[Solved] Parent-Child SelectionChanged Event

[glen]

Dear Telerik,

I have a GridView with a Hierarchy setup, similar to your First Look example, however the gridview SelectionChanged event fires whether the parent or child event is changed. 

How would you recommend working out which one has actually changed and getting the relevant data back from the row selected?

Cheers

Glen

[Rossen Hristov]

Hello glen,

Along with attaching to the SelectionChanged event of the parent grid, you will need to attach to the SelectionChanged event of the RadGridView inside the HierarchyChildTemplate in order to receive notifications about the child grids.

Here is a small XAML snippet that demonstrates that:

<UserControl x:Class="Hierarchy.Page"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Width="400" Height="300"
    xmlns:telerik="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.GridView"
             >
    <Grid x:Name="LayoutRoot" Background="White">
        <telerik:RadGridView
            x:Name="RadGridView1"
            AutoGenerateColumns="False"
            SelectionChanged="ParentGrid_SelectionChanged">
            <telerik:RadGridView.Columns>
                <telerik:GridViewDataColumn HeaderText="Department" DataMemberBinding="{Binding DepartmentName}" />
                <telerik:GridViewDataColumn HeaderText="Staff count" DataMemberBinding="{Binding StaffCount}" />
            </telerik:RadGridView.Columns>

            <telerik:RadGridView.HierarchyChildTemplate>
                <DataTemplate>
                    <StackPanel DataContext="{x:Null}">
                        <telerik:RadGridView
                            Width="200"
                            Loaded="RadGridView_Loaded"
                            SelectionChanged="ChildGrid_SelectionChanged"
                            ItemsSource="{Binding Staff}"
                            ShowGroupPanel="False"
                            Margin="20"
                            IsFilteringAllowed="False"
                            AutoGenerateColumns="False">
                            <telerik:RadGridView.Columns>
                                <telerik:GridViewDataColumn HeaderText="First Name" DataMemberBinding="{Binding FirstName}" />
                                <telerik:GridViewDataColumn HeaderText="Last Name" DataMemberBinding="{Binding LastName}" />
                            </telerik:RadGridView.Columns>
                        </telerik:RadGridView>
                    </StackPanel>
                </DataTemplate>
            </telerik:RadGridView.HierarchyChildTemplate>
        </telerik:RadGridView>
    </Grid>
</UserControl>

In the event handler, you can obtain information about the data by casting the AddedRecords property of the SelectionChangedEventArgs to DataRecord:

        void RadGridView1_SelectionChanged(object sender, SelectionChangeEventArgs e)
        {
            if (e.AddedRecords.Count > 0)
            {
                DataRecord record = e.AddedRecords[0] as DataRecord;
                var dataRecord = record as DataRecord;
                if (dataRecord != null)
                {
                    MessageBox.Show(dataRecord.Data.ToString());
                }
            }
        }

Please, let me know if this does not help or you need another functionality.

Sincerely yours,
Ross
the Telerik team

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[glen]

Hi Ross,

I create the Child data like your First Look demo :

void Example_Loaded(object sender, RoutedEventArgs e)

            TableRelation relation = new TableRelation();
            relation.FieldNames.Add(new FieldDescriptorNamePair("EmployeeID", "EmployeeID"));

            GridViewTableDefinition definition = new GridViewTableDefinition();
            definition.AutoGenerateFieldDescriptors = false;

etc etc

so I am trying to work out where, in this code-behind, I attach the SelectionChanged event ??

Glen

[Rossen Hristov]

Hi glen,

In the demo you are talking about, if you check the XAML file you will see that there is a HierarchyChildTemplate. It is much more complex than the one I provided, but the idea is the same. There is nothing wrong with attaching the event handler in the XAML file. In this way it will be attached to every child grid that is created.

Anyway, it seems very reasonable that attaching a SelectionChanged event handler to the parent grid should also provide notification when the selection is changed in one of its child grids, so we will invesitgate and fix this.

Until then our suggestion is to manually attach the event handler to the grid in the HierarchyChildTemplate in the XAML file.

Please, excuse us for the inconvenience.

Sincerely yours,
Ross
the Telerik team

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