Creating a new Flet app - Flet

import TabItem from '@theme/TabItem'; import Tabs from '@theme/Tabs';

Create a new directory (or directory with pyproject.toml already exists if initialized with a project manager) and switch into it.

To create a new "minimal" Flet app run the following command:

<Tabs groupId="uv--pip"> <TabItem value="uv" label="uv"> ```bash uv run flet create ``` </TabItem> <TabItem value="pip" label="pip"> ```bash flet create ``` </TabItem> </Tabs> :::danger[Important] Any existing `README.md` or `pyproject.toml` (for example, created by `uv init`) will be replaced by the one created by [`flet create`](../cli/flet-create.md) command. :::

The command will create the following directory structure:

tree

README.md
pyproject.toml
src
    assets
        icon.png
    main.py # (1)!
storage
    data
    temp

Contains a simple Flet program. It has main() function where you would add UI elements (controls) to a page or a window. The application ends with a ft.run() function which initializes the Flet app and runs main().

You can find more information about flet create command here.

Auto-update

Flet automatically calls page.update() (or .update() on the nearest isolated ancestor) at the end of every event handler and main() function. This means you don't need to call .update() yourself in most cases:

python

import flet as ft

def main(page: ft.Page):
    def button_click(e):
        page.controls.append(ft.Text("Clicked!"))
        # no need to call page.update() — it happens automatically

    page.controls.append(ft.Button("Click me", on_click=button_click))
    # no need to call page.update() here either

ft.run(main)

:::note[Note] If your event handler already calls .update() explicitly (e.g. code written for Flet 0.x), the automatic update is skipped to avoid a redundant double update. :::

Disabling auto-update

You can disable auto-update for fine-grained control over when updates are sent to the client. Use ft.context.disable_auto_update() and ft.context.enable_auto_update() to toggle the behavior.

When called inside a handler, the setting applies to the current handler context only:

python

import flet as ft

def main(page: ft.Page):
    def add_many_items(e):
        ft.context.disable_auto_update()
        for i in range(100):
            page.controls.append(ft.Text(f"Item {i}"))
        page.update()  # single update for all 100 items

    page.controls.append(ft.Button("Add items", on_click=add_many_items))

ft.run(main)

When called outside of event handlers (e.g. at the module level), it controls the global default for the entire app:

python

import flet as ft

# disable auto-update globally
ft.context.disable_auto_update()

def main(page: ft.Page):
    def button_click(e):
        page.controls.append(ft.Text("Clicked!"))
        page.update()  # must call explicitly since auto-update is off

    page.controls.append(ft.Button("Click me", on_click=button_click))
    page.update()

ft.run(main)

Now let's see Flet in action by running the app!