RadGridview - Hierarchical: What event is fired when expanding a selected row?

[Top Gun]

I have a hierarchical telerik gridview in Silverlight.  On the left most column, I have the expand button “+ sign.”  When I click on the expand button “+ sign”, the row expands and I can view more details for my selection.   

What event is fired when I click the expand button “+ sign”?  I want to retrieve data from the database when the user chooses to expand a particular row.  I need to do this in the correct event handler and none of the event handlers seem to work.

[Yordanka]

Hello Top Gun,

You can use RowIsExpandedChanging event. Also, you may take a look at this blog post.

Let us know if you need further help.
 
Best wishes,
Yordanka
the Telerik team

[Top Gun]

RowIsExpandedChanging event was not fired when I selected the expand button "+ sign" on the grid. 
My code works.  I just need the event that fires when I click on the expand button "+ sign."
Here is my Xaml.

<Controls:RadGridView x:Name="PeopleGrid"  Margin="0"
                            RowIndicatorVisibility="Collapsed" IsReadOnly="True"
                            Width="748" MinHeight="386" MaxHeight="500"
                            AutoGenerateColumns="False"
                            VerticalAlignment="Top"
                            VerticalContentAlignment="Stretch"
                            HorizontalContentAlignment="Stretch"
                            HorizontalAlignment="Stretch"
                            RowIsExpandedChanging="PeopleGrid_RowIsExpandedChanging"
                            >
           <Controls:RadGridView.Columns>
               <Controls:GridViewToggleRowDetailsColumn />
               <Controls:GridViewDataColumn Header="ID" DataMemberBinding="{Binding ID}" />
               <Controls:GridViewDataColumn Header="First Name" DataMemberBinding="{Binding FirstName}" />
               <Controls:GridViewDataColumn Header="Last Name" DataMemberBinding="{Binding LastName}" />
           </Controls:RadGridView.Columns>
           <telerik:RadGridView.RowDetailsTemplate>
               <DataTemplate>
                   <ItemsControl Name="ICClasses" ItemsSource="{Binding Path=ClassList, Mode=OneWay}">
                       <ItemsControl.ItemTemplate>
                           <DataTemplate>
                               <Border BorderBrush="DarkGray" BorderThickness="1" Margin="25,2,0,2" CornerRadius="5">
                                   <Grid HorizontalAlignment="Stretch" ShowGridLines="False" Background="Transparent" Margin="0,1,0,1">
                                       <Grid.ColumnDefinitions>
                                           <ColumnDefinition Width=".4*"/>
                                           <ColumnDefinition Width=".16*"/>
                                           <ColumnDefinition Width=".44*"/>
                                       </Grid.ColumnDefinitions>
                                       <Grid.RowDefinitions>
                                           <RowDefinition Height="*"/>
                                           <RowDefinition Height="*"/>
                                       </Grid.RowDefinitions>
                                       <TextBlock Grid.RowSpan="2" Text="{Binding Subject, Mode=OneWay}" Margin="0,0,40,0" VerticalAlignment="Center" HorizontalAlignment="Right"/>
                                       <TextBlock Grid.Row="0" Grid.Column="1" Text="{Binding Professor, Mode=OneWay}" HorizontalAlignment="Center" Margin="0,1,0,0"/>
                                       <TextBlock Grid.Row="1" Grid.Column="1" Text="{Binding Time, Mode=OneWay}" HorizontalAlignment="Center" Margin="0,1,0,0"/>
                                   </Grid>
                               </Border>
                           </DataTemplate>
                       </ItemsControl.ItemTemplate>
                   </ItemsControl>
               </DataTemplate>
           </telerik:RadGridView.RowDetailsTemplate>
       </Controls:RadGridView>

Here is my code behind C#.net (Portion of It)

public MainPage()
        {
            InitializeComponent();
            DataContext = this;
            People = new ObservableCollection<Person>(GetPeople());
            EnterClasses();
            PeopleGrid.ItemsSource = People;
        }

public ObservableCollection<Person> People {get; set;}

 private List<Person> GetPeople()
        {
            var returnPeople = new List<Person>
                                   {
                                       new Person() {ID = "1234", FirstName = "John", LastName = "Berry"},
                                       new Person() {ID = "3512", FirstName = "Mary", LastName = "Edwards"},
                                       new Person() {ID = "1254", FirstName = "Henry", LastName = "Mas"},
                                       new Person() {ID = "0932", FirstName = "Terry", LastName = "Williams"},
                                       new Person() {ID = "3512", FirstName = "Beth", LastName = "Johnson"},
                                       new Person() {ID = "1254", FirstName = "Summer", LastName = "Sanford"}
                                   };

            return returnPeople;
        }

   private void EnterClasses()
        {
            var c1 = new ClassSubject()
                        {Professor = "Dr. John Dyer", Subject = "Biology", Time = "3PM - 4:30PM", UniqueId = "53913"};
            var c2 = new ClassSubject() { Professor = "Dr. George Berry", Subject = "Math", Time = "1PM - 2:00PM", UniqueId = "52973" };


            var classSchedule = new List<ClassSubject>
                                    {
                                        new ClassSubject() {Professor = "Dr. John Dyer", Subject = "Biology", Time = "3PM - 4:30PM", UniqueId = "53913"},
                                        new ClassSubject() {Professor = "Dr. Ron Maher", Subject = "Physics", Time = "3PM - 4:30PM", UniqueId = "53913"},
                                        new ClassSubject() {Professor = "Dr. George Berry", Subject = "Math", Time = "1PM - 2:00PM", UniqueId = "52973"}
                                    };
            foreach (var p in People)
            {
                p.ClassList = new ObservableCollection<ClassSubject>(classSchedule);
            }
        }

    private void PeopleGrid_RowIsExpandedChanging(object sender, Telerik.Windows.Controls.GridView.RowCancelEventArgs e)
        {
            var methodcalled = "Row Expanded";
        }

The event handler PeopleGrid_RowIsExpandedChanging was never called when I expanded a particular row.

[Top Gun]

I figured it out.  The grid has a list of Person objects.  Each Person has a list of objects <ClassSubject> .  When I click on the "+ sign" Expand button, the row expands and displays objects <ClassSubject>.

The Person object has an observable collection:

private ObservableCollection<ClassSubject> _classList;
       public ObservableCollection<ClassSubject> ClassList
       {
           get { return _classList; }
           set { _classList = value; }
       }

The View (RadGrid) will call the get attribute on the ClassListProperty when the row needs to expand.  So in the get "getter" of ClassList you can put a method to make a database call.

private ObservableCollection<ClassSubject> _classList;
       public ObservableCollection<ClassSubject> ClassList
       {
           get
          {
          CALLDBHERE();  //Make the call here
          return _classList;
            }
           set { _classList = value; }
       }

[Yordanka]

Hi Top Gun,

We have already replied to the other forum thread started by you.
 
Kind regards,
Yordanka
the Telerik team