Is it possible to create a template for a GridViewColumn, without fixed data binding?

Question

Is this possible?

I have a ListView and I want to create a template for the columns, so that each column that I mark as a 'cellTextBox' displays with a textbox in it (and also calls the TextBox_LostFocus() on the LostFocus event). I'd really like to use a single template rather than defining a DockPanel and TextBox for every single column. However, each column is going to be bound to a different column in the data source.

In other words, I'd like a "cookie cutter" for GridViewColumns that allows me to specify a different binding path for each one.

I tried something like this (among other things), but it doesn't work.

Any ideas?

<Page.Resources>
            <DataTemplate x:Key="cellTextBox">
                <DockPanel>
                <TextBox
                        LostFocus="TextBox_LostFocus"
                        Width="100"
                        Text="{Binding RelativeSource={RelativeSource Mode=TemplatedParent},Path=DisplayMemberBinding}"
                />
                </DockPanel>
            </DataTemplate>
</Page.Resources>
<StackPanel>

        <ListView ScrollViewer.HorizontalScrollBarVisibility="Disabled" 
                  HorizontalAlignment="Stretch" 
                  ItemsSource="{Binding Tables[0]}" 
                  Width="Auto"
                  x:Name="Service_Tasks">

            <ListView.View>
                <GridView>
                    <GridViewColumn Width="120" CellTemplate="{StaticResource cellTextBox}" DisplayMemberBinding={Binding Path=Field1} Header="Field1" />
                    <GridViewColumn Width="120" CellTemplate="{StaticResource cellTextBox}" DisplayMemberBinding={Binding Path=Field2} Header="Field2" />
                    <GridViewColumn Width="120" CellTemplate="{StaticResource cellTextBox}" DisplayMemberBinding={Binding Path=Field3} Header="Field3" />
                    <GridViewColumn Width="120" CellTemplate="{StaticResource cellTextBox}" DisplayMemberBinding={Binding Path=FieldN} Header="FieldN" />
                    <!-- ... other columns ... -->
                </GridView>
            </ListView.View>

        </ListView>
</StackPanel>

EDIT - I thought I would share the Visual Basic translation of @H.B.'s solution, which worked for me. Perhaps this will help out someone else.

Imports System.Windows.Markup

Public Class TemplateBuilderExtension : Inherits StaticExtension
    Dim _path As String
    Shared _tagpath As String

    'Private TagPath As String

    Shared Property TagPath As String
        Get
            TagPath = _tagpath
        End Get
        Private Set(ByVal value As String)
            _tagpath = value
        End Set
    End Property

    Property Path As String
        Get
            Path = _path
        End Get
        Set(ByVal value As String)
            _path = value
        End Set
    End Property

    Public Overrides Function ProvideValue(ByVal serviceProvider As System.IServiceProvider) As Object
        TagPath = Path
        Dim resourceExt = New StaticResourceExtension("TemplateBuilder_BaseTemplate")
        'Dim baseTemplate As DataTemplate = DirectCast(resourceExt.ProvideValue(serviceProvider), DataTemplate)
        ProvideValue = DirectCast(resourceExt.ProvideValue(serviceProvider), DataTemplate)
    End Function

    Public Sub New()
        MyBase.new()
    End Sub

    Public Sub New(ByVal Path As String)
        Me.Path = Path
    End Sub
End Class

Public Class TemplateBuilderTagExtension : Inherits MarkupExtension
    Public Sub New()
        MyBase.New()
    End Sub
    Public Overrides Function ProvideValue(ByVal serviceProvider As System.IServiceProvider) As Object
        ProvideValue = New Binding(TemplateBuilderExtension.TagPath)
    End Function
End Class

Obviously, the XAML is the same, regardless.

Do not forget to add the following namespace reference to your root-level tag:

xmlns:me="clr-namespace:WpfApplication1", replacing WpfApplication with whatever your application's root namespace is (this can be found in your application's properties).

Thanks again @H.B.!

Disbelieve

Answer 1

The only method i can think of right now to inline this is using markup-extensions as you try to pass more than one value to one property.

Getting variable data into the template seems to be non-trivial though and the following approach using a static property is quite the hack, maybe you can think of something better:

<ListView ItemsSource="{Binding Data}">
    <ListView.Resources>
        <!-- x:Shared="False" because otherwise the Tag extension is only evaluated the first time the resource is accessed -->
        <DataTemplate x:Shared="false" x:Key="TemplateBuilder_BaseTemplate">
            <TextBox Text="{me:TemplateBuilderTag}" Width="100" LostFocus="TextBox_LostFocus" />
        </DataTemplate>
    </ListView.Resources>
    <ListView.View>
        <GridView>
            <GridViewColumn CellTemplate="{me:TemplateBuilder Name}"  />
            <GridViewColumn CellTemplate="{me:TemplateBuilder Occupation}" />
        </GridView>
    </ListView.View>
</ListView>

public class TemplateBuilderExtension : MarkupExtension
{
    public string Path { get; set; }

    public TemplateBuilderExtension() { }
    public TemplateBuilderExtension(string path)
    {
        Path = path;
    }

    // Here be dirty hack.
    internal static string TagPath { get; private set; }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        TagPath = Path;
        var resourceExt = new StaticResourceExtension("TemplateBuilder_BaseTemplate");
        // This line causes the evaluation of the Tag as the resource is loaded.
        var baseTemplate = resourceExt.ProvideValue(serviceProvider) as DataTemplate;
        return baseTemplate;
    }
}

public class TemplateBuilderTagExtension : MarkupExtension
{
    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return new Binding(TemplateBuilderExtension.TagPath);
    }
}

I tried to use a custom service provider when getting the resource but unfortunately it did not arrive in ProvideValue of the tag, that would have been a better way to get the path accross.

You could of course create the template dynamically from scratch in the TemplateBuilderExtension, that way you will not run into such issues.

Katydid

+1 this looks really promising. I will try it this evening since I dont have my code with me at the moment. I'm a little surprised that XAML offers ways to template controls, but not elements like GridViewColumn which are not Visual elements but seem like they would be used frequently. Am I missing something obvious? Should I be using something besides a ListView for these types of lists (keeping in mind that this project is in 3.5)? – Disbelieve

@transistor1: Well, the ListView is a view, it probably is not meant for editing, you could use the DataGrid from the WPF Toolkit instead. – Katydid

Quick question: does the line public string Path { get; set; } mean that the Path property is not stored internally (i.e. get and set are not implemented)? Or is it a default property implementation? I'm more accustomed to VB, though I've done some rudimentary C# coding, so I'm translating it. – Disbelieve

... pretty sure it is a default property implementation. – Disbelieve

@transistor1: That's called auto-implemented property, just shorthand for a private backing field and a public property which exposes it. Of course the field cannot be accessed directly that way... – Katydid