Need to populate a Dropdown combo box in Gridview, (unbound column) - vb.net

Question

I'm having difficulty populating a dropdown list in my gridview.
I have created the column with the code below:
If Not Me.GridViewIsConstructed Then
gv.Columns.Add(createComboBoxWithDDL(Me.ddlGPField.Items, "Bank_GP_Field_Name", "GPField"))
gv.Columns.Add(createComboBoxWithDDL(Me.ddlBankField.Items, "Bank_Bank_Field_Name", "BankField"))
End IF
Private Function createComboBoxWithDDL(ByVal obj As Object, ByVal nDataFieldName As String, ByVal nColName As String) As DataGridViewComboBoxColumn
Dim combo As New DataGridViewComboBoxColumn
combo.DataSource = obj
combo.DataPropertyName = nDataFieldName
combo.Name = nColName
Return combo
End Function
The problem is that I cannot get the formatting handle to populate the combo box with the index that I need. here is my code attempts for the BankField DropDown List.
If e.ColumnIndex = gv.Columns("BankField").Index Then
e.FormattingApplied = True
Dim _row = gv.Rows(e.RowIndex)
Dim _cell As New DataGridViewComboBoxColumn
fillGPFieldList(_cell)
_cell.DisplayIndex = 1
_cell.DisplayMember = "Credit"
_cell.ValueMember = "Credit"
_cell.DataSource = _cell.Items
e.Value = _cell
End If
If e.ColumnIndex = gv.Columns("TrxType").Index Then
e.FormattingApplied = True
e.Value = "BAL"
End If
The Gridview displays the dropdown object just fine, its just always set to index -1.
Please help
V*********** Addendum Edit ***********V
Unfortunately, no one answered my question. So I worked around the entire problem. Its ugly and I would greatly appreciate any feedback.
I was never able to get the ComboBox to bind to the data source. I tried everything until I turned blue. So I went to the basics and coded all the automatic stuff. I'm curious as to why the automatic binding didn't work. Perhaps its because my gridview datasource was LINQ.
Here is how I pulled it off. I hope someone down the road benefits from the last 48 hours of my delima:
First of all, know that I have two drop down lists on my form, one is the GPField and the other is the BankField. These are already populated DDLs that are static. So I used them to cheat on the values instead of using enums.
I don't think it matters, but here is how I fill the GPField and BankField:
Sub fillGPFieldListDDL(ByVal obj As Object)
Dim db As New CompanyDataDataContext
Dim myConn As New Connection With {.ConnCls = ConnCls}
myConn.dbConnect(db)
'Setup the GP Field list
obj.Items.Clear()
For Each fld In db.getGPFieldList(Me.ddlImportID.SelectedItem, ddlImportTypes.BNKREC_IMPORTS_WORK)
obj.Items.Add(fld.Trim)
Next
db.Connection.Close()
db.Connection.Dispose()
db.Dispose()
End Sub
Sub fillBankFieldListDDL(ByVal obj As Object)
If String.IsNullOrEmpty(ddlImportID.Text) Then
Return
End If
Dim db As New CompanyDataDataContext
Dim myConn As New Connection With {.ConnCls = ConnCls}
myConn.dbConnect(db)
'Setup the Bank Field list
obj.Items.Clear()
For Each fld In db.getImportIDVirtualFields(Me.ddlImportID.Text, ddlImportTypes.BNKREC_IMPORTS_WORK)
obj.Items.Add(fld.Trim)
Next
db.Connection.Close()
db.Connection.Dispose()
db.Dispose()
End Sub
Next, based on a selection from the user, I populate my grid with the following function:
