DataGridView ComboBox column that will accept any text - Dropdown populated by Column

Question

https://stackoverflow.com/a/59545459/20359642

Hi, on the article above, I grabbed the code snippet from Sidupac. This class works but it has a different drop down list for each row. I want each row to be populated with the same list. I am not very good at classes, can someone please help? My goal is to be able to add a column to a DataGridView that will act as a combobox but also accepts manual text input as well.

Public Class DataGridViewDropDownComboBoxColumn
    Inherits DataGridViewColumn

    Public Sub New()
        MyBase.New(New DataGridViewDropDownComboBoxCell)

    End Sub

    Public Property DropDownStyle As ComboBoxStyle
    Public Property DataSource As Object
    Public Property ValueMember As Object
    Public Property DisplayMember As Object

    Public Overrides Property CellTemplate As DataGridViewCell
        Get
            Return MyBase.CellTemplate
        End Get
        Set
            ' Ensure that the cell used for the template is a DataGridViewDropDownComboBoxCell.
            If ((Not (Value) Is Nothing) AndAlso Not Value.GetType.IsAssignableFrom(GetType(DataGridViewDropDownComboBoxCell))) Then
                Throw New InvalidCastException("Must be a DropDownCell")
            End If

            MyBase.CellTemplate = Value
        End Set
    End Property
End Class

Public Class DataGridViewDropDownComboBoxCell
    Inherits DataGridViewTextBoxCell


    Public Sub New()
        MyBase.New
    End Sub

    Public Overrides Sub InitializeEditingControl(ByVal rowIndex As Integer, ByVal initialFormattedValue As Object, ByVal dataGridViewCellStyle As DataGridViewCellStyle)
        ' Set the value of the editing control to the current cell value.
        MyBase.InitializeEditingControl(rowIndex, initialFormattedValue, dataGridViewCellStyle)
        Dim ctl As DataGridViewDropDownComboBoxEditingControl = CType(DataGridView.EditingControl, DataGridViewDropDownComboBoxEditingControl)
        ' Use the default row value when Value property is null.
        If (Me.Value Is Nothing) Or IsDBNull(Me.Value) Then
            ctl.Text = CType(Me.DefaultNewRowValue, String)
        Else
            ctl.Text = CType(Me.Value, String)
        End If
        'ctl.BringToFront()
        'ctl.Focus()
        'ctl.DroppedDown = True

    End Sub

    Public Overrides ReadOnly Property EditType As Type
        Get
            ' Return the type of the editing control that DataGridViewDropDownComboBoxCell uses.
            Return GetType(DataGridViewDropDownComboBoxEditingControl)
        End Get
    End Property

    Public Overrides ReadOnly Property ValueType As Type
        Get
            ' Return the type of the value that DataGridViewDropDownComboBoxCell contains.
            Return GetType(String)
        End Get
    End Property

    Public Overrides ReadOnly Property DefaultNewRowValue As Object
        Get
            ' Use the current date and time as the default value.
            Return ""
        End Get
    End Property
End Class
Class DataGridViewDropDownComboBoxEditingControl
    Inherits ComboBox
    Implements IDataGridViewEditingControl

    Private dataGridView As DataGridView

    Private valueChanged As Boolean = False

    Private rowIndex As Integer

    Public Sub New()
        MyBase.New
    End Sub

    Public Shadows Property DropDownStyle() As ComboBoxStyle
        Get
            Return MyBase.DropDownStyle
        End Get
        Set(ByVal value As ComboBoxStyle)
            If value = ComboBoxStyle.Simple Then
                'Throw New NotSupportedException("ComboBoxStyle.Simple not supported")
                value = ComboBoxStyle.DropDown
            End If
            MyBase.DropDownStyle = value
        End Set
    End Property

    ' Implements the IDataGridViewEditingControl.EditingControlFormattedValue 
    ' property.
    Public Property EditingControlFormattedValue As Object Implements IDataGridViewEditingControl.EditingControlFormattedValue
        Get
            Return Me.Text
        End Get
        Set
            If (TypeOf Value Is String) Then
                Me.Text = CStr(Value)
            End If

