Merge branch 'feature/restClient' into develop

CMakeLists.txt

@@ -12,6 +12,7 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 find_package(QT NAMES Qt6 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)
 
 configure_file(CoreConfig.h.in CoreConfig.h)
 
@@ -32,16 +33,18 @@ add_library(${TARGET_APP} STATIC
   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
-  model/generalsortfiltermodel.h model/generalsortfiltermodel.cpp
 )
 
-
-target_link_libraries(GenericCore PRIVATE Qt${QT_VERSION_MAJOR}::Test)
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
 
 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)
 

data/filehandler.h

@@ -3,7 +3,7 @@
 
 #include <QVariant>
 
-typedef QHash<int, QVariant> ModelItemValues;
+typedef QMap<int, QVariant> ModelItemValues;
 
 class QJsonDocument;
 class QString;

formats/csvparser.cpp

@@ -86,7 +86,7 @@ QHash<QString, std::vector<std::string>> CsvParser::extractColumnValues(
     const rapidcsv::Document& doc) {
   QHash<QString, std::vector<std::string>> columnValueMap;
   for (const QString& columnName : headerNames) {
-    // NEXT add support for optional columns
+    // TODO add support for optional columns
     // if (optionalCsvHeaderNames.contains(columnName)) {
     //   const std::vector<std::string> columnNames = doc.GetColumnNames();
     //   int columnIdx                              = doc.GetColumnIdx(columnName.toStdString());
@@ -147,7 +147,7 @@ QVariant CsvParser::parseItemValue(const int role, const std::string& valueStrin
     result = doubleValue;
 
     // } else if (typeColumns.contains(columnName)) {
-    //   // NEXT validate string is allowed
+    //   // TODO validate string is allowed
     //   values[role] = QString::fromStdString(columnValueMap.value(columnName).at(row));
   } else {
     /// no type recognized for column

formats/csvparser.h

@@ -3,7 +3,7 @@
 
 #include <QString>
 
-typedef QHash<int, QVariant> ModelItemValues;
+typedef QMap<int, QVariant> ModelItemValues;
 
 namespace rapidcsv {
 class Document;

formats/jsonparser.cpp

@@ -6,20 +6,34 @@
 #include "../model/metadata.h"
 
 QList<ModelItemValues> JsonParser::toItemValuesList(const QByteArray& jsonData,
-                                                    const QString& objectName) {
+                                                    const QString& rootValueName) {
   QList<ModelItemValues> result;
 
   if (jsonData.isEmpty()) {
     return result;
   }
+  // TODO tidy up the following code and encapsulate into functions;
 
-  QJsonArray itemArray = extractItemArray(jsonData, objectName);
+  QJsonDocument doc = QJsonDocument::fromJson(jsonData);
 
-  foreach (QJsonValue value, itemArray) {
-    QJsonObject itemJsonObject = value.toObject();
+  /// 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;
 }
 
@@ -28,7 +42,7 @@ QByteArray JsonParser::itemValuesListToJson(const QList<ModelItemValues>& itemVa
   QJsonDocument jsonDoc;
   QJsonObject rootObject;
   QJsonArray itemArray;
-  for (const QHash<int, QVariant>& itemValues : itemValuesList) {
+  for (const ModelItemValues& itemValues : itemValuesList) {
     QJsonObject itemObject;
 
     QListIterator<UserRoles> i(USER_FACING_ROLES);
@@ -58,23 +72,28 @@ QByteArray JsonParser::itemValuesListToJson(const QList<ModelItemValues>& itemVa
 
 JsonParser::JsonParser() {}
 
-QJsonArray JsonParser::extractItemArray(const QByteArray& jsonData, const QString& objectName) {
-  QJsonDocument doc = QJsonDocument::fromJson(jsonData);
+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();

formats/jsonparser.h

@@ -8,21 +8,21 @@ class QString;
 class QByteArray;
 class QJsonArray;
 
-typedef QHash<int, QVariant> ModelItemValues;
+typedef QMap<int, QVariant> ModelItemValues;
 
 using namespace std;
 
 class JsonParser {
  public:
   static QList<ModelItemValues> toItemValuesList(const QByteArray& jsonData,
-                                                 const QString& objectName = "");
+                                                 const QString& rootValueName = "");
   static QByteArray itemValuesListToJson(const QList<ModelItemValues>& itemValuesList,
                                          const QString& objectName = "");
 
  private:
   explicit JsonParser();
 
