Question

Has anyone managed to bind a DataNavigator and a DataGrid using the DataSource property and the ADO.NET Entity Framework so that add and delete (+ and – buttons in the data navigator). work? I have the problem, that everytime i click on the add button of the DataNavigator, the EntityState is always set to detached. I can’t figure out, how to add this detached entity to the DataContext.

my code is simple (using a static session class and a partial class):

internal class Session
{
    private static Entities _entities;

    public static Entities Entities
    {
        get { return _entities ?? (_entities = new Entities()); }
        set { _entities = value; }
    }
}

---

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        InitData();
    }

    private void InitData()
    {
        gridControl1.DataSource = Session.Entities.SomeObjects;
        dataNavigator1.DataSource = Session.Entities.SomeObjects;
    }
}

---

public partial class SomeObjects
{
    public SomeObjects()
    {
        PropertyChanged += SomeObject_PropertyChanged;
        ObjectId = Guid.NewGuid();
    }

    private void SomeObject_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
            Debug.WriteLine(EntityState); // when i change a existing record in the grid, EntityState is set to modified and can be saved easily using SaveChanges. But when i add a new entity, EntityState is always set to detached.
    }
}

Help’s appreciated!

-christian

Answer 1

I think you should use BindingSource control instead of using DataSource and handle AddingNew event to manually set State to Added by calling AddObject.

DataGrid doesn’t know anything about source of data so it cannot communicate with entity framework context / set and add object. You must do it manually and for that you need some event to handle when new record is added. I believe AddingNew and BindingSource is way to go.