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c# - [UWP/MVVM]Enable/Disable Button in RadDataGrid Data Template Column that have commands bound to them upon conditions

I have set a bool property and have bound it to the IsEnabled in the xaml but the ICommand CanExecute method overrides the IsEnabled in xaml, so my bool property is ineffective.

When I define the conditions within the CanExecute method in the view model, It either disables all buttons in which the method is bound to, or enables all of them.

Its a grid that displays 3 different buttons for each row, and each button goes to a new xaml screen. If there is no data for the particular condition on the row the button is on then the button needs to be disabled.

How do i go about setting this so that buttons are disabled upon a condition?

Custom Command:

public class CustomCommand : ICommand
{

    private Action<object> execute;
    private Predicate<object> canExecute;
    public CustomCommand(Action<object> execute, Predicate<object> canExecute)
    {
        this.execute = execute;
        this.canExecute = canExecute;

    }

    public event EventHandler CanExecuteChanged
    {
        add
        {

        }
        remove
        {

        }
    }

    public bool CanExecute(object parameter)
    {
        //throw new NotImplementedException();
        bool b = canExecute == null ? true : canExecute(parameter);
        return b;
    }

    public void Execute(object parameter)
    {
        execute(parameter);
    }
}

xaml

<DataTemplate>
                                <Button Command="{Binding Source={StaticResource VM},
                                Path=Command}" CommandParameter="{Binding}" >
                                    <SymbolIcon Symbol="Edit" Foreground="AliceBlue" />
                                </Button>
</DataTemplate>

CanExecute in VM

 private bool CanGetDetails(object obj)
    {
        return true;
    }
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1 Reply

0 votes
by (71.8m points)

I think you can pick a lot of code from the RelayCommand of MVVMLight. Try to change your event to

    public event EventHandler CanExecuteChanged
    {
        add
        {
            if (canExecute != null)
            {
                CommandManager.RequerySuggested += value;
            }
        }

        remove
        {
            if (canExecute != null)
            {
                CommandManager.RequerySuggested -= value;
            }
        }
    }

and add also a function

    public void RaiseCanExecuteChanged()
    {
        CommandManager.InvalidateRequerySuggested();
    }

Then, whatever you put as your Predicate on the command, at the Predicate's boolean setter do:

SomeCustomCommand.RaiseCanExecuteChanged()

Hope I helped.


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