CODEWITHSUNDEEP
c#mvvm
jDave1984
jDave1984

Reputation: 962

SelectedItem not reachable from DataGrid in RowDetailsTemplate

I have a DataGrid which holds a number of objects. Within that DataGrid, I have a RowDetailsTemplate to house all of the hierarchical data. I want to be able to select the object from within that DataGrid, but so far haven't had any luck with the following code

    <DataGrid x:Name="leagueList" Grid.Row="1" ItemsSource="{Binding Leagues}" SelectedItem="{Binding SelectedLeague}"
              Margin="0,0,5,0" ColumnWidth="1*"
              CanUserAddRows="False" AutoGenerateColumns="False" IsReadOnly="True" CanUserReorderColumns="False" CanUserSortColumns="False">
        <DataGrid.Resources>
            <utility:SubtractValueConverter x:Key="SubtractValueConverter"/>
        </DataGrid.Resources>
        <DataGrid.RowHeaderTemplate>
            <DataTemplate>
                <Expander Expanded="Expander_Expanded" Collapsed="Expander_Collapsed"/>
            </DataTemplate>
        </DataGrid.RowHeaderTemplate>
        <DataGrid.Columns>
            <DataGridTextColumn Header="League" Binding="{Binding Name}"/>
            <DataGridTextColumn Header="Initials" Binding="{Binding Initials}"/>
        </DataGrid.Columns>
        <DataGrid.RowDetailsTemplate>
            <DataTemplate DataType="{x:Type models:Team}">
                <DataGrid ItemsSource="{Binding Teams}" SelectedItem="{Binding Path=SelectedTeam, UpdateSourceTrigger=PropertyChanged}"
                          CanUserAddRows="False" AutoGenerateColumns="False" IsReadOnly="True" GridLinesVisibility="All"
                          Width="{Binding ActualWidth,ElementName=leagueList, Converter={StaticResource SubtractValueConverter}, ConverterParameter=50}" HorizontalAlignment="Stretch" ColumnWidth="*" Margin="1,1,1,1" BorderThickness="2">
                    <DataGrid.Columns>
                        <DataGridTextColumn Header="Nickname" Binding="{Binding Nickname}"/>
                    </DataGrid.Columns>
                </DataGrid>
            </DataTemplate>
        </DataGrid.RowDetailsTemplate>
    </DataGrid>

The SelectedTeam Property is what I want to be called when a Team is selected, but it doesn't appear to be bound to that property, even though I'm specifying it as such.

    public Team SelectedTeam
    {
        get => _SelectedTeam;
        set
        {
            _SelectedTeam = value;
            System.Windows.MessageBox.Show("Selected Team is: " + _SelectedTeam.Nickname);
            RaisePropertyChangedEvent("SelectedTeam");
        }
    }

When I run my app, I don't even get the MessageBox popup when I select a Team, but I should.

The entire grid populates properly, I just can't get the SelectedItem from the inner DataGrid.

Upvotes: 1

Views: 217

Answers (2)

jDave1984
jDave1984

Reputation: 962

After using both Jan's comment link and Satish's answers, I've found the solution.

The child DataGrid needs to find the DataContext of it's parent, so using RelativeResource to point to the UserControl type will work, followed by inserting DataContext in front of my property type. So the SelectedItem line of code appears as follows:

SelectedItem="{Binding Path=DataContext.SelectedTeam, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}"

Upvotes: 1

Sats
Sats

Reputation: 1973

Since it is inside the template, it is difficult to bind the selected item, what you can do is use RelativeSource, below is the syntax & example.

SelectedItem = {Binding Path=SelectedTeam, RelativeSource={RelativeSource AncestorType={x:Type typeOfAncestor}}}

typeOfAncestor :- Type of Ancestor is the type of class for which you have provided the namespace in the Declaration of Xaml, which the namespace of the viewmodel.

For example: 

xmlns:local="clr-namespace:WpfApp2"

which needs to be at the top of the xaml page

SelectedItem = {Binding Path=SelectedTeam, RelativeSource={RelativeSource AncestorType={x:Type local:ViemModelName}}}

Relative Source relates or points towards the property. Now what happens is the SelectedTeam is binded from the View Model to this Selected Item Property.

Hope this helps you. Thanks,

Upvotes: 0

Related Questions