-  static QJsonArray extractItemArray(const QByteArray& jsonData, const QString& objectName);
+  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);

genericcore.cpp

@@ -13,9 +13,11 @@
 #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>
 
@@ -37,6 +39,7 @@ GenericCore::GenericCore() {
   m_modelUndoStack = new QUndoStack(this);
 
   setupModels();
+  setupServerConfiguration();
 }
 
 GenericCore::~GenericCore() { qDebug() << "Destroying core..."; }
@@ -103,7 +106,7 @@ void GenericCore::saveItems() {
   qDebug() << "saving items...";
 
   const QJsonDocument doc   = m_mainModel->getAllItemsAsJsonDoc();
-  const bool successfulSave = FileHandler::saveToFile(doc, ITEM_FILE_NAME);
+  const bool successfulSave = FileHandler::saveToFile(doc, ITEMS_FILE_NAME);
   if (successfulSave) {
     m_modelUndoStack->setClean();
     emit displayStatusMessage(QString("Items saved."));
@@ -116,7 +119,7 @@ void GenericCore::importCSVFile(const QString& filePath) {
   qInfo() << "importing items from CSV...";
   qDebug() << "filePath:" << filePath;
   const QList<ModelItemValues> itemValuesList = FileHandler::getItemValuesFromCSVFile(filePath);
-  // NEXT inform UI on errors
+  // TODO inform UI on errors
   if (itemValuesList.isEmpty()) {
     qDebug() << "No items found. Doing nothing...";
     return;
@@ -132,6 +135,58 @@ bool GenericCore::exportCSVFile(const QString& filePath) {
   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);
@@ -159,7 +214,7 @@ void GenericCore::setupModels() {
  */
 void GenericCore::initModelData() {
   qInfo() << "Trying to read model data from file...";
-  const QByteArray jsonDoc = FileHandler::loadJSONDataFromFile(ITEM_FILE_NAME);
+  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)
@@ -188,3 +243,39 @@ QString GenericCore::getMaintenanceToolFilePath() const {
   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

@@ -10,6 +10,7 @@ class QString;
 
 class TableModel;
 class GeneralSortFilterModel;
+class ServerCommunicator;
 
 class GenericCore : public QObject {
   Q_OBJECT
@@ -32,8 +33,24 @@ class GenericCore : public QObject {
   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;
@@ -46,6 +63,11 @@ class GenericCore : public QObject {
   void initModelData();
 
   QString getMaintenanceToolFilePath() const;
+
+  /// Network communication
+  std::unique_ptr<ServerCommunicator> m_serverCommunicator;
+  void setupServerConfiguration();
+  void applyServerConfiguration();
 };
 
 #endif  // GENERICCORE_H

model/commands/edititemcommand.cpp

@@ -26,6 +26,11 @@ EditItemCommand::EditItemCommand(TableModel* model,
                         .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());

model/commands/insertrowscommand.h

@@ -3,7 +3,7 @@
 
 #include <QUndoCommand>
 
-typedef QHash<int, QVariant> ModelItemValues;
+typedef QMap<int, QVariant> ModelItemValues;
 
 class TableModel;
 

model/commands/removerowscommand.h

@@ -5,7 +5,7 @@
 
 class TableModel;
 
-typedef QHash<int, QVariant> ModelItemValues;
+typedef QMap<int, QVariant> ModelItemValues;
 
 class RemoveRowsCommand : public QUndoCommand {
  public:

model/generalsortfiltermodel.cpp

@@ -23,6 +23,15 @@ QItemSelection GeneralSortFilterModel::findItems(const QString& text) const {
   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);
 }

model/generalsortfiltermodel.h

@@ -17,6 +17,9 @@ class GeneralSortFilterModel : public QSortFilterProxyModel {
    * @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);

model/metadata.h

@@ -6,6 +6,8 @@
 #include <QList>
 #include <QString>
 
+// TODO add namespace
+
 /// model data
 enum UserRoles {
   NameRole = Qt::UserRole + 1,
@@ -13,26 +15,31 @@ enum UserRoles {
   InfoRole,
   AmountRole,
   FactorRole,
-  /// helper roles
-  ToStringRole
+  /// Non user facing
+  IdRole,
+  /// read only roles
+  ToStringRole,
+  ToJsonRole
 };
-static UserRoles DEFAULT_ROLE             = NameRole;
+
+static UserRoles DEFAULT_ROLE = NameRole;
+// TODO ?rename USER_FACING_ROLES -> MAIN_ROLES ?
 static QList<UserRoles> USER_FACING_ROLES = {NameRole, DescriptionRole, InfoRole, AmountRole,
                                              FactorRole};
-static QHash<int, QByteArray> ROLE_NAMES  = {{NameRole, "Name"},
-                                             {DescriptionRole, "Description"},
-                                             {InfoRole, "Info"},
-                                             {AmountRole, "Amount"},
-                                             {FactorRole, "Factor"}};
-static QList<UserRoles> STRING_ROLES      = {NameRole, DescriptionRole, InfoRole};
-static QList<UserRoles> INT_ROLES         = {AmountRole};
-static QList<UserRoles> DOUBLE_ROLES      = {FactorRole};
+static QHash<int, QByteArray> ROLE_NAMES  = {
+    {NameRole, "name"},     {DescriptionRole, "description"}, {InfoRole, "info"},
+    {AmountRole, "amount"}, {FactorRole, "factor"},           {ToStringRole, "ToString"},
+    {IdRole, "id"}};
+static QList<UserRoles> STRING_ROLES = {NameRole, DescriptionRole, InfoRole, IdRole};
+static QList<UserRoles> INT_ROLES    = {AmountRole};
+static QList<UserRoles> DOUBLE_ROLES = {FactorRole};
 
