PyQt6 and Databases: Building a Todo App with QtSql

• 0:00 Introduction: Following up on a popular request, this video demonstrates building a more advanced PyQt6 desktop application integrated with an SQL database. The app will allow users to manage a todo list.
• 0:30 QtSql Module: Introduction to PyQt6's QtSql module, which enables integration with SQL databases. Key classes discussed include QSqlDatabase for connections and QSqlQuery for executing queries. The pronunciation of PyQt (as "py-cute") is also clarified.
• 1:38 Creating the Database: An SQLite database named "todos.sqlite" is created. A "todos" table is created within the database with columns for ID (primary key), name (varchar), and completed (boolean). The VS Code SQLite extension is recommended for database visualization.
• 3:13 Database Connection: A Python function open_connection is defined to establish and close the database connection using QSqlDatabase. The function returns True if the connection is successful. The code is later moved to a separate db.py module for better organization.
• 8:36 MainWindow: A MainWindow class is created, inheriting from QtWidgets.QMainWindow. This class sets up the main application window, including the title and central widget. The open_connection function is called before creating the window to ensure data availability.
• 11:48 Todo Form Widget: A TodoForm widget is created in create_todo.py, inheriting from QtWidgets.QWidget. This widget contains input fields for the todo name (QLineEdit), a checkbox for completion status (QCheckBox), and a submit button (QPushButton).
• 18:47 Todo Table Widget: A TodoTable widget is created in todo_table.py, also inheriting from QtWidgets.QWidget. This widget uses a QTableWidget to display the todo items. Columns are set for "Todo Name" and "Completed?".
• 21:58 Form Submission and Database Interaction: The submit_todo method in TodoForm handles form submission. It retrieves user input, constructs an SQL insert query using QSqlQuery.prepare (to prevent SQL injection), binds the values, and executes the query. A success message (QMessageBox) is displayed upon successful insertion, and the input fields are cleared. A warning message is displayed if the user doesn't enter a todo name.
• 27:19 Updating the Table on Submit: A callback mechanism is implemented to update the TodoTable whenever a new todo is submitted. The add_todo_to_list method in MainWindow acts as an intermediary, calling the add_todo_item method of TodoTable.
• 34:30 Populating the Table on Load: The get_todos method in TodoTable is called within the __init__ method to populate the table with existing database entries when the application starts. It fetches data using a select query and iterates through the results, adding each item to the QTableWidget. The completed status is converted from a boolean to "Completed" or "Pending" for display.