditItemCommand;
+
+ public:
+  static QByteArray generateExampleItems();
+
+  explicit TableModel(QUndoStack* undoStack, QObject* parent = nullptr);
+
+  /// QAbstractItemModel interface
+  Qt::ItemFlags flags(const QModelIndex& index) const override;
+  QHash<int, QByteArray> roleNames() const override;
+
+  int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+  int columnCount(const QModelIndex& parent = QModelIndex()) const override;
+  QVariant data(const QModelIndex& index, int role) const override;
+  QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+
+  bool setData(const QModelIndex& index, const QVariant& value, int role) override;
+  bool setItemData(const QModelIndex& index, const QMap<int, QVariant>& roles) override;
+
+  ModelItemValues getItemValues(const QModelIndex& index) const;
+  QJsonDocument getAllItemsAsJsonDoc() const;
+  QList<QStringList> getItemsAsStringLists() const;
+
+  QByteArray jsonDataForServer(const QModelIndex& currentIndex) const;
+
+  QString updateItemsFromJson(const QByteArray& jsonData);
+  bool updateItem(const ModelItemValues& itemValues);
+
+ public slots:
+  // bool insertRows(int position, int rows, const QModelIndex& parentIndex = QModelIndex())
+  // override;
+  bool removeRows(int firstRow, int nRows, const QModelIndex& parentIndex = QModelIndex()) override;
+  void appendItems(const QByteArray& jsonDoc);
+  void insertItems(int startPosition,
+                   const QByteArray& jsonDoc,
+                   const QModelIndex& parentIndex = QModelIndex());
+  void insertItems(int startPosition,
+                   const QList<ModelItemValues>& itemValuesList,
+                   const QModelIndex& parentIndex = QModelIndex());
+
+ private:
+  /// *** members ***
+  // TODO shared_ptr -> unique_ptr
+  QList<shared_ptr<ModelItem>> m_items;
+  QUndoStack* m_undoStack;
+
+  /// *** functions ***
+  /// undo/redo functions
+  void execInsertItems(const int firstRow, const QList<ModelItemValues> valueList);
+  void execRemoveItems(const int firstRow, const int nRows);
+  void execEditItemData(const int row, const QMap<int, QVariant>& changedValues);
+
+  /// misc functions
+  QMap<int, QVariant> onlyChangedValues(const QModelIndex& index,
+                                        const QMap<int, QVariant>& roleValueMap) const;
+  bool isEmptyValueEqualToZero(const int role) const;
+  int getAppropriateRoleForIndex(const QModelIndex& index, const int role) const;
+  QModelIndex searchItemIndex(const ModelItemValues givenItemValues) const;
+  bool isItemEqualToItemValues(const QModelIndex& itemIndex,
+                               const ModelItemValues givenItemValues) const;
+};
+
+#endif  // TABLEMODEL_H

network/apiroutes.h

@@ -0,0 +1,12 @@
+#ifndef APIROUTES_H
+#define APIROUTES_H
+
+#include <QString>
+
+// TODO add namespace
+
+static const QString apiPrefix = "/api/";
+
+static const QString ROUTE_ITEMS = apiPrefix + "items";
+
+#endif  // APIROUTES_H

