Change DataGrid ItemsSource binding in code-behind

Question

I need to be able to change the binding of a DataGrid in the code-behind if the DataGrid does not have items within it, and vice versa.

As it stands, here is what my current attempt looks like:

C#:

List<Character> Characters = new List<Character>
            {
                new Character("Judge Dredd", Gender.Male, CharacterClass.Fighter),
                new Character("Princess Xena", Gender.Female, CharacterClass.Fighter),
                new Character("Hawkeye", Gender.Male, CharacterClass.Ranger),
                new Character("Laura Croft", Gender.Female, CharacterClass.Ranger),
                new Character("Merlin", Gender.Male, CharacterClass.Mage),
                new Character("Wicked Witch of the West", Gender.Female, CharacterClass.Mage)

            };

HeroBox.ItemsSource = Characters;

WPF:

<DataGrid x:Name="InvGrid"
          Background="DimGray"
          Grid.Column="1"
          ItemsSource="{Binding ElementName=HeroBox, Path=SelectedValue.Inventory}"
          AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridCheckBoxColumn Header="Equip"
                                Binding="{Binding Path=Equipped, Mode=TwoWay}"></DataGridCheckBoxColumn>
        <DataGridTextColumn Header="Name"
                            Binding="{Binding Path=Name, Mode=TwoWay}"></DataGridTextColumn>
        <DataGridTextColumn Header="Effect"
                            Binding="{Binding Path=Effect, Mode=TwoWay}"></DataGridTextColumn>
        <DataGridTextColumn Header="Cost"
                            Binding="{Binding Path=Cost, Mode=TwoWay}"></DataGridTextColumn>
    </DataGrid.Columns>
</DataGrid>

Attempt to change ItemsSource of InvGrid - includes compilation errors(C#):

if (InvGrid.Items.Count == 0)
{
    Binding b = new Binding("HeroBox")
    {
        ElementName = "HeroBox",
        Path = "SelectedValue.Inventory"
    };
    InvGrid.ItemsSource = new Binding(b);
} 
else
{
    InvGrid.ItemsSource = null;
}

Essentially, I would like to achieve the same effect here:

ItemsSource="{Binding ElementName=HeroBox, Path=SelectedValue.Inventory}"

But in C#.

The InvGrid DataGrid pulls its data from the Inventory of the selected hero from the ComboBox (HeroBox) which is randomly generated at runtime. Afterwards, the DataGrid should allow for the user to enter anything without automatically generating anything, yet at the moment the DataGrid randomly generates a new random item in the inventory, allowing the user to change it from there.

score 0 · Answer 1 · answered Aug 08 '14 at 22:46

Don't bind the itemssource of the datagrid. Instead implement the selectionchanged event of the combobox and set invgrid.itemssource = ((character)HeroBox.selectedItem).inventory within it (adding the necessary code is case HeroBox.selectedItem is null)

score 0 · Accepted Answer · edited May 23 '17 at 12:01

You might consider binding to a list of type ObservableCollection<Character> instead of List<Character> because it has INotifyCollectionChanged implemented already which helps you inform the UI that something has changed and it needs to update.

Here some helpful links:

What is the use of an observable Collection?
For swapping out data in the DataGrid: Replace entire ObservableCollection with Another ObservableCollection

Change DataGrid ItemsSource binding in code-behind

2 Answers2