This is a migrated thread and some comments may be shown as answers.

GridViewComboBoxColumn binding to Entity

8 Answers 317 Views

GridView

This is a migrated thread and some comments may be shown as answers.

Eric asked on 17 Oct 2014, 12:27 AM

I have a datagrid filled from an entity framework data model.

One of the columns is a combobox and I need to bind the SelectedValue of the combobox to the navigation property of the entity and I need to bind the SelectedIndex to the ID. If I can't bind to both of those properties and keep them consistent (ID matches the value in the database) then Entity Framework is a pain to work with.

It's not hard to do with a standard WPF combobox as explained here:

http://www.codeproject.com/Articles/301678/Step-by-Step-WPF-Data-Binding-with-Comboboxes

Here is the closes I've gotten:

<telerik:GridViewComboBoxColumn Header="Units"

                                                                                                                  ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}},Path=DataContext.UnitsOfMeasure}"                                                                                                                           DisplayMemberPath="Name"                                                                                                         DataMemberBinding="{Binding UnitOfMeasureID}"                                                                                     SelectedValueMemberPath="Id"/>

It Binds to the UnitsOfMeasure collection as the items source. It displays the name of the units as it should, and the UnitOfMeasureID in the datagrid row member is properly bound to the Id of the selected item from the combobox. The thing I can't seem to figure out is how to get the UnitOfMeasure object bound to the SelectedValue object of the combo box.

Thanks!

8 Answers, 1 is accepted

answered on 23 Oct 2014, 02:59 AM

Here is an example of a bound DataGridComboBoxColumn:

<DataGridComboBoxColumn Header="Units"
ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}},Path=DataContext.UnitsOfMeasure}"
DisplayMemberPath="Name"
SelectedItemBinding="{Binding Units}"
SelectedValueBinding="{Binding UnitsID}"
SelectedValuePath="Id"/>

Note that there are both a selectedItemBinding and a SelectedValueBinding. So, if I have a class made from entity framework and it is based off of a database table with a foreign key constraint to a "units" table, that class will have a "UnitsID" property and a "Units" property. The "UnitsID" property is just an integer while the "Units" Property is the "Units" instance where its "ID" matches "UnitsID" in the first class.

Those two properteis, "SelectedItemBinding" and "SelectedValueBinding" let me bind to both the ID and the Units item itself simultaneously which is very important when working with entity framework because if I change one but not the other then EntityFramework does not know which one I want and throws an exception when I try to save any changes to the class.

Here is the corresponding GridViewTemplateColumn:

<telerik:GridViewComboBoxColumn Header="Units"
ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}},Path=DataContext.UnitsOfMeasure}"
DisplayMemberPath="Name"
DataMemberBinding="{Binding UnitOfMeasureID}"
SelectedValueMemberPath="Id"/>

Note that it is one property short and so I cannot databind it to a class from entity framework properly.