network/servercommunicator.cpp

@@ -0,0 +1,106 @@
+#include "servercommunicator.h"
+#include "apiroutes.h"
+
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QRestReply>
+
+using namespace Qt::StringLiterals;
+
+ServerCommunicator::ServerCommunicator(QObject* parent)
+    : QObject{parent} {
+  m_netManager.setAutoDeleteReplies(true);
+  m_restManager = std::make_shared<QRestAccessManager>(&m_netManager);
+  m_serviceApi  = std::make_shared<QNetworkRequestFactory>();
+}
+
+bool ServerCommunicator::sslSupported() {
+#if QT_CONFIG(ssl)
+  return QSslSocket::supportsSsl();
+#else
+  return false;
+#endif
+}
+
+QUrl ServerCommunicator::url() const { return m_serviceApi->baseUrl(); }
+
+void ServerCommunicator::setUrl(const QUrl& url) {
+  if (m_serviceApi->baseUrl() == url) {
+    return;
+  }
+  m_serviceApi->setBaseUrl(url);
+  QHttpHeaders authenticationHeaders;
+  authenticationHeaders.append(QHttpHeaders::WellKnownHeader::ContentType, "application/json");
+  m_serviceApi->setCommonHeaders(authenticationHeaders);
+  emit urlChanged();
+}
+
+void ServerCommunicator::fetchItems() {
+  /// Set up a GET request
+  m_restManager->get(m_serviceApi->createRequest(ROUTE_ITEMS), this, [this](QRestReply& reply) {
+    if (reply.isSuccess()) {
+      qInfo() << "Fetching items successful.";
+      const QJsonDocument doc = reply.readJson().value();
+      emit itemsFetched(doc.toJson());
+
+    } else {
+      if (reply.hasError()) {
+        const QString errorString = reply.errorString();
+        qCritical() << "ERROR:" << errorString;
+        emit itemsFetchFailure(errorString);
+      } else {
+        int statusCode = reply.httpStatus();
+        qCritical() << "ERROR:" << statusCode;
+        emit itemsFetchFailure(QString::number(statusCode));
+        emit itemsFetchFailure(QString("HTTP status code: %1").arg(statusCode));
+      }
+    }
+  });
+}
+
+void ServerCommunicator::postItems(const QByteArray& jsonData) {
+  QNetworkReply* reply = m_restManager->post(m_serviceApi->createRequest(ROUTE_ITEMS), jsonData);
+
+  QObject::connect(reply, &QNetworkReply::finished, [=]() {
+    if (reply->error() == QNetworkReply::NoError) {
+      QByteArray responseData = reply->readAll();
+      const QString message   = QString("POST successful! Response: %1").arg(responseData);
+      qInfo() << message;
+      emit postRequestSuccessful(responseData);
+    } else {
+      const QString message = QString("Error: %1").arg(reply->errorString());
+      qDebug() << message;
+      emit postRequestFailure(message);
+    }
+    reply->deleteLater();
+  });
+}
+
+void ServerCommunicator::deleteItem(const QString& id) {
+  const QString deleteRoute = QString("%1/%2").arg(ROUTE_ITEMS, id);
+  QNetworkReply* reply = m_restManager->deleteResource(m_serviceApi->createRequest(deleteRoute));
+
+  QObject::connect(reply, &QNetworkReply::finished, [=]() {
+    if (reply->error() == QNetworkReply::NoError) {
+      QByteArray responseData = reply->readAll();
+      const QString message   = QString("DELETE successful! Response: %1").arg(responseData);
+      qInfo() << message;
+      emit deleteRequestSuccessful(responseData);
+    } else {
+      const QString message = QString("Error: %1").arg(reply->errorString());
+      qDebug() << message;
+      emit deleteRequestFailure(message);
+    }
+    reply->deleteLater();
+  });
+}
+
+void ServerCommunicator::setServerConfiguration(const QString url,
+                                                const QString email,
+                                                const QString password) {
+  setUrl(url);
+
+  m_email    = email;
+  m_password = password;
+}

network/servercommunicator.h

@@ -0,0 +1,46 @@
+#ifndef SERVERCOMMUNICATOR_H
+#define SERVERCOMMUNICATOR_H
+
+#include <QNetworkAccessManager>
+#include <QNetworkRequestFactory>
+#include <QObject>
+#include <QRestAccessManager>
+
+class ServerCommunicator : public QObject {
+  Q_OBJECT
+ public:
+  explicit ServerCommunicator(QObject* parent = nullptr);
+
+  bool sslSupported();
+
+  QUrl url() const;
+  void setUrl(const QUrl& url);
+
+  void setServerConfiguration(const QString url, const QString email, const QString password);
+
+ public slots:
+  void fetchItems();
+  void postItems(const QByteArray& jsonData);
+  void deleteItem(const QString& id);
+
+ signals:
+  void urlChanged();
+
+  void itemsFetched(const QByteArray jsonDoc);
+  void itemsFetchFailure(const QString errorString);
+  void postRequestSuccessful(const QByteArray responseData);
+  void postRequestFailure(const QString errorString);
+  void deleteRequestSuccessful(const QByteArray responseData);
+  void deleteRequestFailure(const QString errorString);
+
+ private:
+  QNetworkAccessManager m_netManager;
+  std::shared_ptr<QRestAccessManager> m_restManager;
+  std::shared_ptr<QNetworkRequestFactory> m_serviceApi;
+
+  QString m_email;
+  QString m_password;
+  // QString m_authToken;
+};
+
+#endif  // SERVERCOMMUNICATOR_H

