In XAML is it possible to use an ElementName binding before the element it refers to is declared?

Question

I have a UserControl with some InputBindings. I wanted to make one of the input bindings (arrow key press) execute a command on a GUI control in my UserControl . So

e.g.

<UserControl.InputBindings>
    <KeyBinding Key="Up" Command="{Binding ElementName=MyViewElement, Path=MoveUpCommand}"/>
    <KeyBinding Key="Down" Command="{Binding ElementName=MyViewElement, Path=MoveDownCommand}"/>
</UserControl.InputBindings>

But, this fails because MyViewElement is not found because I assume it is declared later in the XAML. If I move my InputBindings to the end of the XAML file everything works as intended.

I kinda prefer my InputBindings to be at the top, is it possible to make it ignore the declaration order?

No I don't think you can. You can check this: http://stackoverflow.com/questions/1301119/silverlight-xaml-attribute-definition-order-matters — mlemay, Mar 01 '13 at 19:45
think of your Xaml like a code block, you cant use variables before they are declared. — sa_ddam213, Mar 01 '13 at 23:52
@sa_ddam213 Yeah, I was hoping to think of it like a class, where I can use them regardless of where they are declared ;-) — Alan, Mar 02 '13 at 06:38

score 1 · Accepted Answer · answered Mar 02 '13 at 07:21

1

@Stewbob What are you talking about?

Take a look at this: http://msdn.microsoft.com/en-us/library/ms752308.aspx

<Window.CommandBindings>
  <CommandBinding Command="ApplicationCommands.Open"
                  Executed="OpenCmdExecuted"
                  CanExecute="OpenCmdCanExecute"/>
</Window.CommandBindings>

According to what you said this should never work properly but it does:

<StackPanel>
  <Menu>
    <MenuItem Command="ApplicationCommands.Paste"
              CommandTarget="{Binding ElementName=mainTextBox}" />
  </Menu>
  <TextBox Name="mainTextBox"/>
</StackPanel>

From what you said the binding comes first also it will be executed first and therefore the binding to mainTextBox should never work. Thats very not true.

answered Mar 02 '13 at 07:21

snowy hedgehog

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I'll give it a second look – Alan Mar 02 '13 at 08:28
My test code at home is working now, but I'm sure I received an error before... bizarre.. I will check with the same code as before on Monday and get back to you – Alan Mar 02 '13 at 10:21
Alright, you're right. I have no idea why I was getting a binding error before, but I am receiving no such error and it is working fine. Thank you for being insistent! – Alan Mar 04 '13 at 15:12

score 0 · Answer 2 · answered Mar 01 '13 at 21:12

0

Sure you can do everything in XAML, including such Binding at Window level. Show more code of your XAML/MyViewElement. Maybe we could tell you how to do it without errors. Also post your error here please.

answered Mar 01 '13 at 21:12

snowy hedgehog

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score 0 · Answer 3 · answered Nov 23 '17 at 10:29

But, this fails because MyViewElement is not found because I assume it is declared later in the XAML.

To avoid that, you can use the following in the code behind instead of the constructor:

protected override void OnInitialized(EventArgs e)
{
    SomeCommand = new DelegateCommand(SomeExecuteMethod);

    InitializeComponent();
    base.OnInitialized(e);
}

This ensures the commands are already instantiated before you use them with:

Command="{Binding ElementName=MyUserCOntrol, Path=SomeCommand}"

In XAML is it possible to use an ElementName binding before the element it refers to is declared?

3 Answers3