CODEWITHSUNDEEP
wpfxamldata-binding
Athafoud
Athafoud

Reputation: 3000

Bind Control Resource variable to DataContext

What I am trying to do is to create a variable in my (xaml) control resources and bind it to a property on my DataContext (e.g. ViewModel).

I am willing to have in my xaml, something like this

<system:Boolean x:Key="MyVariable" Value={Binding MyDataContextProperty}/>

I know that are more elegant ways to do it, e.g declare MyVariable to DataContext (e.g. ViewModel) and use it from there. However for testing reasons I want to explore the aforementioned aspect.

Is that even possible?

Upvotes: 0

Views: 266

Answers (1)

ASh
ASh

Reputation: 35646

A 'Binding' can only be set on a DependencyProperty of a DependencyObject.

so no, <system:Boolean x:Key="MyVariable" Value={Binding MyDataContextProperty}/> will not work

it is possible to declare a constant bool value in Resources

<StackPanel>
    <StackPanel.Resources>
        <system:Boolean x:Key="varBool">
            True
        </system:Boolean>
    </StackPanel.Resources>
    <CheckBox IsChecked="{StaticResource varBool}"/>
</StackPanel>

also possible to make a special DependencyObject

public class SomeObj: DependencyObject
{
    public static DependencyProperty ValueProperty = 
        DependencyProperty.Register("Value", typeof (bool), typeof (SomeObj), 
        new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));

    public bool Value
    {
        get { return (bool)GetValue(ValueProperty); }
        set { SetValue(ValueProperty, value); }
    }
}

bindings will work

<StackPanel>
    <StackPanel.Resources>
        <local:SomeObj x:Key="varBool1" Value="True"/>
        <local:SomeObj x:Key="varBool2" Value="{Binding Value, Source={StaticResource varBool1} }"/>
    </StackPanel.Resources>

    <CheckBox IsChecked="{Binding Value, Source={StaticResource varBool1}}"/>
    <CheckBox IsChecked="{Binding Value, Source={StaticResource varBool2}}"/>
</StackPanel>

the main question is why do all this if there is already MyDataContextProperty?

Upvotes: 1

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