Added a ModelSummary class to make the overview over the model content accessible via QProperty system & a SummaryWidget to show this information. Only property rowCount as a proof of concept. Other properties will follow.

libs/BeetRoundCore/model/modelsummary.cpp

@@ -0,0 +1,22 @@
+#include "modelsummary.h"
+
+#include "tablemodel.h"
+
+ModelSummary::ModelSummary(std::shared_ptr<TableModel> model, QObject* parent)
+    : QObject(parent)
+    , m_model(model) {
+  Q_ASSERT(model);
+  connect(m_model.get(), &TableModel::rowCountChanged, this, &ModelSummary::rowCountChanged);
+}
+
+ModelSummary::~ModelSummary() {}
+
+int ModelSummary::rowCount() const {
+  const int nRows = m_model->rowCount();
+  return nRows;
+}
+
+QBindable<int> ModelSummary::bindableRowCount() {
+  m_rowCount = m_model->rowCount();
+  return &m_rowCount;
+}

libs/BeetRoundCore/model/modelsummary.h

@@ -0,0 +1,32 @@
+#ifndef MODELSUMMARY_H
+#define MODELSUMMARY_H
+
+#include <QObject>
+#include <QProperty>
+
+class TableModel;
+
+using namespace std;
+
+class ModelSummary : public QObject {
+  Q_OBJECT
+
+  Q_PROPERTY(int rowCount READ rowCount NOTIFY rowCountChanged BINDABLE bindableRowCount)
+
+ public:
+  ModelSummary(shared_ptr<TableModel> model, QObject* parent = nullptr);
+  ~ModelSummary();
+
+  int rowCount() const;
+  QBindable<int> bindableRowCount();
+
+ signals:
+  void rowCountChanged();
+
+ private:
+  shared_ptr<TableModel> m_model;
+
+  Q_OBJECT_BINDABLE_PROPERTY(ModelSummary, int, m_rowCount, &ModelSummary::rowCountChanged);
+};
+
+#endif  // MODELSUMMARY_H

libs/BeetRoundCore/model/tablemodel.cpp

@@ -46,7 +46,10 @@ QByteArray TableModel::generateExampleItems() {
 
 TableModel::TableModel(QUndoStack* undoStack, QObject* parent)
     : QAbstractTableModel{parent}
-    , m_undoStack(undoStack) {}
+    , m_undoStack(undoStack) {
+  connect(this, &TableModel::rowsInserted, this, &TableModel::onRowCountChanged);
+  connect(this, &TableModel::rowsRemoved, this, &TableModel::onRowCountChanged);
+}
 
 Qt::ItemFlags TableModel::flags(const QModelIndex& index) const {
   if (!index.isValid()) {
@@ -279,6 +282,16 @@ void TableModel::insertItems(int startPosition,
   m_undoStack->push(insertCommand);
 }
 
+void TableModel::onRowCountChanged(const QModelIndex& parent, int first, int last) {
+  Q_UNUSED(first);
+  Q_UNUSED(last);
+
+  if (parent != QModelIndex()) {
+    return;
+  }
+  emit rowCountChanged();
+}
+
 void TableModel::execInsertItems(const int firstRow, const QList<ModelItemValues> valueList) {
   const int nRows = valueList.size();
   qDebug() << "Inserting" << nRows << "items...";

libs/BeetRoundCore/model/tablemodel.h

@@ -2,6 +2,7 @@
 #define TABLEMODEL_H
 
 #include <QAbstractTableModel>
+#include "metadata.h"
 
 class QUndoStack;
 class ModelItem;
@@ -55,6 +56,12 @@ class TableModel : public QAbstractTableModel {
                    const QList<ModelItemValues>& itemValuesList,
                    const QModelIndex& parentIndex = QModelIndex());
 
+ signals:
+  void rowCountChanged();
+
+ private slots:
+  void onRowCountChanged(const QModelIndex& parent, int first, int last);
+
  private:
   /// *** members ***
   // TODO shared_ptr -> unique_ptr