Flet ToDo Tutorial

This tutorial demonstrates building a multi-platform To-Do application using the Flet framework in Python. It covers core Flet concepts and best practices.

Overview

**Goal:** Create a To-Do app deployable as a desktop, mobile, or web application.

**Technology:** Pure Python, Flet framework.

**Prerequisites:** Basic Python and OOP knowledge, Python 3.10+ installed, flet package installed.

**Codebase:** A single-file Python program (approx. 163 lines).

Core Concepts Covered

**App Setup:** Basic Flet app structure (ft.run(main)).

**UI Layout:** Using ft.Row and ft.Column for horizontal and vertical arrangement.

**Controls:** ft.TextField, ft.FloatingActionButton, ft.Checkbox, ft.Row, ft.Column, ft.IconButton, ft.TabBar, ft.Tabs.

**Event Handling:** Responding to user interactions (button clicks, tab changes, checkbox changes).

**Reusable UI Components:** Creating custom controls by subclassing ft.Control (e.g., TodoApp, Task classes).

**State Management:** Encapsulating state within custom controls.

**List Management:** Adding, editing, deleting, and filtering tasks.

**Filtering:** Implementing task filtering using ft.TabBar and ft.Tabs, leveraging before_update for visibility logic.

**Publishing:** Instructions to publish the app to various platforms.

Key Classes and Components

**Task Class:**

- Represents a single To-Do item. - Manages display (display_view) and edit (edit_view) states. - Handles Checkbox, TextField, IconButton (Edit, Delete, Save). - Properties: task_name, completed. - Callbacks: on_status_change, on_delete.

**TodoApp Class:**

- Root control for the To-Do application. - Contains TextField for new tasks, FloatingActionButton to add tasks, ft.Column for task list, and ft.Tabs for filtering. - Manages the collection of Task objects. - Handles adding new tasks, deleting tasks, and updating the UI. - Implements before_update to manage task visibility based on the selected filter.

Development Steps

1. **Installation:** Ensure Python 3.10+ and flet are installed. 2. **Basic App:** Create a hello.py with ft.Text and ft.run(main). 3. **Adding Controls:** Implement TextField and FloatingActionButton to add basic tasks. 4. **Page Layout:** Use Row and Column to structure the UI, setting page.horizontal_alignment. 5. **Reusable Components:** Refactor UI into TodoApp and Task classes. 6. **Edit/Delete:** Add functionality to edit and delete tasks within the Task component. 7. **Filtering:** Integrate TabBar and Tabs to filter tasks (all, active, completed). 8. **Final Touches:** (Implied, not fully detailed in provided text, but mentioned in summary) Add footer elements like task count and clear completed button. 9. **Publishing:** Follow Flet's documentation for deployment.

Platform Support

Web

Desktop (Linux, macOS, Windows)

Mobile (Android, iOS)

Further Resources

[Flet Controls](https://docs.flet.dev/controls/)

[Flet Examples](https://github.com/flet-dev/flet/tree/main/sdk/python/examples)

[Flet Publishing Guide](https://docs.flet.dev/publish/)