Function fillToleranceFieldsGridView(ByVal nTrxType As String) As Integer
Dim myConn As New Connection With {.ConnCls = ConnCls}
Try
Using db As New CompanyDataDataContext
myConn.dbConnect(db)
'Dim _query As IEnumerable(Of TWO_Tolerance_Field) = (From tf In db.getToleranceSetupRecordFields(nTrxType, BankToleranceRecordTypes.MasterRecord) _
' Select tf)
'Dim _query2 As IEnumerable(Of TWO_Tolerance_Field) = db.getToleranceSetupRecordFields(nTrxType, BankToleranceRecordTypes.MasterRecord)
Dim _query3 = (From t In db.TWO_Tolerance_Fields _
Where t.TRXTYPESTRING = nTrxType And t.RCRDTYPE = BankToleranceRecordTypes.MasterRecord _
Select t.Bank_Bank_Field_Number, t.Bank_GP_Field_Name, t.TRXTYPESTRING)
Dim gv = Me.DataGridViewX1
gv.AutoGenerateColumns = False
gv.AllowUserToAddRows = False
gv.AllowUserToDeleteRows = False
gv.AllowUserToResizeRows = False
gv.AutoSize = True
gv.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells
'gv.DataSource = _query3
If Not Me.GridViewIsConstructed Then
'Add in the combo box for GPField Names
Dim _comboCol As DataGridViewComboBoxColumn
_comboCol = CreateComboBoxColumn(Me.ddlGPField.Items, _
ColumnNameData.Bank_GP_Field_Name.ToString, _
FieldNames.GPField.ToString)
gv.Columns.Add(_comboCol)
_comboCol = CreateComboBoxColumn(Me.ddlBankField.Items, _
ColumnNameData.Bank_Bank_Field_Number.ToString, _
FieldNames.BankField.ToString)
gv.Columns.Add(_comboCol)
Dim col As DataGridViewColumn = _
New DataGridViewTextBoxColumn()
Dim _cell = New DataGridViewTextBoxCell
Dim _coll = New DataGridViewColumn(_cell)
Dim _colIndex As Integer = 0
''Bind to an existing column Left in for easy access for a simple text box
'_coll = New DataGridViewColumn(_cell)
'_coll.Name = ColumnNameData.Bank_GP_Field_Name.ToString
'_coll.ReadOnly = True
'_coll.HeaderText = ColumnNameData.Bank_GP_Field_Name.ToString
'_colIndex = gv.Columns.Add(_coll)
'gv.Columns(_colIndex).DataPropertyName = ColumnNameData.Bank_GP_Field_Name.ToString
Me.GridViewIsConstructed = True
End If
gv.Rows.Clear()
Dim ri As Integer = 0
For Each r In _query3
Dim _row As New DataGridViewRow
_row.CreateCells(gv)
_row.Cells(FieldNames.GPField).Value = r.Bank_GP_Field_Name.ToString.Trim
_row.Cells(FieldNames.BankField).Value = ddlBankField.Items(r.Bank_Bank_Field_Number - 1).ToString.Trim
gv.Rows.Add(_row)
ri += 1
Next
db.Connection.Close()
db.Connection.Dispose()
End Using
Return 0
Catch ex As Exception
Throw ex
Finally
myConn.Dispose()
End Try
End Function
So, the unanswered questions are:
1). I couldn't use the _query or _query2 as datasources for the gridview, but _query3 did work for simple textboxes.
2). If using _query3 as the gv.datasource, why would my combobox throw "bank_gp_field_name" not found error when the gv.Columns.Add(_comboCol) was executed
3). I understand the reason I couldn't do a gv bind to _query3 because of the data in Bank_Bank_field_number is an integer and the DDL values don't have a translation between the integer and the string value. But I commented out that field expecting the GPField to operate on a standard bind. I still got the "Field called "Bank_GP_Field_Name" does not exist on gv.Columns.Add(_comboCol)
So, summed up, why doesn't the code below work whereas the one above does?
