CODEWITHSUNDEEP
c#wpfxamltemplatescontentpresenter
MisterPresident
MisterPresident

Reputation: 561

Stange behavior of ContentPresenter

I was just playing around with a simple ContentPresenter.

<TextBox Text="{Binding Path=TestString, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"/>
<ContentPresenter Content="{Binding}">
    <ContentPresenter.ContentTemplate>
        <DataTemplate>
            <StackPanel>
                <TextBox Text="{Binding Path=TestString, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"/>
            </StackPanel>
        </DataTemplate>
        </ContentPresenter.ContentTemplate>
</ContentPresenter>

This code works perfectly - if I enter something to the Stackpanel Textbox the Textbox outside gets actualiced. The other way round works too.

If I change the code to:

<TextBox Text="{Binding Path=TestString, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"/>
<ContentPresenter Content="{Binding Path=TestString, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}">
    <ContentPresenter.ContentTemplate>
        <DataTemplate>
            <StackPanel>
                <TextBox Text="{Binding Path=., UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"/>
            </StackPanel>
        </DataTemplate>
    </ContentPresenter.ContentTemplate>
</ContentPresenter>

When I change the Textbox outside of the ContentPresenter it gets actualiced BUT if I change the Text inside the Template it does not get converted back.

Why?

Thank you!

Upvotes: 1

Views: 639

Answers (1)

eran otzap
eran otzap

Reputation: 12533

 <ContentPresenter Content="{Binding Path=TestString,UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}">
      <ContentPresenter.ContentTemplate>
         <DataTemplate>
            <StackPanel>
               <TextBox Text="{Binding Path=., UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"/>
            </StackPanel>
        </DataTemplate>
     </ContentPresenter.ContentTemplate>
 </ContentPresenter>

Binding to Path=. means Binding to the DataContext object. Inside of a ContentTemplate the DataContext is the Content. i.e. your DataContext is a String. in this case the String received from the Binding to TestString.

use snoop to observe this.

Edit :

is this what you are looking for 

 <TextBox Text="{Binding Path=Content,RelativeSource={RelativeSource AncestorType=ContentPresenter}}"/>

BTW: ContentPresenter by itself inside a control template does all this for you by default.

Upvotes: 1

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