Question

I want to display a list of notes from an object in a WPF DataGrid using MVVM

XAML:

 <DataGrid
        x:Name="NoteGrid"
        ItemsSource="{Binding NoteObj.Notes}"
        SelectedItem="{Binding CurrentNote}"
        AutoGenerateColumns="False"
        CanUserAddRows="False"
        CellEditEnding="DataGrid_CellEditEnding">
        <DataGrid.Columns>
            <DataGridTextColumn Header="Note" Binding="{Binding NoteText}" />
            <DataGridTextColumn Header="Type" Binding="{Binding Type.Name}" />
        </DataGrid.Columns>
    </DataGrid>

The return-value of NoteObj.Notes is EntitySet.

ViewModel:

private NoteObject noteObj;
public NoteObject NoteObj
{
    get { return noteObj; }
    set { noteObj = value; OnPropertyChanged("NoteObj"); }
}

public void AddNote()
{
    var note = new Note
    {
        NoteText = "Note text",
        NoteType = 1
    };

    NoteObj.Notes.Add(note);
    DC.SubmitChanges();
    OnPropertyChanged("NoteObj");
}

When NoteObj is set the DataGrid is filled with notes but the AddNote-method doesn’t wotk!
The new note is added to the database, but the DataGrid is never updated.

Is it a problem eith EntitySet or am I missing something in the XAML?

Answer 1

This will only work if NoteObj.Notes implements INotifyCollectionChanged. You can achieve this by using the class ObservableCollection<T>.