C#•2y ago

✅ RelayCommand CanExecute MVVM

Hi, I'm using this nuget

CommunityToolkit.Mvvm.Input

CommunityToolkit.Mvvm.Input

CommunityToolkit.Mvvm.Input

CommunityToolkit.Mvvm.Input to add my relaycommand.
i've set CanExecute this way =>

AddThickCommand = new RelayCommand(AddThickCommand_Execute, () => CanAddThickness);

AddThickCommand = new RelayCommand(AddThickCommand_Execute, () => CanAddThickness);

AddThickCommand = new RelayCommand(AddThickCommand_Execute, () => CanAddThickness);

AddThickCommand = new RelayCommand(AddThickCommand_Execute, () => CanAddThickness);

My problem there is that canexecute is trigger only when i declare

AddThickCommand

AddThickCommand

AddThickCommand

AddThickCommand and canexecute is never raised again even if the boolean

CanAddThickness

CanAddThickness

CanAddThickness

CanAddThickness change.

I'd like to update canexecute each time

CanAddThickness

CanAddThickness

CanAddThickness

CanAddThickness change to enable or not the button. Any idea why this don't work with this package ?

Pobiega•1/30/24, 9:11 AM

You need to notify the command that the bool has changed

Pobiega•1/30/24, 9:11 AM

IRelayCommand.NotifyCanExecuteChangedIRelayCommand.NotifyCanExecuteChanged

Pobiega•1/30/24, 9:12 AM

Since you are already using CommunityToolkit.Mvvm, you could use the source generated version of this to get all this "for free"

Pobiega•1/30/24, 9:14 AM

internal partial class TestViewModel : ObservableObject
{
    [RelayCommand(CanExecute = nameof(CanAddThickness))]
    private void AddThickness()
    {
    }

    [ObservableProperty]
    [NotifyCanExecuteChangedFor(nameof(AddThicknessCommand))]
    private bool canAddThickness;
}

internal partial class TestViewModel : ObservableObject
{
    [RelayCommand(CanExecute = nameof(CanAddThickness))]
    private void AddThickness()
    {
    }

    [ObservableProperty]
    [NotifyCanExecuteChangedFor(nameof(AddThicknessCommand))]
    private bool canAddThickness;
}

Pobiega•1/30/24, 9:15 AM

this would add a AddThicknessCommandAddThicknessCommand public property that has a CanExecuteCanExecute that depends on the

CanAddThickness

CanAddThickness

observable property. When that property changes, the command will re-evaluate if it can execute or not.

ElioOP•1/30/24, 9:25 AM

oh didn't know we could add anotations with this nuget i'll take a look thanks !!

Pobiega•1/30/24, 9:28 AM

yea the source generator for it is... amazing

Pobiega•1/30/24, 9:28 AM

it writes all the boilerplate code for you

ElioOP•1/30/24, 10:37 AM

that is a bit tricky cause some code aren't wrote and you need to know that the properties is automatically generated, it will be perfect after sometime using it. Thanks !

✅ RelayCommand CanExecute MVVM

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