Silverlight Binding with multiple collections
- by George Evjen
We're designing some sport specific applications. In one of our views we have a gridview that is bound to an observable collection of Teams. This is pretty straight forward in terms of getting Teams bound to the GridView. <telerik:RadGridView Grid.Row="0" Grid.Column="0" x:Name="UsersGrid" ItemsSource="{Binding TeamResults}" SelectedItem="{Binding SelectedTeam, Mode=TwoWay}"> <telerik:RadGridView.Columns> <telerik:GridViewDataColumn Header="Name/Group" DataMemberBinding="{Binding TeamName}" MinWidth="150"></telerik:GridViewDataColumn> </telerik:RadGridView.Columns> </telerik:RadGridView> We use the observable collection of teams as our items source and then bind the property of TeamName to the first column. You can set the binding to mode=TwoWay, we use a dialog where we edit the selected item, so our binding here is not set to two way. The issue comes when we want to bind to a property that has another collection in it. To continue on our code from above, we have an observable collection of teams, within that collection we have a collection of KeyPeople. We get this collection using RIA Serivces with the code below. return _TeamsRepository.All().Include("KeyPerson");
Here we are getting all the teams and also including the KeyPerson entity. So when we are done with our Load we will end up with an observable collection of Teams with a navigation property / entity of KeyPerson. Within this KeyPerson entity is a list of people associated with that particular team. We want to display the head coach from this list of KeyPersons. This list currently has a list of ten or more people that are bound to this team, but we just want to display the Head Coach in the column next to team name.
The issue becomes how do we bind to this included entity? I have found about three different ways to solve this issue. The way that seemed to fit us best is to utilize the features within RIA Services. We can create client side properties that will do the work for us. We will create in the client side library a partial class of Team. We will end up in our library a file that is Team.shared.cs. The code below is what we will put into our partial team class.
public KeyPerson Coach { get { if (this.KeyPerson != null && this.KeyPerson.Any()) {
return this.KeyPerson.Where(x => x.RelationshipType == “HeadCoach”).FirstOrDefault();
} return null; } }
We will return just the person that is the Head Coach and then be able to bind that and any other additional properties that we need.
<telerik:GridViewDataColumn Header="Coach" DataMemberBinding="{Binding Coach.Name}" MinWidth="150"></telerik:GridViewDataColumn>
There are other ways that we could have solved this issue but we felt that creating a partial class through RIA Services best suited our needs.