        End Set
    End Property

    ' Implements the 
    ' IDataGridViewEditingControl.GetEditingControlFormattedValue method.
    Public Function GetEditingControlFormattedValue(ByVal context As DataGridViewDataErrorContexts) As Object Implements IDataGridViewEditingControl.GetEditingControlFormattedValue
        Return Me.EditingControlFormattedValue
    End Function

    ' Implements the 
    ' IDataGridViewEditingControl.ApplyCellStyleToEditingControl method.
    Public Sub ApplyCellStyleToEditingControl(ByVal dataGridViewCellStyle As DataGridViewCellStyle) Implements IDataGridViewEditingControl.ApplyCellStyleToEditingControl
        Me.Font = dataGridViewCellStyle.Font
        Me.ForeColor = dataGridViewCellStyle.ForeColor
        Me.BackColor = dataGridViewCellStyle.BackColor
    End Sub

    ' Implements the IDataGridViewEditingControl.EditingControlRowIndex 
    ' property.
    Public Property EditingControlRowIndex As Integer Implements IDataGridViewEditingControl.EditingControlRowIndex
        Get
            Return Me.rowIndex
        End Get
        Set
            Me.rowIndex = Value
        End Set
    End Property

    ' Implements the IDataGridViewEditingControl.EditingControlWantsInputKey 
    ' method.
    Public Function EditingControlWantsInputKey(ByVal key As Keys, ByVal dataGridViewWantsInputKey As Boolean) As Boolean Implements IDataGridViewEditingControl.EditingControlWantsInputKey
        ' Let the DateTimePicker handle the keys listed.
        Select Case ((key And Keys.KeyCode))
            Case Keys.Left, Keys.Up, Keys.Down, Keys.Right, Keys.Home, Keys.End, Keys.PageDown, Keys.PageUp, Keys.F4
                Return True
            Case Else
                Return Not dataGridViewWantsInputKey
        End Select

    End Function

    ' Implements the IDataGridViewEditingControl.PrepareEditingControlForEdit 
    ' method.
    Public Sub PrepareEditingControlForEdit(ByVal selectAll As Boolean) Implements IDataGridViewEditingControl.PrepareEditingControlForEdit
        Dim col As DataGridViewDropDownComboBoxColumn = CType(dataGridView.Columns(dataGridView.CurrentCell.ColumnIndex), DataGridViewDropDownComboBoxColumn)
        If (col Is Nothing) Then
            Throw New InvalidCastException("Must be in a DropDownComboBoxColumn")
        End If


        DropDownStyle = col.DropDownStyle

        Items.Clear()
        If IsDBNull(dataGridView.CurrentCell.Value) Then
            Text = ""
        Else
            Text = CType(dataGridView.CurrentCell.Value, String)
        End If
        Items.Add(Text)

        Dim dt As DataTable = New DataTable
        Dim ct As Integer = 0, cx As Integer = 0
        Try
            dt = DirectCast(col.DataSource, DataTable)
            If Not col.DisplayMember Is Nothing Then
                For Each c As DataColumn In dt.Columns
                    If c.ColumnName Is col.DisplayMember Then
                        cx = ct
                    End If
                    ct += 1
                Next
            End If
            For Each r As DataRow In dt.Rows
                If Not col.DisplayMember Is Nothing Then
                    If Not Items.Contains(r(cx)) Then Items.Add(r(cx))
                Else
                    If dt.Columns.Count = 1 Then
                        If Not Items.Contains(r(0)) Then Items.Add(r(0))
                    Else
                        If Not Items.Contains(r(dt.Columns.Count - 1)) Then Items.Add(r(dt.Columns.Count - 1))
                    End If
                End If
            Next
        Catch ex As Exception
        End Try

        'DropDownStyle = col.DropDownStyle
        'ValueMember = col.ValueMember
        'DisplayMember = col.DisplayMember
        'DataSource = col.DataSource

