**Course Title:** PyQt6 Application Development **Section Title:** Understanding the Model-View-Controller (MVC) Pattern **Topic:** Developing a custom model-based app with list and table views.(Lab topic) **Overview** In the previous topics, we've covered the basics of the Model-View-Controller (MVC) pattern in PyQt6, including working with models and data binding between models and views. In this lab topic, we'll apply our knowledge by developing a custom model-based application that uses list and table views to display data. We'll create a simple address book application that allows users to add, edit, and delete contacts. **Requirements** Before we begin, ensure that you have the following: * PyQt6 installed on your system (you can download it from [https://www.riverbankcomputing.com/software/pyqt/download](https://www.riverbankcomputing.com/software/pyqt/download)) * A code editor or IDE of your choice (such as PyCharm, Visual Studio Code, or Sublime Text) **Designing the Model** Our address book application will use a custom model to store contact data. We'll create a `Contact` class to represent individual contacts and a `ContactModel` class to manage the collection of contacts. ```python # contact.py class Contact: def __init__(self, name, email, phone): self.name = name self.email = email self.phone = phone class ContactModel: def __init__(self): self.contacts = [] def add_contact(self, contact): self.contacts.append(contact) def remove_contact(self, contact): self.contacts.remove(contact) def get_contacts(self): return self.contacts ``` **Implementing the View** Our application will use two views: a `ListView` to display a list of contacts and a `TableView` to display contact details. ```python # list_view.py from PyQt6.QtWidgets import QListView, QAbstractItemView from PyQt6.QtCore import QAbstractListModel, Qt class ContactListModel(QAbstractListModel): def __init__(self, contact_model, parent=None): super().__init__(parent) self.contact_model = contact_model def rowCount(self, parent=None): return len(self.contact_model.get_contacts()) def data(self, index, role=Qt.ItemDataRole.DisplayRole): if role == Qt.ItemDataRole.DisplayRole: contact = self.contact_model.get_contacts()[index.row()] return contact.name class ListView(QListView): def __init__(self, contact_model): super().__init__() self.setModel(ContactListModel(contact_model)) self.setSelectionMode(QAbstractItemView.SelectionMode.SingleSelection) # table_view.py from PyQt6.QtWidgets import QTableView, QAbstractItemView from PyQt6.QtCore import QAbstractTableModel, Qt class ContactTableModel(QAbstractTableModel): def __init__(self, contact_model, parent=None): super().__init__(parent) self.contact_model = contact_model def rowCount(self, parent=None): return len(self.contact_model.get_contacts()) def columnCount(self, parent=None): return 3 def data(self, index, role=Qt.ItemDataRole.DisplayRole): if role == Qt.ItemDataRole.DisplayRole: contact = self.contact_model.get_contacts()[index.row()] if index.column() == 0: return contact.name elif index.column() == 1: return contact.email elif index.column() == 2: return contact.phone class TableView(QTableView): def __init__(self, contact_model): super().__init__() self.setModel(ContactTableModel(contact_model)) self.setSelectionMode(QAbstractItemView.SelectionMode.SingleSelection) ``` **Putting it all together** Now that we have our model, list view, and table view, let's create the main application window. ```python # main.py from PyQt6.QtWidgets import QApplication, QMainWindow, QSplitter, QVBoxLayout, QWidget from PyQt6.QtCore import Qt from contact import ContactModel from list_view import ListView from table_view import TableView class AddressBook(QMainWindow): def __init__(self): super().__init__() self.contact_model = ContactModel() self.list_view = ListView(self.contact_model) self.table_view = TableView(self.contact_model) splitter = QSplitter(Qt.Orientation.Horizontal) list_widget = QWidget() list_widget.setLayout(QVBoxLayout()) list_widget.layout().addWidget(self.list_view) table_widget = QWidget() table_widget.setLayout(QVBoxLayout()) table_widget.layout().addWidget(self.table_view) splitter.addWidget(list_widget) splitter.addWidget(table_widget) self.setCentralWidget(splitter) if __name__ == "__main__": import sys app = QApplication(sys.argv) address_book = AddressBook() address_book.show() sys.exit(app.exec()) ``` **Conclusion** In this lab topic, we've developed a custom model-based application that uses list and table views to display contact data. We've designed a simple address book application that allows users to add, edit, and delete contacts. This example demonstrates how to apply the MVC pattern in PyQt6 to create complex, data-driven applications. **Exercise** * Add functionality to add, edit, and delete contacts. * Use a database to persist contact data. **What's next?** In the next topic, we'll learn about Qt Stylesheets for customizing UI. If you have any questions or need help with this topic, please leave a comment below.