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Using ViewModels and DataTemplates to compose your UI

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Several drops ago we introduced a ViewModel composition spike. The purpose of this spike was to introduce a different way to compose your UI that WPF offers. That is instead of having your views and regions be UI-Elements, having them as pure models. What I mean by this is instead of having a Employee Region which is a tab, that contains EmployeeViews, you have a model (the region) that contains Employees. Likewise instead of of having a panel that displays a CustomerView, you have a  model that contains a single Customer. So how do I get my Employee region to display as a Tab, and my Employee to display itself in the same way as the EmployeeView? The answer is using DataTemplates. Using DataTemplates, you can define the UI rendering for a specific type (in this case the Employee and the EmployeeRegion). The nice thing for the no code-behind zealots among us is that there is absolutely NO CODE BEHIND in a DataTemplate.

Below you can see an example of what an Employee template might look like:

 <DataTemplate DataType="{x:Type Employee}">

     <Grid x:Name="GeneralGrid">

         <Grid.ColumnDefinitions>

             <ColumnDefinition></ColumnDefinition>

             <ColumnDefinition Width="5"></ColumnDefinition>

             <ColumnDefinition Width="*"></ColumnDefinition>

         </Grid.ColumnDefinitions>

         <Grid.RowDefinitions>

             <RowDefinition></RowDefinition>

             <RowDefinition></RowDefinition>

             <RowDefinition></RowDefinition>

             <RowDefinition></RowDefinition>

         </Grid.RowDefinitions>

         <TextBlock Text="First Name:" Grid.Column="0" Grid.Row="0"></TextBlock>

         <TextBlock Text="Last Name:" Grid.Column="2" Grid.Row="0"></TextBlock>

         <TextBlock Text="Phone:" Grid.Column="0" Grid.Row="2"></TextBlock>

         <TextBlock Text="Email:" Grid.Column="2" Grid.Row="2"></TextBlock>

  

         <TextBox x:Name="FirstNameTextBox" Text="{Binding Path=FirstName}"

             Grid.Column="0" Grid.Row="1"></TextBox>

         <TextBox x:Name="LastNameTextBox" Text="{Binding Path=LastName}" 

             Grid.Column="2" Grid.Row="1"></TextBox>

         <TextBox x:Name="PhoneTextBox" Text="{Binding Path=Phone}" 

             Grid.Column="0" Grid.Row="3"></TextBox>

         <TextBox x:Name="EmailTextBox" Text="{Binding Path=Email}" Grid.Column="2" 

             Grid.Row="3"></TextBox>

     </Grid>

 </DataTemplate>

Julian has a set of posts where he is discussing this interesting approach to composition. He's done two posts so far, but I am sure there's much more to come.

Using the Presentation Model in WPF

First approach to Presentation Model with DataTemplates

Great stuff!

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