CODEWITHSUNDEEP
wpfentity-frameworkdata-bindingcombobox
Larry R
Larry R

Reputation:

Binding WPF ComboBox to entity

Ok, Ive searched the heck out of the Interwebs and can't seem to find this right. I have a ComboBox that is bound to a CollectionViewSource of EntityFramework entities. The display is a template that shows the first/last name. The problem is, when an item is selected, the Display of the combobox == the object.ToString() (i.e. MyCompany.Data.Professional) instead of something useful.

I'm sure I'm missing a property here. The ri is the UserControl, and the SelectedPhysician is a DependencyProperty of the 

<ComboBox Grid.Column="1" Grid.Row="4"  x:Name="cmbReferringPhys"
      IsEditable="{Binding IsReadOnly}"
      ItemsSource="{Binding Source={StaticResource ProfessionalLookup}}"                                           
      SelectedItem="{Binding ElementName=ri, Path=SelectedPhysian, Mode=TwoWay, UpdateSourceTrigger=LostFocus, NotifyOnValidationError=True, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}"                                            
      HorizontalAlignment="Left" VerticalAlignment="Top" Height="19.277" Width="300" 
      IsSynchronizedWithCurrentItem="True"
      SelectionChanged="ReferringPhy_SelectionChanged" TabIndex="4">
 <ItemsControl.ItemTemplate>
   <DataTemplate>
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="100" />
                <ColumnDefinition Width="120" />                                
            </Grid.ColumnDefinitions>
            <TextBlock Text="{Binding FirstName}" Grid.Column="0"  Margin="4,0" />
            <TextBlock Text="{Binding LastName}"  Grid.Column="1" Margin="4,0"/>
        </Grid>                                                                   
    </DataTemplate>
</ItemsControl.ItemTemplate>

Upvotes: 0

Views: 3840

Answers (1)

oltman
oltman

Reputation: 1792

You can use a converter (tutorial), but that might be overdoing it a bit. I would recommend using the DisplayMemberPath property of the ComboBox.

To use a converter, you will need to create a converter class (one that implements IValueConverter.) Your code will look something like this:

public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
    MyCompany.Data.Professional prof = (MyCompany.Data.Professional)value;

    if (prof == null)
    {
        return string.Empty;
    }
    else
    {
        return string.Format("{0} {1}", prof.First, prof.Last); //or however you want to format this
    }  
}

// If you'll ever need to convert back from a string to a Professional,
// implement that logic here
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
    return null;
}

In the XAML, you'll do something like this:

<ComboBox>
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Converter={StaticResource [ConverterClassName]}}" /> 
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

Edit edit: In this case, I don't think you'll ever need to use ConvertBack, as you'll be able to get at the selected object by casting ComboBox.SelectedItem as a Professional.

Upvotes: 5

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