Tutorials: Learn Flet

 

Flet is an incredible choice if you want to build beautiful, interactive apps quickly.

If you already know a little Python, Flet lets you build web, desktop, and mobile apps without needing to learn HTML, CSS, or JavaScript. It handles the frontend for you using Flutter (a powerful UI engine by Google), but you get to write everything in clean, simple Python code.

1. Get Your Environment Ready

Before you can write Flet code, you need to install it. Make sure you have Python installed on your computer, open your terminal or command prompt, and run:

Bash

pip install flet

2. Your Very First Flet App

The best way to learn is by seeing how the code pieces together. Create a file named app.py and paste the following code inside it. This app creates a simple text label and a button that increments a counter.

Python

import flet as ft

def main(page: ft.Page):
    # Set the title of your application window
    page.title = "My First Flet App"
    
    # Create a text element to display our count
    count_text = ft.Text(value="0", size=30)

    # Define what happens when the button is clicked
    def button_clicked(e):
        # Convert the current text to an integer, add 1, and update it
        count_text.value = str(int(count_text.value) + 1)
        # You must always call page.update() to refresh the UI changes!
        page.update()

    # Add controls (widgets) directly to the page layout
    page.add(
        ft.Row(
            [
                ft.IconButton(ft.icons.REMOVE, on_click=lambda _: print("Minus clicked")),
                count_text,
                ft.ElevatedButton("Click to Increase", on_click=button_clicked)
            ],
            alignment=ft.MainAxisAlignment.CENTER,
        )
    )

# Run the application
ft.app(target=main)

To run it, type python app.py in your terminal. A desktop window will instantly pop up with your working application!

3. The 3 Golden Rules of Flet

As you start practicing, keep these three structural rules in mind:

1. The Page is Your Canvas: Everything you want the user to see must be added to the page object using page.add().

2. Controls are Your Building Blocks: In Flet, UI elements (buttons, text fields, checkboxes) are called "Controls". You arrange them using structural layouts like ft.Row() (horizontal) and ft.Column() (vertical).

3. Never Forget page.update(): When you change a property in your Python code (like changing a text string or a background color), the screen won't change until you explicitly tell Flet to refresh by calling page.update().

4. Best Resources to Keep Learning

• The Official Documentation (flet.dev): This is your holy grail. Their "Controls Reference" section shows you exactly how to use every single visual asset available (inputs, charts, navigation bars, cards) with copy-and-paste code examples.

• Flet Gallery: Look through the official Flet gallery online. It contains dozens of pre-built UI dashboards and components so you can see exactly how complex layouts are structured.

• Build a Todo App: The ultimate beginner milestone in Flet is building a simple Todo list app. It forces you to learn how to handle text inputs, lists of items, and delete buttons.

5. Resurse: