linq return using Tuple

Question

hi i just upgraded to Framework 4.0 and added relationship foreign key to my database. I would like to join 2 table User and Staff and return back to UI. Staff table has the UserId. Having to say that, whenever the user name is clicked on the datagridview, i would like to display out User and Staff data to all the textbox.

I do this using Tuple

   public IEnumerable<Tuple<User, Staff>> Get()
    {
        using (qDataContext db = new qDataContext())
        {
            try
            {
                var r = from u in db.Users
                        join s in db.Staffs on u.Id equals s.UserId
                        select new Tuple<User, Staff>(u, s);

                return r;
            }
            catch (Exception ex)
            {
                throw;
            }
        }
    }

But in UI, how should i do the binding? gvUser.DataSource = user.Get();

FYI, The gridview is just display the username. Staff table will store the password, datejoined fields..

By the way, do i still need to join tables since i have already added foreign key reference to the tables.. i am thinking of it should smart enough to return me User.Staff.Password

---

EDIT
this is what i found.. i have added relationship foreign key to my database. and the code below is already able to return me User and Staff data as Staff.UserId is pointed to UserId And i don have to use the TUPLE to return those object :)!!

 public IEnumerable<User> Get()
    {
        using (ZebraDataContext db = new ZebraDataContext())
        {
            try
            {
                var r = from u in db.Users
                        select u;
                        //join s in db.Staffs on u.Id equals s.UserId
                        //select new Tuple<User, Staff>(u, s);

                return r.ToList();
            }
            catch (Exception ex)
            {
                throw;
            }
        }
    }

However, i have trouble when i bind to the GUI datagridview.

 private void InitializeData()
    {
       gvUser.DataSource = user.Get();
    }

This code able to shows me the User data. But how do i get back the Staff data when i do the gvUser_RowEnter?

private void gvUser_RowEnter(object sender, DataGridViewCellEventArgs e) { if (e.RowIndex <= 0) return;

        foreach (DataGridViewRow row in gvUser.SelectedRows)
        {
            User user = row.DataBoundItem as User;
            txtName.Text = user.Name;
            txtAddress.Text = user.Address;
            txtPhone.Text = user.Phone;
            txtPhone2.Text = user.Phone2;
            txtRemark.Text = user.Remarks;

            txtPassword.Text = user.Staffs.First().Password;

        }
    }

txtPassword.text = user.Staffs.First().Password < == failed with this error Cannot access a disposed object. Object name: 'DataContext accessed after Dispose.'.

when i add watch the Staff object in User. i can see the data in the hidden ((User)(row.DataBoundItem)).Staffs.entities.Items this has the staff data ..

Answer 1

Rather than returning a Tuple, wouldn't returning an anonymous object do the trick? It might look something like this:

var r = from u in db.Users
    select new { u.Name, 
                 u.Address,
                 ...,
                 (from s in db.Staffs select s.Password where u.Id == s.UserId) 
               };