utils/messagehandler.h

@@ -0,0 +1,164 @@
+#ifndef MESSAGEHANDLER_H
+#define MESSAGEHANDLER_H
+/**
+ * Color and formatting codes
+ * @see: http://misc.flogisoft.com/bash/tip_colors_and_formatting
+ */
+
+#include <QObject>
+
+//  qSetMessagePattern("%{file}(%{line}): %{message}");
+//  qSetMessagePattern("%{type}(%{line}):\t%{message}");
+//  qSetMessagePattern("%{type}%{file}(%{line}):\t%{message}");
+
+void consoleHandlerColoredVerbose(QtMsgType type,
+                                  const QMessageLogContext& context,
+                                  const QString& msg) {
+  QByteArray localMsg = msg.toLocal8Bit();
+  switch (type) {
+    case QtDebugMsg:
+      //      fprintf(stderr, "\033[1;30mDebug: (%s:%u, %s) \t%s\n\033[0m", context.file,
+      //      context.line, context.function, localMsg.constData());  // bold
+      fprintf(stderr, "\033[107;30mDebug: (%s:%u, %s) \t%s\n\033[0m", context.file, context.line,
+              context.function, localMsg.constData());
+      break;
+    case QtInfoMsg:
+      fprintf(stderr, "\033[107;32mInfo:  (%s:%u) \t%s\n\033[0m", context.file, context.line,
+              localMsg.constData());
+      break;
+    case QtWarningMsg:
+      fprintf(stderr, "\033[43;30mWarning: (%s:%u, %s) \t%s\n\033[0m", context.file, context.line,
+              context.function, localMsg.constData());
+      break;
+    case QtCriticalMsg:
+      fprintf(stderr, "\033[41;30mCritical: (%s:%u, %s) \t%s\n\033[0m", context.file, context.line,
+              context.function, localMsg.constData());
+      break;
+    case QtFatalMsg:
+      fprintf(stderr, "\033[41;30mFatal: (%s:%u, %s) \t%s\n\033[0m", context.file, context.line,
+              context.function, localMsg.constData());
+      abort();
+  }
+}
+
+void consoleHandlerColoredVerboseInDarkTheme(QtMsgType type,
+                                             const QMessageLogContext& context,
+                                             const QString& msg) {
+  QByteArray localMsg = msg.toLocal8Bit();
+  switch (type) {
+    case QtDebugMsg:
+      //      fprintf(stderr, "\033[1;30mDebug: (%s:%u, %s) \t%s\n\033[0m", context.file,
+      //      context.line, context.function, localMsg.constData());  // bold
+      fprintf(stderr, "\033[107;37mDebug: (%s:%u, %s) \t%s\n\033[0m", context.file, context.line,
+              context.function, localMsg.constData());
+      break;
+    case QtInfoMsg:
+      fprintf(stderr, "\033[107;32mInfo:  (%s:%u) \t%s\n\033[0m", context.file, context.line,
+              localMsg.constData());
+      break;
+    case QtWarningMsg:
+      fprintf(stderr, "\033[43;30mWarning: (%s:%u, %s) \t%s\n\033[0m", context.file, context.line,
+              context.function, localMsg.constData());
+      break;
+    case QtCriticalMsg:
+      fprintf(stderr, "\033[41;30mCritical: (%s:%u, %s) \t%s\n\033[0m", context.file, context.line,
+              context.function, localMsg.constData());
+      break;
+    case QtFatalMsg:
+      fprintf(stderr, "\033[41;30mFatal: (%s:%u, %s) \t%s\n\033[0m", context.file, context.line,
+              context.function, localMsg.constData());
+      abort();
+  }
+}
+
+void consoleHandlerColored(QtMsgType type, const QMessageLogContext& context, const QString& msg) {