Function fillToleranceFieldsGridView(ByVal nTrxType As String) As Integer
Dim myConn As New Connection With {.ConnCls = ConnCls}
Try
Using db As New CompanyDataDataContext
myConn.dbConnect(db)
'Dim _query As IEnumerable(Of TWO_Tolerance_Field) = (From tf In db.getToleranceSetupRecordFields(nTrxType, BankToleranceRecordTypes.MasterRecord) _
' Select tf)
'Dim _query2 As IEnumerable(Of TWO_Tolerance_Field) = db.getToleranceSetupRecordFields(nTrxType, BankToleranceRecordTypes.MasterRecord)
Dim _query3 = (From t In db.TWO_Tolerance_Fields _
Where t.TRXTYPESTRING = nTrxType And t.RCRDTYPE = BankToleranceRecordTypes.MasterRecord _
Select t.Bank_Bank_Field_Number, t.Bank_GP_Field_Name, t.TRXTYPESTRING)
Dim gv = Me.DataGridViewX1
gv.AutoGenerateColumns = False
gv.AllowUserToAddRows = False
gv.AllowUserToDeleteRows = False
gv.AllowUserToResizeRows = False
gv.AutoSize = True
gv.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells
gv.DataSource = _query3
If Not Me.GridViewIsConstructed Then
'Add in the combo box for GPField Names
Dim _comboCol As DataGridViewComboBoxColumn
_comboCol = CreateComboBoxColumn(Me.ddlGPField.Items, _
ColumnNameData.Bank_GP_Field_Name.ToString, _
FieldNames.GPField.ToString)
gv.Columns.Add(_comboCol)
'_comboCol = CreateComboBoxColumn(Me.ddlBankField.Items, _
' ColumnNameData.Bank_Bank_Field_Number.ToString, _
' FieldNames.BankField.ToString)
'gv.Columns.Add(_comboCol)
Dim col As DataGridViewColumn = _
New DataGridViewTextBoxColumn()
Dim _cell = New DataGridViewTextBoxCell
Dim _coll = New DataGridViewColumn(_cell)
Dim _colIndex As Integer = 0
''Bind to an existing column Left in for easy access for a simple text box
'_coll = New DataGridViewColumn(_cell)
'_coll.Name = ColumnNameData.Bank_GP_Field_Name.ToString
'_coll.ReadOnly = True
'_coll.HeaderText = ColumnNameData.Bank_GP_Field_Name.ToString
'_colIndex = gv.Columns.Add(_coll)
'gv.Columns(_colIndex).DataPropertyName = ColumnNameData.Bank_GP_Field_Name.ToString
Me.GridViewIsConstructed = True
End If
'gv.Rows.Clear()
'Dim ri As Integer = 0
'For Each r In _query3
' Dim _row As New DataGridViewRow
' _row.CreateCells(gv)
' _row.Cells(FieldNames.GPField).Value = r.Bank_GP_Field_Name.ToString.Trim
' _row.Cells(FieldNames.BankField).Value = ddlBankField.Items(r.Bank_Bank_Field_Number - 1).ToString.Trim
' gv.Rows.Add(_row)
' ri += 1
'Next
db.Connection.Close()
db.Connection.Dispose()
End Using
Return 0
Catch ex As Exception
Throw ex
Finally
myConn.Dispose()
End Try
End Function
Private Function CreateComboBoxColumn(ByVal obj As ComboBox.ObjectCollection, ByVal nDataFieldName As String, ByVal nColName As String) _
As DataGridViewComboBoxColumn
Dim column As New DataGridViewComboBoxColumn()
With (column)
.HeaderText = nColName
.DropDownWidth = 160
.Width = 90
.MaxDropDownItems = 3
.FlatStyle = FlatStyle.Flat
.DataSource = obj
.DataPropertyName = nDataFieldName
.Name = nColName
.ValueMember = nDataFieldName
.DisplayMember = .ValueMember
End With
Return column
End Function

Answer 1

Sorry if I've misunderstood or over simplified this but from what I gather the combox is binding fine you just cant set the index to 1? Is this because there is no underlying data for that cell?
Have you tried setting the default value of the column? From what I've read DataGridViewComboBoxColumn doesn't have a cell DefaultValue but works with column default.
Columns("ColumName").DefaultValue = 1
http://msdn.microsoft.com/en-us/library/system.data.datacolumn.defaultvalue.aspx
You could also try handling DefaultValuesNeeded
Private Sub gv_DefaultValuesNeeded(ByVal sender As Object, _
ByVal e As System.Windows.Forms.DataGridViewRowEventArgs) _
Handles gv.DefaultValuesNeeded
With e.Row
.Cells("GPField") = 1
.Cells("BankField") = 1
End With
End Sub
http://msdn.microsoft.com/en-us/library/system.windows.forms.datagridview.defaultvaluesneeded(v=vs.110).aspx