Populating a dropdownlist in the rowEditing event of a GridView - asp.net

Question

I have a GridView as below
<asp:GridView ID="gvChain" runat="server" Font-Size="Small" CellPadding="3" CellSpacing="1" GridLines="None" AutoGenerateColumns="False">
<headerstyle backcolor="#CCCCCC" />
<columns>
<asp:BoundField DataField="Department" HeaderText="Department" />
<asp:TemplateField HeaderText="Manager Level 1">
<ItemTemplate>
<asp:Label ID="lblManager1" runat="server" Text=""></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="cbManager1" runat="server"/>
</EditItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Manager Level 2">
<ItemTemplate>
<asp:Label ID="lblManager2" runat="server"/>
</ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="cbManager2" runat="server"/>
</EditItemTemplate>
</asp:TemplateField>
<asp:CommandField ShowEditButton="True">
<ControlStyle ForeColor="#009EDD" />
</asp:CommandField>
</columns>
</asp:GridView>
The BoundField 'Department' is being populated in the Page_Load as below which works fine and populates the GridView with a list of departments.
Dim dhandler As DepartmentHandler = New DepartmentHandler
Dim depts As New List(Of Department)
depts = dhandler.GetDepartmentList
gvChain.DataSource = depts
gvChain.DataBind()
I am then populating the ItemTemplates of the TemplateFields in the RowDAtaBound event as below. this is also working fine.
If e.Row.RowType = DataControlRowType.DataRow Then
Dim lblManager1 As Label = DirectCast(e.Row.FindControl("lblManager1"), Label)
Dim lblManager2 As Label = DirectCast(e.Row.FindControl("lblManager2"), Label)
Dim eHandler As EmployeeHandler = New EmployeeHandler
Dim deptCell As TableCell = e.Row.Cells(0)
Dim dept As Department = New Department
dept.Department = deptCell.Text
Dim mgr1 As Manager = eHandler.getManager1(dept)
Dim mgr2 As Manager = eHandler.getManager2(dept)
lblManager1.Text = mgr1.Name
lblManager2.Text = mgr2.Name
End If
What I now want to achieve is when clicking on the 'Edit' field of a row on the GridView, populate cbManager1 and cbManager2 with a list of Managers and set the SelectedValue of each DDL to the same values as I am retrieving in the item template. I can get the data with the below code in the RowEditing event of the GridView:
' Get the list of managers
Dim mgrs As New List(Of Manager)
mgrs = eHandler.GetManagerList
' Get the department name from the BoundField
Dim deptCell As TableCell = gvChain.Rows(e.NewEditIndex).Cells(0)
Dim dept As Department = New Department
dept.Department = deptCell.Text
' Pass the department name to the getManager1/2 functions to return the correct manager for that department
Dim mgr1 As Manager = eHandler.getManager1(dept)
Dim mgr2 As Manager = eHandler.getManager2(dept)
I have set breakpoints to check the data is being returned from the functions and the data is there as expected but where I am stuck is getting a reference on the DDLs in the EditItemTemplate so I can databind them and set the SelectedValue.
I have tried the below but this is giving a NullReference Exception:
Dim cbManager1 As DropDownList = TryCast(gvChain.Rows(e.NewEditIndex).FindControl("cbManager1"), DropDownList)
Dim cbManager2 As DropDownList = TryCast(gvChain.Rows(e.NewEditIndex).FindControl("cbManager2"), DropDownList)

Answer 1

I got round this in the end. I added the following code to the RowEditing event
gvChain.EditIndex = e.NewEditIndex
gvChain.DataBind()
I then did the following in the RowDataBound event
If e.Row.RowState = DataControlRowState.Edit Then
Dim cbManager1 As DropDownList = TryCast(e.Row.FindControl("cbManager1"), DropDownList)
Dim cbManager2 As DropDownList = TryCast(e.Row.FindControl("cbManager2"), DropDownList)
Dim eHandler As EmployeeHandler = New EmployeeHandler
Dim mgrs As New List(Of Manager)
mgrs = eHandler.GetManagerList
cbManager1.DataSource = mgrs
cbManager2.DataSource = mgrs
cbManager1.DataValueField = "Name"
cbManager1.DataTextField = "Name"
cbManager2.DataValueField = "Name"
cbManager2.DataValueField = "Name"
cbManager1.DataBind()
cbManager2.DataBind()
' Got rid of the bound field in the end and did it with a templatefield so needed to get the department from the label
Dim lbl As Label = e.Row.Cells(0).FindControl("lblDepartment")
Dim dept As Department = New Department
dept.Department = lbl.Text
Dim mgr1 As Manager = eHandler.getManager1(dept)
Dim mgr2 As Manager = eHandler.getManager2(dept)
Dim mgr1Name As String = mgr1.Name.ToUpper()
Dim mgr2Name As String = mgr2.Name.ToUpper()
cbManager1.SelectedValue = mgr1Name
cbManager2.SelectedValue = mgr2Name
End If

Answer 2

You could try something like this
If e.Row.RowState = DataControlRowState.Edit Then
Dim cbmanager As DropDownList = e.Row.FindControl("cbmanager1")
If Not cbmanager Is Nothing Then cbmanager.Items.Add(New ListItem("Test1", "Test1"))
End If