GridView RowEditing event only fires on alternate rows - 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:TemplateField HeaderText="Department" ControlStyle-Width="175px">
<EditItemTemplate>
<asp:Label ID="lblDepartment" runat="server" Text='<%# Bind("Department") %>'></asp:Label>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="lblDepartment" runat="server" Text='<%# Bind("Department") %>'></asp:Label>
</ItemTemplate>
<ControlStyle Width="175px" />
</asp:TemplateField>
<asp:TemplateField HeaderText="Manager Level 1" ControlStyle-Width="175px">
<ItemTemplate>
<asp:Label ID="lblManager1" runat="server" Text=""></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="cbManager1" runat="server"></asp:DropDownList>
</EditItemTemplate>
<ControlStyle Width="175px" />
</asp:TemplateField>
<asp:TemplateField HeaderText="Manager Level 2" ControlStyle-Width="175px">
<ItemTemplate>
<asp:Label ID="lblManager2" runat="server" Text=""></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="cbManager2" runat="server"></asp:DropDownList>
</EditItemTemplate>
<ControlStyle Width="175px" />
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton ID="btnEdit" CommandName="Edit" runat="server" Text="Edit" CssClass="buttonStyle" CausesValidation="false"/>
</ItemTemplate>
<EditItemTemplate>
<asp:LinkButton ID="btnSave" CommandName="Update" runat="server" Text="Save" CssClass="buttonStyle" CausesValidation="false"/>
<asp:LinkButton ID="btnCancel" CommandName="Cancel" runat="server" Text="Cancel" CssClass="buttonStyle" CausesValidation="false" />
</EditItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton ID="btnDelete" CommandName="Delete" runat="server" Text="Delete" CssClass="buttonStyle" CausesValidation="false" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
The BoundField is populated in the Page_Load event as below:
Dim dHandler As DepartmentHandler = New DepartmentHandler
Dim depts As New List(Of Department)
depts = dHandler.GetDepartmentList
gvChain.DataSource = depts.
If Not Page.IsPostBack Then
gvChain.DataBind()
End If
Populating of the TemplateFields is then done in the RowDataBound event as below:
If e.Row.RowType = DataControlRowType.DataRow Then
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
' Get the list of managers
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()
' Get the department name from the label in cell 0
Dim lbl As Label = e.Row.Cells(0).FindControl("lblDepartment")
Dim dept As Department = New Department
dept.Department = lbl.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)
' Upper case the manager name to search the DDLs for item
Dim mgr1Name As String = mgr1.Name.ToUpper()
Dim mgr2Name As String = mgr2.Name.ToUpper()
' Find the manager in the DDL and select
cbManager1.SelectedValue = mgr1Name
cbManager2.SelectedValue = mgr2Name
Else
' If GV isnt in edit mode then populate labels in itemtemplate with manager 1 and 2 values
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 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)
lblManager1.Text = mgr1.Name
lblManager2.Text = mgr2.Name
End If
End If
I then have the below in the RowEditing event
gvChain.EditIndex = e.NewEditIndex
gvChain.DataBind()
When there is only 1 record displayed in the GridView, I click the edit button and the GridView goes into Edit mode I am able to update that record using the RowUpdating event and this works fine. However, if I add another record to the GridView, clicking on the edit button of that record gives a NullReference exception. If I then add another record, that 3rd record will go into edit mode. A 4th record will again fail with a NullReference exception and so on.
When debugging, it seems that on rows indexes 1,3,5 etc. the GridView doesn't go into edit mode however on row indexes 0, 2, 4 etc. the GridView will switch to edit mode.
This seems really strange behaviour. Any ideas what may be causing the GridView not to go into Edit mode on these rows?

Answer 1

A row's state can be one or a combination of the DataControlRowState values, so use bitwise operations to determine whether the state of the row includes a DataControlRowState value.
here
RowState contains more than one value (Alternate | Edit if you check RowState property during edit mode) using bit-logic.
Try
If (e.Row.RowState And DataControlRowState.Edit) > 0 Then

Answer 2

I got round this by amending the getDepartmentList function to return the Manager1 and Manager 2 fields then databinding them in the same was as I had bound 'Department'.
I then amended the RowDataBound event to the following:
If e.Row.RowType = DataControlRowType.DataRow Then
If e.Row.RowState And 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
' Get the list of managers
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()
' Get the department name from the label in cell 0
Dim lbl As Label = e.Row.Cells(0).FindControl("lblDepartment")
Dim dept As Department = New Department
dept.Department = lbl.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)
' Upper case the manager name to search the DDLs for item
Dim mgr1Name As String = mgr1.Name.ToUpper()
Dim mgr2Name As String = mgr2.Name.ToUpper()
' Find the manager in the DDL and select
cbManager1.SelectedValue = mgr1Name
cbManager2.SelectedValue = mgr2Name
End If
End If