Using CanExecute in RelayCommand MVVM Toolkit

Question

I have bound button command to one RelayCommand from MVVM Toolkit, which executes some function, with following:

[RelayCommand]
private async void SomeMethod() {}

I want to prevent multiple clicks on the button hence, preventing multiple method calls via CanExecute parameter of RelayCommand, but I can't figure that one out.

I know that RelayCommand first checks with CanExecute if it is possible to execute the command, but I do not understand how to go about implementing it.

I have searched numerous questions on the topic but could get nowhere near to solution.

Edit: Also there is no SomeMethod.isRunning property.

Hakan Fıstık · Accepted Answer · 2023-11-05 17:44:17Z

14

To implement CanExecute, You can try the following example:

[RelayCommand(CanExecute = nameof(IsSomeMethodExcutable))]
private async void SomeMethod(){}

private bool IsSomeMethodExcutable() { return _isBusy;}

edited Nov 5, 2023 at 17:44

Hakan Fıstık

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answered Dec 18, 2022 at 6:30

hugebug4ever

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1 Comment

ggrewe1959 Over a year ago

I believe that this should be the accepted answer. The RelayCommand has the correct signature private async void and adding the CanExecute parameter specifies the method to call when the CanExecute state changes. The only other thing needed is to call SomeMethodCommand.NotifyCanExecuteChanged(); in a method that changes the state of _isBusy

Corentin Pane · Accepted Answer · 2024-10-15 12:54:40Z

3

To specifically answer your need:

I want to prevent multiple clicks on the button

you can use the AllowConcurrentExecution parameter of the RelayCommand attribute:

[RelayCommand(AllowConcurrentExecutions = false)]
private async Task SomeMethod()
{
    await Task.Delay(1000); // Perform real stuff here
}

answered Oct 15, 2024 at 12:54

Corentin Pane

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2 Comments

Shimmy Weitzhandler Apr 22 at 4:30

The default value of AllowConcurrentExecution is false.

Corentin Pane Apr 23 at 8:42

That is correct, mentioned in docs here learn.microsoft.com/en-us/dotnet/communitytoolkit/mvvm/…. The issue OP had was probably related to the async void signature (which I inadvertently fixed).

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