Question

I have a wpf application using caliburn.micro.
It has a datagrid and a combobox.

Here is the DataGrid:

<DataGrid x:Name="TriageMapRecords"
          Grid.Row="0" Grid.ColumnSpan="5"
          AutoGenerateColumns="False"
          BaseControls:DataGridExtension.Columns="{Binding TriageMapRecordColumns}"
          CanUserAddRows="False" IsReadOnly="True"
          SelectedItem="{Binding Path=SelectedTriageMapRecord, Mode=TwoWay}">

SelectedTriageMapRecord object contains a field CounterpartyNameId.

I want to bind selected value in the combobox to CounterpartyNameId of the SelectedTriageMapRecord.

I tried this:

<ComboBox x:Name="RefCounterparties" 
          DisplayMemberPath="Name" SelectedValuePath="Id" 
          SelectedValue="{Binding Source=SelectedTriageMapRecord, 
                                  Path=CounterpartyNameId, Mode=TwoWay}"
          Grid.Row="1" Grid.Column="1" HorizontalAlignment="Left" 
          Width="Auto" MinWidth="100" Margin="3,3,0,3"/>

But this didn’t work. Could you tell me what I am missing?

Answer 1

It looks like you probably want to do it like this:

<ComboBox x:Name="RefCounterparties"  
          DisplayMemberPath="Name" SelectedValuePath="Id"  
          SelectedValue="{Binding SelectedTriageMapRecord.CounterpartyNameId,  
                                  Mode=TwoWay}" 
          Grid.Row="1" Grid.Column="1" HorizontalAlignment="Left"  
          Width="Auto" MinWidth="100" Margin="3,3,0,3"/> 

You don’t want to set a source because your source is still the DataContext. Then you specify the path on the DataContext to drill down into. In this case, the SelectedTriageMapRecord property of the DataContext, and then the CounterpartyNameId property of the SelectedTriageMapRecord object.