+  QByteArray localMsg = msg.toLocal8Bit();
+  switch (type) {
+    case QtDebugMsg:
+      fprintf(stderr, "\033[1;30mDebug: (%s:%u) \t%s\n\033[0m", context.file, context.line,
+              localMsg.constData());
+      break;
+    case QtInfoMsg:
+      fprintf(stderr, "\033[0;30mInfo:  (%s:%u) \t%s\n\033[0m", context.file, context.line,
+              localMsg.constData());
+      break;
+    case QtWarningMsg:
+      fprintf(stderr, "\033[1;33mWarning: (%s:%u) \t%s\n\033[0m", context.file, context.line,
+              localMsg.constData());
+      break;
+    case QtCriticalMsg:
+      fprintf(stderr, "\033[31mCritical: (%s:%u) \t%s\n\033[0m", context.file, context.line,
+              localMsg.constData());
+      break;
+    case QtFatalMsg:
+      fprintf(stderr, "\033[31mFatal: (%s:%u) \t%s\n\033[0m", context.file, context.line,
+              localMsg.constData());
+      abort();
+  }
+}
+
+void myMessageOutput(QtMsgType type, const QMessageLogContext& context, const QString& msg) {
+  QByteArray localMsg = msg.toLocal8Bit();
+  switch (type) {
+    case QtDebugMsg:
+      fprintf(stderr, "Debug: %s (%s:%u, %s)\n", localMsg.constData(), context.file, context.line,
+              context.function);
+      break;
+    case QtInfoMsg:
+      fprintf(stderr, "Info: %s (%s:%u, %s)\n", localMsg.constData(), context.file, context.line,
+              context.function);
+      break;
+    case QtWarningMsg:
+      fprintf(stderr, "Warning: %s (%s:%u, %s)\n", localMsg.constData(), context.file, context.line,
+              context.function);
+      break;
+    case QtCriticalMsg:
+      fprintf(stderr, "Critical: %s (%s:%u, %s)\n", localMsg.constData(), context.file,
+              context.line, context.function);
+      break;
+    case QtFatalMsg:
+      fprintf(stderr, "Fatal: %s (%s:%u, %s)\n", localMsg.constData(), context.file, context.line,
+              context.function);
+      abort();
+  }
+}
+
+#ifdef Q_OS_ANDROID
+#include <android/log.h>
+
+const char* const applicationName = "Pensieve";
+void androidMessageHandler(QtMsgType type, const QMessageLogContext& context, const QString& msg) {
+  QString report = msg;
+  if (context.file && !QString(context.file).isEmpty()) {
+    report += " in file ";
+    report += QString(context.file);
+    report += " line ";
+    report += QString::number(context.line);
+  }
+  if (context.function && !QString(context.function).isEmpty()) {
+    report += +" function ";
+    report += QString(context.function);
+  }
+  const char* const local = report.toLocal8Bit().constData();
+  switch (type) {
+    case QtDebugMsg:
+      __android_log_write(ANDROID_LOG_DEBUG, applicationName, local);
+      break;
+    case QtInfoMsg:
+      __android_log_write(ANDROID_LOG_INFO, applicationName, local);
+      break;
+    case QtWarningMsg:
+      __android_log_write(ANDROID_LOG_WARN, applicationName, local);
+      break;
+    case QtCriticalMsg:
+      __android_log_write(ANDROID_LOG_ERROR, applicationName, local);
+      break;
+    case QtFatalMsg:
+    default:
+      __android_log_write(ANDROID_LOG_FATAL, applicationName, local);
+      abort();
+  }
+}
+#endif
+
+#endif  // MESSAGEHANDLER_H