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:

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

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:

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:

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)