Chat tutorial - Flet

Flet Chat Tutorial

This tutorial details the creation of a real-time, in-memory chat application using the Flet framework in Python.

Core Concepts

**Flet Basics:** Creating a basic Flet app with ft.Page and ft.run().

**UI Controls:** Utilizes Column, Text, TextField, Button, Row, AlertDialog, CircleAvatar, ListView, Container, and IconButton for UI construction.

**Event Handling:** Implements event handlers like on_click and on_submit for user interactions.

**Real-time Communication:** Leverages Flet's built-in PubSub library for broadcasting messages across multiple client sessions.

**Custom Controls:** Demonstrates creating a reusable ChatMessage control inheriting from ft.Row to format messages with user avatars and names.

**Session Management:** Uses page.session.store for persisting user names across sessions.

**User Experience Enhancements:** Incorporates features like autofocus, shift_enter for keyboard input, auto_scroll for message visibility, and customizable page titles.

Key Features Implemented

**Message Display:** ListView to show chat history, with ChatMessage custom controls for individual messages.

**Message Input:** TextField for typing messages, with IconButton for sending.

**User Identification:** AlertDialog to prompt users for their name upon joining.

**Message Broadcasting:** page.pubsub.subscribe and page.pubsub.send_all for real-time updates.

**Message Types:** Differentiates between chat_message and login_message.

**Layout:** Uses Container for borders and expand property for flexible layout.

**Keyboard Support:** autofocus, on_submit, and shift_enter for seamless input.

**Scrolling:** auto_scroll=True on ListView for automatic scrolling to new messages.

Code Structure

**Message Dataclass:** Defines message structure (user_name, text, message_type).

**ChatMessage Control:** Custom ft.Row subclass for message formatting.

**main Function:** Initializes the Flet app, sets up controls, event handlers, and PubSub subscriptions.

**ft.run(main):** Executes the Flet application.

Deployment

Instructions are provided to deploy the Flet app as a web application, referencing external hosting platforms like Fly.io or Replit.

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