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hi,i joined 2x tables together and bound the items to my datagrideview(membersdataGrid),and thats worked but i can't reach id or anything else in my datagrid here is my code
C#
private void Load()
        {
             var st = (from s in db.RegFee_Tbl
                      join o in db.User_Tbl on s.NumberPhone equals o.NumberPhone
                      select new { s.ID, s.RegTime, s.NumberPhone, o.FatherName, o.Name}).ToList();

            membersdataGrid.ItemsSource = st;
            datagrid = membersdataGrid;
        }

i use above method to bind joined tables into my datagrid(membersdataGrid),and in my datagrid i have a button to delete selected row,in my buttuon click event i use this code to reach selected row id and delete that row:
C#
RegFee_Tbl bluser = new RegFee_Tbl();
int id = (memebersdataGrid.SelectedItem as RegFee_Tbl).ID;
bluser.Delete(id);


What I have tried:

C#
RegFee_Tbl bluser = new RegFee_Tbl();
int id = (memebersdataGrid.SelectedItem as ****).ID;
bluser.Delete(id);

**** is my problem i know i must use st(st is my query name for joining table together) here but when i using st i got this Erro > 'st' is a variable but is used like a type
Posted
Updated 6-Feb-23 4:54am
Comments
Richard MacCutchan 6-Feb-23 10:42am    
Show the actual line of code that causes the problem.

1 solution

You've created an anonymous type[^] to represent the projection. There is generally no way to cast that to an object and read its properties short of reflection.

One simple but fragile approach would be to use C#'s dynamic type[^], which will hide the reflection code from you:
C#
dynamic selectedItem = memebersdataGrid.SelectedItem;
int id = selectedItem.ID; // <- Reflection magic happens here...
The major down-side is that you will have no intellisense, and no compile-time checks. If you spell the property name wrong, or use the wrong case, you'll find out at runtime when you get a RuntimeBinderException thrown.

Rolling your own reflection won't be any better, and will potentially decrease the performance:
C#
object selectedItem = memebersdataGrid.SelectedItem;
Type itemType = selectedItem.GetType();
PropertyInfo prop = itemType.GetProperty("ID");
int id = (int)prop.GetValue(selectedItem, null);

The safer solution is to create a specific class to represent the projection, and use that instead:
C#
public class MemberProjection
{
    public int ID { get; set; }
    public DateTime? RegTime { get; set; }
    public string NumberPhone { get; set; }
    public string FatherName { get; set; }
    public string Name { get; set; }
}

...

private void Load()
{
     var st = (from s in db.RegFee_Tbl
              join o in db.User_Tbl on s.NumberPhone equals o.NumberPhone
              select new MemberProjection { ID = s.ID, RegTime = s.RegTime, NumberPhone = s.NumberPhone, FatherName = o.FatherName, Name = o.Name }).ToList();

    membersdataGrid.ItemsSource = st;
    datagrid = membersdataGrid;
}

...

int id = ((MemberProjection)memebersdataGrid.SelectedItem).ID;

NB: With any of these approaches, remember that the SelectedItem may be null. You'll want to check for that before trying to access one of its properties.
 
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Comments
Max Speed 2022 6-Feb-23 12:57pm    
thank you so much sir,that's work, and again thank you for your attention and explain very good

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