Gridview with Dictionary - asp.net

Question

I've created a Dictionary like
Dictionary<Department,bool> dict= new Dictionary<Department,bool>();
here Department is a class and I have Id,Name and Code for the departments. And in the bool am sending whether the person is HOD or not.
Am adding the records to this Dictionary like
dict.Add(department,chkHOD.checked);
here the records are successfully added to the Dictionary and after this am binding the Dictionary to a GridView like
gridDept.Datasource=dict;
gridDept.Databind();
now the inserted records are displayed fine in the gridview. After this am storing this records in the 'StaffDepartments' table in my database. I have 3 columns in the 'Staffdepartments' table
1.StaffId(PK - has link with the Staff table)
2.DepartmentId(PK - has link with the Department table)
3.IsHOD.
here the records are stored fine in the database.No problem in adding the records into the database.
I have some questions here
*1.How can check whether the DepartmentId is already there in the Dictionary before adding to it.
2.When am editing the staff detail how can I delete the Selected Department from the Dictionary by checking the checkbox in Gridview rows.(here the records are coming from the database, so when I click delete button the records should be deleted in the database as well)*
if its a List instead of Dictionary, I can get the DepartmentId by
int departmentId = (int)gridDept.DataKeys[row.RowIndex].Values["DepartmentId"];
but in Dictionary i dunno how to do the same with Key and Value pairs....can anyone help me here.

Answer 1

How can check whether the DepartmentId is already there in the
Dictionary before adding to it.
You could use this:
if (!dict.Keys.Any(d => d.DepartmentId == department.DepartmentId))
dict.Add(department,chkHOD.checked);
But something is wrong here. If your real key is the DepartmentId and not the Department (object identity) you should make it the key in the dictionary. For example, you could define a helper class:
public class DepartmentBindingHelper
{
public int DepartmentId { get; set; }
public Department Department { get; set; }
public bool Checked { get; set; }
}
An then define a dictionary like this:
var dict = new Dictionary<int, DepartmentBindingHelper>();
And add the objects this way to the dictionary:
if (!dict.ContainsKey(department.DepartmentId))
dict.Add(department.DepartmentId, new DepartmentBindingHelper
{
DepartmentId = department.DepartmentId,
Department = department,
Checked = chkHOD.checked
});
Then you can bind only the value collection to the grid:
gridDept.Datasource = dict.Values;// it's an IEnumerable<DepartmentBindingHelper>
gridDept.Databind();
And your code to retrieve the DepartmentId from a row would work without changes:
int departmentId = (int)gridDept.DataKeys[row.RowIndex].Values["DepartmentId"];