Chris Roeder Chris Roeder - 1 year ago 154
C# Question

WPF- Combobox Binding

I have a class named "employee":

public string Forname { get; set; }
public string Lastname { get; set; }
public EmployeeGroup Group { get; set; }

a class "EmployeeGroup":

public string Groupname { get; set; }
public short GroupID { get; set; }

and a wpf:

<ComboBox x:Name="cmbGroup" SelectedItem="{Binding Group}" HorizontalAlignment="Left" Margin="342,226,0,0" VerticalAlignment="Top" Width="129"/>
<TextBox x:Name="txtForename" Text="{Binding Forname}" HorizontalAlignment="Left" Height="24" Margin="342,21,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="129" VerticalContentAlignment="Center" GotFocus="SelectText"/>
<TextBox x:Name="txtLastname" Text="{Binding Lastname}" HorizontalAlignment="Left" Height="24" Margin="342,47,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="129" VerticalContentAlignment="Center" GotFocus="SelectText"/>
<ListBox x:Name="lstEmployee" HorizontalAlignment="Left" Height="362" Margin="25,19,0,0" VerticalAlignment="Top" Width="217" SelectionChanged="lstEmployee_SelectionChanged"/>

The ComboBox and the ListBox gets the source from the code-behind-file (a ObservableCollection):

cmbGroup.ItemsSource = Database_Contract.GetListOfContract();
lstEmployee.ItemsSource = Database_Employee.GetListOfEmployee();

And I set the DataContext when an employee is selected in the ListBox in the code-behind-file of the wpf:

DataContext = lstEmployee.SelectedItem;

The binding with the ListBox and TextBoxes works fine, but I have a problem with the Combobox:
The source works, means that i can select different Groups. But there is no binding to the selected employee. So when I select the employee, the TextBoxes with the fore- and lastname filled right, but the Combobox ist emtpy. But when I click the Combobox, then I can choose from the given Groups.

So what I've done wrong?

When I set the Binding of the ComboBox.SelectedIndex to the Group.GroupID, then it works. But it's not guaranteed that the GroupID and the ComboBox-Index is the same.

Answer Source

I found a solution... I've changed to MVVM, set the binding of the cmbGroup to the ListOfGroup, overridden the GetHashCode and Equals methods of the class EmployeeGroup, and it works. Thanks guys!

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