[Question] Update all text in the application without restarting

[proDreams]

Question

Greetings. I'm trying to make a GUI for my small application and ran into a problem.
My application is designed to work in two languages.
Actually, this is the question:
There is a drop-down menu with a choice of display language. The user selects a language.
The choice is written to a variable.
How can I update all text in the application without restarting?
What would they be updated according to the new value?

Below is the code, but I just started to understand Flet and don't understand a lot.

Code sample

import flet as ft

from app import text_constants


def main(page: ft.Page):
    def settings_route(e):
        page.route = "/settings"
        page.add(ft.Text(f"New route: {page.route}"))
        page.update()

    def app_bar(title: str = "PoETRY"):
        return ft.AppBar(
            title=ft.Text(title),
            center_title=False,
            bgcolor=ft.colors.SURFACE_VARIANT,
            actions=[
                ft.IconButton(ft.icons.SETTINGS, on_click=settings_route),
            ],
        )

    def route_change(route):
        page.views.clear()
        page.views.append(
            ft.View(
                "/",
                [
                    app_bar(),
                    ft.ElevatedButton("Валюта", on_click=lambda _: page.go("/валюта")),
                ],
            )
        )
        if page.route == "/валюта":
            page.views.append(
                ft.View(
                    "/валюта",
                    [
                        app_bar("Валюта"),
                        ft.ElevatedButton("Go Home", on_click=lambda _: page.go("/")),
                    ],
                )
            )
        if page.route == "/settings":
            page.views.append(
                ft.View(
                    "/settings",
                    [
                        app_bar("Settings"),
                        ft.Row(
                            [
                                ft.Container(
                                    ft.Column(
                                        [ft.Text(text_constants.settings_language_text[text_constants.current_lang][0],
                                                 size=18, weight="bold"),
                                         ft.Divider(),
                                         ft.Text('Выбрать язык:'),
                                         lang_dd,
                                         ],
                                        horizontal_alignment=ft.CrossAxisAlignment.CENTER,
                                    ),
                                    bgcolor=ft.colors.SURFACE_VARIANT,
                                    height=300,
                                    width=300,
                                    border_radius=10,
                                    padding=20
                                ),
                            ],
                            alignment="center"
                        )
                    ],
                )
            )
            page.update()

    def view_pop(view):
        page.views.pop()
        top_view = page.views[-1]
        page.go(top_view.route)

    def change_lang(e):
        text_constants.current_lang = lang_dd.value
        print(text_constants.settings_language_text[text_constants.current_lang][0])
        print(text_constants.current_lang)
        page.update()

    lang_dd = ft.Dropdown(
        width=200,
        options=[
            ft.dropdown.Option(key="ru", text="Русский"),
            ft.dropdown.Option(key="en", text=text_constants.settings_language_text[text_constants.current_lang][2]),
        ],
        border_radius=5,
        on_change=change_lang
    )

    page.on_route_change = route_change
    page.on_view_pop = view_pop
    page.go(page.route)

Error message

-

------------------------------------------------------

• I have searched for answers to my question both in the issues and in previous discussions.

[fsmosca]

I tried your code and got this:

from app import text_constants
ModuleNotFoundError: No module named 'app'

Could you provide a minimal reproducible code to demonstrate your issue.?

[proDreams]

https://github.com/proDreams/PoE-IPC here code.
The program has two languages and text options for them. I figured out how to update specific lines when data changes, I'm interested in how to update all text in the program without restarting. Or forced to redraw the interface.