How to bind itemsource property to ID

Question

I have one object DataSet which has a name property and a ID property. I have a list of datasets in my viewmodel, which should be the itemsource of a DataGrid Combobox column. I have defined the binding as follows:

dataGridControl:DataGridComboBoxColumn
                                Binding="{Binding DataSetIndex}"
                                Header="DataSet"
                                ItemsSource="{x:Bind Model.DataSets}"
                                DisplayMemberPath="Name"
                                Tag="DataSet" />

Now, this works, except for the fact that I somehow need to tell the binding that it should use the DataSet.ID property. So when a user selects a value in the combobox, the binding DataSetIndex should be set to a int, which is the DataSet.ID property. How can I do that in the binding? Right now I of course get an error saying that the itemsource does not have a int property, cause it tries to use the DataSet object as a whole. Now, is there no SelectedValuePath in the community toolkit? Do I have to use a templatecolumn?

Here is my updated question based on your solution. It also has the codebehind binding.

 <dataGridControl:DataGridTemplateColumn Header="DataSet">
<dataGridControl:DataGridTemplateColumn.CellEditingTemplate>
    <DataTemplate x:DataType="local:DataExtractionSetupViewModel">
        <ComboBox x:Name="dataSetsComboBox" Loaded="ComboBox_Loaded"
                  DisplayMemberPath="Name"
                  SelectedValue="{Binding DataSetIndex, Mode=TwoWay}" SelectedValuePath="ID" IsDropDownOpen="True"/>
    </DataTemplate>
</dataGridControl:DataGridTemplateColumn.CellEditingTemplate>
<dataGridControl:DataGridTemplateColumn.CellTemplate>
    <DataTemplate> 
    <TextBlock Text="{Binding DatasetIndex}"/>
</DataTemplate>
</dataGridControl:DataGridTemplateColumn.CellTemplate>
</dataGridControl:DataGridTemplateColumn>

Now my only question is, how can we make this custom template column look exactly like a normal datagrid combobox column, and also show the datasets name in the textbox instead of the index?

if the solution is to create a custom template column, I have 2 questions. #1 how can I refer to Model.DataSets when the Model is defined and newed in the code behind when using DataTemplate in the custom column? #2 how can one make a custom templatecolumn with a combobox behave the same as the original DataGrid Combobox column? — miniHessel
– miniHessel, Commented Jan 6 at 17:19

Andrew KeepCoding · Accepted Answer · 2025-01-07 09:05:35Z

1

The following is using code-behind but works:

<toolkit:DataGridTemplateColumn>
    <toolkit:DataGridTemplateColumn.CellTemplate>
        <DataTemplate x:DataType="local:DataSet">
            <ComboBox
                DisplayMemberPath="Name"
                Loaded="ComboBox_Loaded"
                SelectedIndex="{x:Bind DataSetIndex, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
        </DataTemplate>
    </toolkit:DataGridTemplateColumn.CellTemplate>
</toolkit:DataGridTemplateColumn>

private void ComboBox_Loaded(object sender, RoutedEventArgs e)
{
    if (sender is not ComboBox comboBox)
    {
        return;
    }

    comboBox.SetBinding(
        ComboBox.ItemsSourceProperty,
        new Binding()
        {
            Source = Model,
            Path = new PropertyPath("DataSets"),
        });
}

If you want to change how the ComboBox looks, try setting:

CornerRadius to 0
BorderThickness to 0
Background to Transparent

edited Jan 7 at 9:05

answered Jan 7 at 0:42

Andrew KeepCoding

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10 Comments

miniHessel Jan 7 at 7:27

Thank you for the reply. For the cell to look exactly like a normal datagrid combobox column, shouldn't it have a editing template and then a non editing template with a textbox?

miniHessel Jan 7 at 7:32

also, it seems like the binding is missing something. DataSetIndex is in the ViewModel.Documents observablecollection this datagrid is made from, and DataSets is a observablecollection in the ViewModel. Also it doesn't have to be in code behind, I just said that the viewmodel is defined in codebehind.

miniHessel Jan 7 at 8:01

Ok, so I tesdted your suggestions. Binding in codebehind defeintely solves the issue of the binding not working when doing exactly the same in XAML. I guess it just isn't possible in XAML due to a timing issue? I have tried both x:bind and binding.

Andrew KeepCoding Jan 7 at 8:24

AFAIK, this is the only way that works now.

miniHessel Jan 7 at 8:26

Ok, it works great now. The only issue is how I can make the textbox show the value. See my updated question for the code. I guess one approach could be to bind to the combobox selected value or something?

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