Wait for result of modal screen

[ghost]

How do you wait for the result of a modal screen before continuing?

E.g. the following code does not wait:

    async def action_reschedule_all(self):
        """Reschedule all Jobs"""
        if not self.app.is_logged_in:
            await self.app.push_screen("login")
        self.log("################")
```

[davep]

Textual has a way to pass a callback into a screen, and have the screen return the result. It's a fairly recent addition which we've been testing out and so it still needs to be documented -- you can see an example in the PR that added the feature.

To see it in action in a real application, see the YesNo dialog in Frogmouth and then see it being used to add a yes/no confirmation around deleting something (in this case a bookmark).

[ghost]

Thanks for the answer, was able to work things out thanks to it!

[mzebrak]

@davep Could you tell me if there are any plans for this feature? I mean not passing a callback to the modal screen but instead just awaiting its result or somehow blocking the execution of further code until the screen closes (asyncio.Event?, asyncio.Lock?).

I have some business logic separated into a Command pattern. This is to be reusable in TUI as well as external CLI. There are some commands that require the user to log in, so such a command takes a callback to the login functionality. In the case of a TUI, it corresponds with pushing a login screen. At this point I don't see any possibility to return the result from the command when it is called like:

SomeCommand.register_activate_callback(lambda: self.app.push_screen(LoginScreen()))
some_command = SomeCommand()

result = some_command.execute()  # This is not possible since inside the execute method, LoginScreen is pushed and we can't wait till it closes (also probably that should be `await some_command.execute()`
some_further_logic(result)

and instead, we handle this by implementing the Observer pattern so someone could subscribe to the result, but it complicates the simple execution of such a command.

SomeCommand.register_activate_callback(lambda: self.app.push_screen(LoginScreen()))
some_command = SomeCommand()

def __on_result(result, exception):
    # We need to react to the result here
    some_further_logic(result)
    pass

some_command.observe_result()

Maybe it's not a big inconvenience at the moment, but I think that waiting for the result would improve a lot. I don't think working with lots of callbacks is great. I am waiting for your reply to know what you think.

[davep]

Could you tell me if there are any plans for this feature? I mean not passing a callback to the modal screen but instead just awaiting its result or somehow blocking the execution of further code until the screen closes

None that I'm aware of.