Question

I’m trying to set seletected value to a pre-loaded combobox using silverlight with MVVM.

I load these combobox items before selecting value.

For example I have a combobox to select a country. My first step is to load a List which is bound to the combobox source. This is loading perfectly.

After this, I have a “SelectedCountry” object bound to the selectedItem of the combobox in a two-way binding.

This is working perfect when I select any of the combobox values and my SelectedCountry object is correctly selected.

The problem comes when I try to assign the selected value in my ViewModel. This way, the combobox selecteditem is not updated.

I suppose this is because, on fact, they are not the same object (they have the same values but they are diferent references).

Should this work if I re-implement the equals method? Or should I find the same object by searching into the List?? This would be very easy because this two countries would be the same if they have the same id… but I can have more complex objects and I think the equals method would be better.

Thanks in advance!!

Edit for adding some code example:

<ComboBox Grid.Column="7" Margin="6,0" Name="cBTipoPoliza" VerticalAlignment="Center" TabIndex="4" ItemsSource="{Binding TiposPolizas, Mode=OneWay}" SelectedItem="{Binding TipoPoliza,  Mode=TwoWay}">
 <ComboBox.ItemTemplate>
       <DataTemplate>
            <TextBlock Text="{Binding nombre_tipo}" />
       </DataTemplate>
 </ComboBox.ItemTemplate>

Answer 1

Usually I just override the .Equals() method to check if they are equal by ID or Name