**Course Title:** Qt 6 Application Development with C++ **Section Title:** Model-View-Controller (MVC) Architecture in Qt **Topic:** Building a Qt application with custom models and views.(Lab topic) **Introduction** ------------ In this topic, we will explore how to create a Qt application using custom models and views. This lab topic will guide you through the process of designing and implementing a custom model and integrating it with a view to display data. We will also discuss best practices and provide examples to help you grasp the concepts. **Prerequisites** ------------ Before starting this lab, make sure you have a good understanding of the following topics: * Model-View-Controller (MVC) pattern in Qt * QAbstractListModel and QAbstractTableModel * Data binding between models and views **Custom Model** ------------- To create a custom model, we will derive a class from QAbstractTableModel or QAbstractListModel. For this example, we will use QAbstractTableModel. ### CustomTableModel.h ```cpp #ifndef CUSTOMTABLEMODEL_H #define CUSTOMTABLEMODEL_H #include <QAbstractTableModel> class CustomTableModel : public QAbstractTableModel { public: CustomTableModel(QObject *parent = nullptr); ~CustomTableModel(); // Header: QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override; // Basic functionality: int rowCount(const QModelIndex &parent = QModelIndex()) const override; int columnCount(const QModelIndex &parent = QModelIndex()) const override; QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override; // Editable: bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override; Qt::ItemFlags flags(const QModelIndex& index) const override; private: QVector<QVector<QString>> m_data; }; #endif // CUSTOMTABLEMODEL_H ``` ### CustomTableModel.cpp ```cpp #include "CustomTableModel.h" CustomTableModel::CustomTableModel(QObject *parent) : QAbstractTableModel(parent) { m_data = { {"John", "Doe"}, {"Jane", "Doe"} }; } CustomTableModel::~CustomTableModel() { } // Rest of the implementation... ``` **Custom View** ------------ To display the data provided by the custom model, we will use a QTableView. ### CustomView.h ```cpp #ifndef CUSTOMVIEW_H #define CUSTOMVIEW_H #include <QTableView> #include "CustomTableModel.h" class CustomView : public QTableView { public: CustomView(QWidget *parent = nullptr); ~CustomView(); void setModel(CustomTableModel *model); }; #endif // CUSTOMVIEW_H ``` ### CustomView.cpp ```cpp #include "CustomView.h" CustomView::CustomView(QWidget *parent) : QTableView(parent) { } CustomView::~CustomView() { } void CustomView::setModel(CustomTableModel *model) { QTableView::setModel(model); } ``` **Main Application** --------------- To test our custom model and view, we will create a simple application. ### main.cpp ```cpp #include <QApplication> #include <QMainWindow> #include "CustomView.h" int main(int argc, char *argv[]) { QApplication app(argc, argv); QMainWindow window; CustomView view(&window); CustomTableModel model(&window); view.setModel(&model); window.setCentralWidget(&view); window.show(); return app.exec(); } ``` **Best Practices and Takeaways** ------------------------------ * Always use QAbstractTableModel or QAbstractListModel as the base class for your custom models. * Make sure to override the necessary methods in your custom model class. * Use QTableView or QListView to display data provided by your custom model. * Always set the model for your view using the `setModel()` method. * Make sure to handle the memory management for your custom model and view. **Conclusion** ---------- In this lab topic, we explored how to create a Qt application using custom models and views. We designed and implemented a custom model and integrated it with a view to display data. We also discussed best practices and provided examples to help you grasp the concepts. **External Resources** * [Qt Documentation: Model-View Programming](https://doc.qt.io/qt-6/modelview.html) * [Qt Documentation: QAbstractTableModel](https://doc.qt.io/qt-6/qabstracttablemodel.html) * [Qt Documentation: QTableView](https://doc.qt.io/qt-6/qtableview.html) **Leave a Comment or Ask for Help** -------------------------------- If you have any questions or need help with the lab topic, feel free to leave a comment below. We will respond as soon as possible. Next topic: **Introduction to Qt's styling system and Qt Stylesheets (QSS)**.