 /// JSON keys
-static const QString ITEM_KEY_STRING = "items";
+static const QString ITEMS_KEY_STRING = "items";
+static const QString ITEM_KEY_STRING  = "item";
 
 /// file naming
-static const QString ITEM_FILE_NAME = ITEM_KEY_STRING + ".json";
+static const QString ITEMS_FILE_NAME = ITEMS_KEY_STRING + ".json";
 
 /// functions
 static int GET_ROLE_FOR_COLUMN(const int column) {

model/modelitem.cpp

@@ -55,12 +55,25 @@ QString ModelItem::toString() const {
     // 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;
   // TODO add UUID and dates (entry, modification, end)
+  const UserRoles idRole = IdRole;
+  QVariant idValue       = data(idRole);
+  if (!idValue.isNull()) {
+    const QString idRoleName = ROLE_NAMES.value(idRole);
+    itemObject.insert(idRoleName, idValue.toString());
+  }
 
   QListIterator<UserRoles> i(USER_FACING_ROLES);
   while (i.hasNext()) {

model/modelitem.h

@@ -3,7 +3,7 @@
 
 #include <QVariant>
 
-typedef QHash<int, QVariant> ModelItemValues;
+typedef QMap<int, QVariant> ModelItemValues;
 
 class ModelItem {
  public:
@@ -18,7 +18,7 @@ class ModelItem {
   QJsonObject toJsonObject() const;
 
  private:
-  QHash<int, QVariant> m_values;
+  ModelItemValues m_values;
 };
 
 #endif  // MODELITEM_H

model/tablemodel.cpp

@@ -16,6 +16,7 @@ QByteArray TableModel::generateExampleItems() {
   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());
@@ -28,7 +29,7 @@ QByteArray TableModel::generateExampleItems() {
 
     array.append(itemObject);
   }
-  rootObject.insert(ITEM_KEY_STRING, array);
+  rootObject.insert(ITEMS_KEY_STRING, array);
 
   doc.setObject(rootObject);
   return doc.toJson();
@@ -49,16 +50,16 @@ QHash<int, QByteArray> TableModel::roleNames() const { return ROLE_NAMES; }
 
 int TableModel::rowCount(const QModelIndex& parent) const {
   if (parent.isValid()) {
-    return 0;  // no children
+    return 0;  /// no children
   }
   return m_items.size();
 }
 
 int TableModel::columnCount(const QModelIndex& parent) const {
   if (parent.isValid()) {
-    return 0;  // no children
+    return 0;  /// no children
   }
-  return ROLE_NAMES.size();
+  return USER_FACING_ROLES.size();
 }
 
 QVariant TableModel::data(const QModelIndex& index, int role) const {
@@ -82,9 +83,12 @@ QVariant TableModel::data(const QModelIndex& index, int role) const {
     case InfoRole:
     case AmountRole:
     case FactorRole:
+    case IdRole:
       return m_items.at(row)->data(role);
     case ToStringRole:
       return m_items.at(row)->toString();
+    case ToJsonRole:
+      return m_items.at(row)->toJsonObject();
   }
 
   return QVariant();
@@ -149,7 +153,7 @@ QJsonDocument TableModel::getAllItemsAsJsonDoc() const {
     QJsonObject itemObject = item->toJsonObject();
     array.append(itemObject);
   }
-  rootObject.insert(ITEM_KEY_STRING, array);
+  rootObject.insert(ITEMS_KEY_STRING, array);
 
   doc.setObject(rootObject);
   return doc;
@@ -168,6 +172,43 @@ QList<QStringList> TableModel::getItemsAsStringLists() const {
   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!";
@@ -191,7 +232,13 @@ void TableModel::appendItems(const QByteArray& jsonDoc) { insertItems(-1, jsonDo
 void TableModel::insertItems(int startPosition,
                              const QByteArray& jsonDoc,
                              const QModelIndex& parentIndex) {
-  const QList<ModelItemValues> valueList = JsonParser::toItemValuesList(jsonDoc, ITEM_KEY_STRING);
+  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);
 }
@@ -243,7 +290,7 @@ void TableModel::execEditItemData(const int row, const QMap<int, QVariant>& chan
     /// 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, ROLE_NAMES.size() - 1);
+    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());
@@ -284,3 +331,60 @@ bool TableModel::isEmptyValueEqualToZero(const int role) const {
     return false;
   }
 }
+
+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 (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

@@ -8,7 +8,7 @@ class ModelItem;
 
 using namespace std;
 
-typedef QHash<int, QVariant> ModelItemValues;
+typedef QMap<int, QVariant> ModelItemValues;
 
 class TableModel : public QAbstractTableModel {
   Q_OBJECT
@@ -38,6 +38,11 @@ class TableModel : public QAbstractTableModel {
   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;
@@ -66,6 +71,9 @@ class TableModel : public QAbstractTableModel {
   QMap<int, QVariant> onlyChangedValues(const QModelIndex& index,
                                         const QMap<int, QVariant>& roleValueMap) const;
   bool isEmptyValueEqualToZero(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