The tag 'DataTrigger' does not exist in XML namespace?

Question

I am getting a really annoying error

Error 175 The tag 'DataTrigger' does not exist in XML namespace 'http://schemas.microsoft.com/winfx/2006/xaml/presentation'.

I am using Visual Studio 2010 with Silverlight 5. As far as I can tell the references are ok but obviously not, can someone tell me what is causing this please

I believe this may resolve the other question I raised earlier but cant test it because of this error

Change DataTemplate to use depending on condition

xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"             
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:iv="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" 
xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions"
xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"  

mc:Ignorable="d"    
>
<UserControl.Resources>
  <DataTemplate x:Key="SelectControl">
    <ContentControl Content="{Binding}">
        <ContentControl.Style>
            <Style TargetType="ContentControl">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding BlockType}" Value="Locked">
                        <Setter Property="DataTemplate"
                                Value="{StaticResource LockedClip}" />
                    </DataTrigger>
                    <DataTrigger Binding="{Binding BlockType}" Value="Unlocked">
                        <Setter Property="DataTemplate"
                                Value="{StaticResource UnlockedClip}" />
                    </DataTrigger>
                    <DataTrigger Binding="{Binding BlockType}" Value="Unlock">
                        <Setter Property="DataTemplate"
                                Value="{StaticResource UnlockClip}" />
                    </DataTrigger>                      
                </Style.Triggers>
            </Style>
        </ContentControl.Style>
    </ContentControl>
</DataTemplate>

<DataTemplate x:Key="LockedClip">
  <my:SingleLockedFlexBlock Height="117"/>            
</DataTemplate>    

<DataTemplate x:Key="UnlockedClip">
  <my:SingleLockedFlexBlock Height="50"/>            
</DataTemplate>    

 <DataTemplate x:Key="UnlockClip">
   <my:SingleLockedFlexBlock Height="200"/>            
 </DataTemplate>

Hope someone can shed light on this?

Paul

Community · Accepted Answer · 2017-05-23 11:59:55Z

2

DataTrigger is not supported by default in Silverlight, but you could use the SDK from the Blend Preview for SL5 to obtain corresponding behavior.

You might want to take a look at:

Expression SDK in Silverlight–DataTrigger Example blog post
Data Triggers in Silverlight blog post
the SO question What is the replacement for DataTrigger in Silverlight.

XAML code wise, I believe you need to change the following:

<Style.Triggers>
    <DataTrigger Binding="{Binding BlockType}" Value="Locked">
        <Setter Property="DataTemplate"
            Value="{StaticResource LockedClip}" />
    </DataTrigger>
    ...

into the following:

<iv:Interaction.Triggers>
    <ei:DataTrigger Binding="{Binding BlockType}" Value="Locked">
        <ei:ChangePropertyAction PropertyName="DataTemplate"
            Value="{StaticResource LockedClip}" />
    </ei:DataTrigger>
    ...

edited May 23, 2017 at 11:59

CommunityBot

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answered Aug 19, 2012 at 8:16

Anders Gustafsson

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3 Comments

Paul Over a year ago

Thanks I got passed the compile errors but still cant get this to work. There is a comment saying add at the same level as Visual State for the control but I have no idea what level that is?

Anders Gustafsson Over a year ago

@Paul I have had some problems getting the trigger to activate myself, but I have at least updated my answer with some code that should hopefully be of help.

Paul Over a year ago

Thanks Anders I will try this when I get back to the office :)

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