Question

Using WPF, XAML, VS2008, and Blend 2 (or 3 Beta preferred), what is your process for creating data templates? Do you have a process for testing the data template’s appearance WITHOUT spinning up your app just to test how the data looks? Is there a process I can use in Blend to make developing data templates more graphical?

Answer 1

You can specify data at design-time through Blend, or (to get it working in VS as well) do this:

• Create a subclass of the object that you set as your DataContext.
• In the constructor of this subclass, set the properties to some test values.
• Declare an instance of the subclass as a resource.
• Set the DataContext to this resource.
• Remember to clear or set the DataContext to something sensible at runtime, otherwise users will see your design-time data.

Works in Silverlight as well.

Here’s some example code:

// The object (in a list) that'll be bound as our ListBox ItemsSource
public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

// Our design-time data. Note that we add list items in the constructor
public class PersonDesignTimeData : ObservableCollection<Person>
{
    public PersonDesignTimeData()
    {
        this.Add(new Person { FirstName = "Fred", LastName = "Smith" });
        this.Add(new Person { FirstName = "Jim", LastName = "Brown" });
        this.Add(new Person { FirstName = "Dave", LastName = "Jones" });
    }
}

Window1.xaml:

<Window x:Class="DesignTimeDataDemo.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:DesignTimeDataDemo"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <local:PersonDesignTimeData x:Key="PersonDesignTimeData"/>
    </Window.Resources>
    <Grid x:Name="root" DataContext="{StaticResource PersonDesignTimeData}">
        <ListBox
            ItemsSource="{Binding}"
            >
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid Width="200">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*"/>
                            <ColumnDefinition Width="2*"/>
                        </Grid.ColumnDefinitions>
                        <TextBlock Grid.Column="0" Text="{Binding FirstName}"/>
                        <TextBlock Grid.Column="1" Text="{Binding LastName}"/>
                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

    </Grid>
</Window>