从数据库中删除一行和 wpf 中的 gridview

Question

I want to delete a row from gridview and database - I write some code but this code just delete the first row of my gridview. Please help me. I used Entity Framework and wpf C#.

using (AccountingEntities cntx = new AccountingEntities())
{
   Producer item = this.grdProducers.SelectedItem as Producer;
   cntx.DeleteObject(cntx.Producers.First(x => x.ID == item.ID));
   cntx.SaveChanges();
   dataPager.Source = cntx.Producers.ToList();
}

Answer 1

Maybe you should simple try:

cntx.DeleteObject(cntx.Producers.where(x => x.ID == item.ID));

// if you get my .where() code to return the entity's index you'll should be fine

This should invoke the appropiate lambda/linq. Since you use " where " the expression is applied to every "Producer"-Entity x matching item.ID

UPDATE:

From MSDN:

Deletes the record at the specified index from the data source.

DeleteObject(int rowIndex)

Well this explains a lot. Because this means, that your simply passing in the wrong argument. You need to loop through the whole Grid with a foreach or for and delete each entity with deleteObject and check before whether the object's id matches item.ID.

I am sure this would be easier by using Lambda/LINQ but I currently have no idea how this could be done otherwise.

I also found this quite interesting, you have to scroll down to "delete", the example is for a database, but still uses the grid as buffer so it should be the similiar problem.

http://www.asp.net-crawler.com/articles/LINQ/Insert-retrieve-update-delete-through-gridview-using-LINQ-to-SQL.aspx

Answer 2

I find the solution: when i open the dialog for confirming the delete action, selected item changed. i should select the entityId before opening the dialog . the below code show how to do this:

            int unitTypeId = (this.grdUnitTypes.SelectedItem as UnitType).ID;
            ConfirmWindowResult result = Helpers.ShowConfirm(this, SR.GlobalMessages.AreYouSureToDelete, SR.GlobalMessages.Warning);
            if (result == ConfirmWindowResult.Yes)
            {
                using (AccountingEntities cntx = new AccountingEntities())
                {
                    try
                    {
                        cntx.UnitTypes.DeleteObject(cntx.UnitTypes.First(x => x.ID == unitTypeId));
                        cntx.SaveChanges();
                        dataPager.Source = cntx.UnitTypes.ToList();
                        MessageBox.Show("Success");
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show("Error");
                    }
                    finally
                    {
                        cntx.Dispose();
                    }
                }
            }