How to enable/disable binding?

[yikaifeng]

Is it possible to enable/disable an existed binding? How to do that?

BINDINGS = [
        ("r", "refresh", "Refresh"),
        ("a", "add_user", "Add"),
        ("d", "delete_user", "Delete"),
    ]

I'd like to disable/enable Delete depending on some event. I got that binding by self.active_bindings.get('d'), but can't find method or property for disable

[ddkasa]

You can implement a check_action method. Just return False or None depending on the action, and it will disable the Binding.

https://textual.textualize.io/guide/actions/#dynamic-actions
https://textual.textualize.io/api/dom_node/#textual.dom.DOMNode.check_action

[ddkasa]

Just to check my assumption is that your custom BaseScreen is calling custom_compose inside the default compose method? Otherwise that's ignored in the default Textual Screen implementation.

It would still be useful if you reduced the code to the minimum though, as this still has to many variables, preferably something that is runnable without modification.

[yikaifeng]

Just to check my assumption is that your custom BaseScreen is calling custom_compose inside the default compose method?

Yes, it's calling. The same code on this screen for getting tab and row index works in events

@on(TabbedContent.TabActivated)
def on_tab_activated(self, event: TabbedContent.TabActivated) -> None:
    self.on_tab_changed_or_row_selected()
    
        
@on(DataTable.RowSelected)
def on_users_row_selected(self, event: DataTable.RowSelected) -> None:
    self.on_tab_changed_or_row_selected()
        
    
def on_tab_changed_or_row_selected(self) -> None:
    tab = "users" if "1" in self.query_one(TabbedContent).active else "groups"
    if tab == "users":
        table = self.query_one("#users_datatable", DataTable)
        row_idx = table.cursor_row
    else:
        table = self.query_one("#groups_datatable", DataTable)
        row_idx = table.cursor_row
    logger.info(f"tab {tab}, idx {row_idx}")
    self.query_one("#log", GlobalRichLog).refresh_logs()

I'll try to reduce code to detect problem

[edward-jazzhands]

@yikaifeng Just a quick tip about what minimal example means - An MRE should preferably be a block of code that we can copy and paste to run on our own computers, and it absolutely can't use custom classes in it. If you use a custom class like BaseScreen as you did in the above example, we cant run that on our own computers and we have no way of knowing what that class contains.

For a guide on how to write a proper MRE, please see "The Art of the Minimal Reproducible Example" header that is displayed at the top of the main Discussions page

[yikaifeng]

Here it is (Error: NoMatches: No nodes match <class 'textual.widgets._switch.Switch'> on MyScreen()):

import typing as ty

from textual.app import ComposeResult, App
from textual.screen import Screen
from textual.containers import Vertical
from textual.widgets import Footer, Label, Switch

#===============================================================================
class MyScreen(Screen):
    
    BINDINGS = [
        ("m", "toggle_menu", "Toggle menu"),
        ("l", "toggle_log", "Toggle log"),
        ("w", "w_pressed", "w pressed"),
        ("e", "e_pressed", "e pressed"),
    ]
    
    def compose(self) -> ComposeResult:
        
        yield Footer()
        
        with Vertical(id="main_container"):
            yield Label("Hello world")
            yield Switch()
            
    
    def check_action(self, action: str, parameters: ty.Tuple[object, ...]) -> ty.Optional[bool]:
        if action in ["toggle_log", "w_pressed"]:
            if self.query_one(Switch).value:
                return None
            else:
                return True
        else:
            return True


#===============================================================================
class MyApp(App):
    
    SCREENS = {
        "myscreen": MyScreen,
    }
    

    def compose(self) -> ComposeResult:
        yield Label("Start screen")
        yield Footer()
        
        
    def on_mount(self):
        self.push_screen("myscreen")
        
        
#===============================================================================
if __name__ == "__main__":
    app = MyApp()
    app.run()

[willmcgugan]

check_action may be called before that widget has been composed. You will need to handle the NoMatches exception.