Question

Based on a selected string value in the combobox I want to either show red/blue datatempalte inside the grid.

Can this be done without a ContentControl?

<UserControl.Resources >

<DataTemplate x:Key="red">
        <TextBox Text="red" />
    </DataTemplate>

    <DataTemplate x:Key="blue">
        <TextBox Text="blue" />
    </DataTemplate>

</UserControl.Resources>

<ComboBox ??? />
<Grid>
   // Show red or blue datatemplate here
</Grid>

Answer 1

Why not use a ContentControl?

To make this work simply i would put the templates in an array, which the ComboBox then can bind to:

<x:Array x:Key="templates" Type="{x:Type DataTemplate}">
    <DataTemplate>
        <DataTemplate.Resources>
            <sys:String x:Key="DisplayString">Red</sys:String>
        </DataTemplate.Resources>
        <TextBox Text="red" />
    </DataTemplate>

    <DataTemplate>
        <DataTemplate.Resources>
            <sys:String x:Key="DisplayString">Blue</sys:String>
        </DataTemplate.Resources>
        <TextBox Text="blue" />
    </DataTemplate>
</x:Array>

<ComboBox Name="combo" ItemsSource="{StaticResource templates}">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Resources[DisplayString]}" />
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>
<Grid>
    <ContentControl ContentTemplate="{Binding SelectedItem, ElementName=combo}" />
</Grid>