CommandParameter Binding Resolves after Command.CanExecute Fires

Question

I have a button with a bound command and command parameter:

    <Button Margin="5,0,5,5" Style="{StaticResource MainButton}" Grid.Row="2" Grid.RowSpan="2" Grid.Column="3" Padding="0">
         <Button.CommandParameter>
              <MultiBinding Converter="{StaticResource SwapArgsConverter}" ConverterParameter="-1">
                   <Binding RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType=tlq:SmartWarningsWindow}" Path="DataContext.SelectedWarning"></Binding>
                   <Binding Path="Rank"></Binding>
              </MultiBinding>
         </Button.CommandParameter>
         <Button.Command>
              <Binding RelativeSource="{RelativeSource FindAncestor, AncestorType=tlq:SmartWarningsWindow}" Path="DataContext.SwapCommand"></Binding>
         </Button.Command>
     </Button>

The bindings all work fine, but the Command binding resolves, and the ICommand.CanExecute method fires before the CommandParameter binding resolves. This is causing my control to be incorrectly disabled when the window loads.

I have tried several things, including placing the Command Binding after the CommandParameter binding like you see above (originally the command binding was an attribute).

Does anyone know a way to force the CommandParameter binding to resolve first?

Have you tried to re query in your command class?

Olaru Mircea
– Olaru Mircea

2015-06-12 20:52:02 +00:00
Commented Jun 12, 2015 at 20:52 — Olaru Mircea
– Olaru Mircea, Commented Jun 12, 2015 at 20:52

Olaru Mircea · Accepted Answer · 2015-06-12 20:55:58Z

1

You might be missing this in your command class:

public event EventHandler CanExecuteChanged
{
    add { CommandManager.RequerySuggested += value; }
    remove { CommandManager.RequerySuggested -= value; }     
}

An event is raised whenever the CommandManager thinks that changes had happened and will affect the ability of commands to execute.

answered Jun 12, 2015 at 20:55

Olaru Mircea

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1 Comment

pquest Over a year ago

Sorry for the delay! This was the correct answer, I was pulled on to another project, and didn't get back to this till just now

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