CODEWITHSUNDEEP
bindingdatatemplateuwpdesignerxbind
Martin Zikmund
Martin Zikmund

Reputation: 39092

x:Bind Design Time issues

I am trying to build my UWP app and currently am stuck with designer exceptions when trying to use DataTemplate with x:Bind in a Resource Dictionary.

I have created a Resource Dictionary "ItemTemplates.xaml" with a respective code-behind (to ensure x:Bind initialization). The file contains just one template:

<DataTemplate x:Key="HomeViewCategoryListItemTemplate" x:DataType="models:Category">
    <Button Background="#88333333" Height="110" VerticalContentAlignment="Top" Padding="10" HorizontalAlignment="Stretch">
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto" />
                <RowDefinition Height="Auto" />
            </Grid.RowDefinitions>
            <TextBlock FontWeight="Light" HorizontalAlignment="Center" Text="{x:Bind Name}" FontSize="{ThemeResource TextStyleExtraLargeFontSize}" />
            <TextBlock Foreground="{ThemeResource ToolTipForegroundThemeBrush}" HorizontalAlignment="Center" Margin="0,10,0,0" Text="{x:Bind Description}" Grid.Row="1" TextAlignment="Center" TextWrapping="Wrap" />
        </Grid>
    </Button>
</DataTemplate>

Then I added this resource dictionary to App.xaml like this:

<Application.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="ms-appx:///Resources/Core.xaml" />
            <resources:ItemTemplates />
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</Application.Resources>

Now the project is unusable, because designer throws weird exceptions, but when I Clean and Rebuild the project and navigate to the HomeView.xaml page, the designer shows just the default "ToString()" items (basically the list view contains just three times the text "Models.Categories") in the ListView and the ItemTemplate property of my ListView is underlined and shows the following error:

The resource "HomeViewCategoryListItemTemplate" could not be resolved.

When I navigate back to App.xaml, I see yet another underline there (of the <resources:ItemTemplates /> line) which says:

The property 'DataType' was not found in type 'DataTemplate'.

Both errors are non-sensical, because when I actually run the app, there are no issues and everything works perfectly. The only workaround I have found so far is to include the ResourceDictionary two times in both the classic way and the "compiled" way:

<ResourceDictionary Source="ItemTemplates.xaml" />
<resoures:ItemTemplates />

This solution works and then everything works both in design time and in run-time, but I really think it is quite messy and there has to be a better, safer approach or I am missing something trivial.

I am running Visual Studio 2015 Update 1 and have the newest UWP SDK installed. The project targets build 10240.

Edit: Another exception that the designer very often throws and crashes completely:

 Unable to cast object of type 'System.String' to type 'Models.Data.Categories.Category'.

According to the StackTrace output this happens inside the ItemTemplates.xaml.cs code - specifically the generated method ProcessBindings. Again, the project still compiles and runs normally, but the designer does not even bother trying to show the output.

Upvotes: 5

Views: 808

Answers (1)

Hunter Tran
Hunter Tran

Reputation: 15345

For this current version, prefer Binding over x:Bind

an answer from a Microsoft engineers

I've got the same problems as you did, plus a ton of bugs when using x:Bind in Design time. Quickest way to fix: use Binding as old time. And when you release, if performance is under consideration, change the Binding to x:Bind

Upvotes: 0

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