Linq-to-sql to Combobox binding (Winforms)

Question

I have a WinForm. At this form I show data from table row. I have tables Comments and Users:

Comments :{ ID(int),Text(NVarchar), UserId(int) }

Users: { ID(int), Name(NVarChar) }

At a form I have TextBox and Combobox. In Textbox I won't show "Text" from Comments (user can edit this field, data must be saved in a table) and Name from table Users (where Comments.UserId = Users.ID).

I have following code:

FormDataClassesDataContext dc = new FormDataClassesDataContext(); 

_comment = (from comment in dc.Comments
                    where comment.ID == 1
                    select comment).FirstOrDefault();
_user = (from users in dc.Users
                     where users.ID == _comment.UserId
                     select users).FirstOrDefault();

textBoxComment.DataBindings.Add("Text", _comment, "Text"); // <-OK
comboBoxAssessor.DataSource = dc.Users;
comboBoxAssessor.DisplayMember = "Name";
comboBoxAssessor.ValueMember = "ID";
comboBoxAssessor.DataBindings.Add("SelectedItem", _comment, "UserId");

and then

dc.SubmitChanges();

but I become "Unable to pass "MyApp.Forms.User" to "Int32"

Answer 1

The selected item of a combobox is the current object in its data source, in this case: a User . You must use SelectedValue :

comboBoxAssessor.DataBindings.Add("SelectedValue", _comment, "UserId");

which returns the value of the property you define in the ValueMember .

Answer 2

SelectedItem should be of type User if I don't make a mistake. And you bind Comment.UserId (int) to it.