Combobox binding in silverlight Ria Services

Question

I want to bind a combox with my entity model via domain services.

My entity model: COUNTRIES (ID, NAME) TABLE_TEST (PK_FIELD, FIELD2, COUNTRY_ID)

I created my entity model and the domain service.

My Xaml:

    <riaControls:DomainDataSource AutoLoad="True" d:DesignData="{d:DesignInstance my:COUNTRIES, CreateList=true}" Height="0" Name="COUNTRIESDomainDataSource" QueryName="GetCOUNTRIESQuery" Width="0">
        <riaControls:DomainDataSource.DomainContext>
            <my:DomainService1 />
        </riaControls:DomainDataSource.DomainContext>
    </riaControls:DomainDataSource>

    <riaControls:DomainDataSource AutoLoad="True" d:DesignData="{d:DesignInstance my:TABLE_TEST, CreateList=true}" Height="0" Name="TABLE_TESTDomainDataSource" QueryName="GetTABLE_TESTQuery" Width="0">
        <riaControls:DomainDataSource.DomainContext>
            <my:DomainService1 />
        </riaControls:DomainDataSource.DomainContext>
    </riaControls:DomainDataSource>

    <ComboBox Name="COUNTRIESComboBox"
              DataContext="{Binding ElementName=COUNTRIESDomainDataSource, Path=Data}" ItemsSource="{Binding}"
              DisplayMemberPath="ID"
              SelectedValuePath="NAME"
      SelectedValue="{Binding ElementName=TABLE_TESTDomainDataSource, Path=COUNTRY_ID}">
    </ComboBox>

The combobox is loaded with the correct values (all countries) but looks like it's not bounded with TABLE_TEST. When I change the register of TABLE_TEST, the value of the combo does not change.

What I am doing wrong? I looked many examples but no one is the same escenario, with domain data source and entity model.

I'm working with silverlight 5

Thanks

Answer 1

The DomainDataSource is an extremely bad fit as a datasource for Silverlight ComboBoxes. So far I've found Kyle McClennan's [MSFT] ComboBoxDataSource the most reliable in the use case you've described. In fact, he advised:

1) Do not use the DomainDataSource to populate ComboBoxes

You might think this is drastic or an over reaction, but I stick by the recommendation. Despite the simple samples you’ll see in other places, I think you’re better off avoiding the DDS when working with ComboBoxes. The DDS does not scale for more complex ComboBox scenarios.

In particular, you need to mark your combobox as being Async in the final attribute.

<ComboBox Name="COUNTRIESComboBox"
          DataContext="{Binding ElementName=COUNTRIESDomainDataSource, Path=Data}" ItemsSource="{Binding}"
          DisplayMemberPath="ID"
          SelectedValuePath="NAME"
          SelectedValue="{Binding ElementName=TABLE_TESTDomainDataSource, Path=COUNTRY_ID}"
          ex:ComboBox.Mode="Async">
</ComboBox>