        ' (If you don't explicitly set the Text then the current value is
        ' always replaced with one from the drop-down list when edit begins.)
        'If IsDBNull(dataGridView.CurrentCell.Value) Then
        '    Text = ""
        'Else
        '    Text = CType(dataGridView.CurrentCell.Value, String)
        'End If

    End Sub

    ' Implements the IDataGridViewEditingControl
    ' .RepositionEditingControlOnValueChange property.
    Public ReadOnly Property RepositionEditingControlOnValueChange As Boolean Implements IDataGridViewEditingControl.RepositionEditingControlOnValueChange
        Get
            Return False
        End Get
    End Property

    ' Implements the IDataGridViewEditingControl
    ' .EditingControlDataGridView property.
    Public Property EditingControlDataGridView As DataGridView Implements IDataGridViewEditingControl.EditingControlDataGridView
        Get
            Return Me.dataGridView
        End Get
        Set
            Me.dataGridView = Value
        End Set
    End Property

    ' Implements the IDataGridViewEditingControl
    ' .EditingControlValueChanged property.
    Public Property EditingControlValueChanged As Boolean Implements IDataGridViewEditingControl.EditingControlValueChanged
        Get
            Return Me.valueChanged
        End Get
        Set
            Me.valueChanged = Value
        End Set
    End Property

    ' Implements the IDataGridViewEditingControl
    ' .EditingPanelCursor property.
    Public ReadOnly Property EditingPanelCursor As Cursor Implements IDataGridViewEditingControl.EditingPanelCursor
        Get
            Return MyBase.Cursor
        End Get
    End Property

    Protected Overrides Sub OnTextChanged(ByVal eventargs As EventArgs)
        ' Notify the DataGridView that the contents of the cell
        ' have changed.
        Me.valueChanged = True
        Me.EditingControlDataGridView.NotifyCurrentCellDirty(True)
        MyBase.OnTextChanged(eventargs)
    End Sub

    Protected Overrides Sub OnSelectedIndexChanged(ByVal e As EventArgs)
        ' Notify the DataGridView that the contents of the cell
        ' have changed.
        Me.valueChanged = True
        Me.EditingControlDataGridView.NotifyCurrentCellDirty(True)
        MyBase.OnSelectedIndexChanged(e)
    End Sub
End Class

I've tried messing around with the class myself but I just cant seem to figure it out.

Answer 1

I actually figured it out. The DataSource was not populating the dropdowns because I was not giving it a DataTable to reference. I was giving it a string array. I just need to alter the class a bit to handle different types of inputs for the DataSource.

For example, I changed the code inside of the try statement in the PrepareEditingControlForEdit procedure to the code below:

            If TypeOf col.DataSource Is String Then
                Items.Add(col.DataSource)
            ElseIf TypeOf col.DataSource Is String() Then
                For Each obj As Object In DirectCast(col.DataSource, String())
                    Items.Add(obj)
                Next
            ElseIf TypeOf col.DataSource Is List(Of String) Then
                For Each obj As String In DirectCast(col.DataSource, List(Of String))
                    Items.Add(obj)
                Next
            ElseIf TypeOf col.DataSource Is List(Of Object) Then
                For Each obj As String In DirectCast(col.DataSource, List(Of Object))
                    Items.Add(obj)
                Next
            ElseIf TypeOf col.DataSource Is DataTable Then
                dt = DirectCast(col.DataSource, DataTable)
                If Not col.DisplayMember Is Nothing Then
                    For Each c As DataColumn In dt.Columns
                        If c.ColumnName Is col.DisplayMember Then
                            cx = ct
                        End If
                        ct += 1
                    Next
                End If
                For Each r As DataRow In dt.Rows
                    If Not col.DisplayMember Is Nothing Then
                        If Not Items.Contains(r(cx)) Then Items.Add(r(cx))
                    Else
                        If dt.Columns.Count = 1 Then
                            If Not Items.Contains(r(0)) Then Items.Add(r(0))
                        Else
                            If Not Items.Contains(r(dt.Columns.Count - 1)) Then Items.Add(r(dt.Columns.Count - 1))
                        End If
                    End If
                Next
            End If