DataGridView Sort does not work

Question

Visual Studio 2010 VB.NET

I have a DataGridView.DataSource set to a Collection of custom objects. The columns use read only properties from the custom object for display, this dialog is for display only. The properties all return String objects. I set the columns all but 2 of them to sortmode automatic (the ones that are not set is a button or a checkbox). Yet it does not sort. I have googled around and most people use sql or binding sources but I am using a trivial vb collection. Some say I should implement IComparable but isn't String already IComparable?

Any help would be appreciated?

Thanx

Bodger

Per a request here are some code snippets.

This method defines the columns in detail from columns I designed in the designer.

The column names are called pSelected or pCustomer and corresponds with a property by the same name that the column definition ties to.

Protected Sub UpdateDGVUS()
        If Not USColumnsInitted Then
            USColumnsInitted = True

            dgvUS.AutoGenerateColumns = False
            dgvUS.Columns.Clear()

            Dim iIdx As Integer

            iIdx = 0

            dgvUS.Columns.Insert(iIdx, Me.pSelected)
            dgvUS.Columns("pSelected").DisplayIndex = iIdx
            dgvUS.Columns("pSelected").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pCustomer)
            dgvUS.Columns("pCustomer").DisplayIndex = iIdx
            dgvUS.Columns("pCustomer").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pDetails)
            dgvUS.Columns("pDetails").DisplayIndex = iIdx
            dgvUS.Columns("pDetails").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pSelectCustomerInvoice)
            dgvUS.Columns("pSelectCustomerInvoice").DisplayIndex = iIdx
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pDate)
            dgvUS.Columns("pDate").DisplayIndex = iIdx
            dgvUS.Columns("pDate").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pAmount)
            dgvUS.Columns("pAmount").DisplayIndex = iIdx
            dgvUS.Columns("pAmount").DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleRight
            dgvUS.Columns("pAmount").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pName)
            dgvUS.Columns("pName").DisplayIndex = iIdx
            dgvUS.Columns("pName").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pPayment)
            dgvUS.Columns("pPayment").DisplayIndex = iIdx
            dgvUS.Columns("pPayment").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pCompany)
            dgvUS.Columns("pCompany").DisplayIndex = iIdx
            dgvUS.Columns("pCompany").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pType)
            dgvUS.Columns("pType").DisplayIndex = iIdx
            dgvUS.Columns("pType").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dgvUS.Columns.Insert(iIdx, Me.pDescription)
            dgvUS.Columns("pDescription").DisplayIndex = iIdx
            dgvUS.Columns("pDescription").SortMode = DataGridViewColumnSortMode.Automatic
            iIdx = iIdx + 1

            dataUpdatedUS()
        End If
    End Sub

This is a snippet of the custom object that is in the collection

Public Class ItemXact01
    Public Property FirstName As String
    Public Property LastName As String
    Public Property Company As String
    Public Property Type As String
    Public Property Description As String
    Public Property RefNumber As String
    Public Property DownloadID As String
    Public Property Selected As Boolean
    Public Property RequestID As Integer

    ...

    Public ReadOnly Property pCompany As String
        Get
            pCompany = Company
        End Get
    End Property

    Public ReadOnly Property pType As String
        Get
            pType = Type
        End Get
    End Property

    Public ReadOnly Property pDescription As String
        Get
            pDescription = Description
        End Get
    End Property

    Public ReadOnly Property pSelected As Boolean
        Get
            pSelected = Selected
        End Get
    End Property

...

The data is put into place with this code

    Private Sub dataUpdateDGV(ByRef dgv As DataGridView, ByRef myCollection As Collection)
        myMain.Log("dataUpdatedDGV: 001 :" & dgv.RowCount & ":" & myCollection.Count & ":")

' for some reason the not equal to does not show in the next line

        If dgv.RowCount  myCollection.Count Then
            myMain.Log("dataUpdatedDGV: 002")

            dgv.DataSource = Nothing
            If myCollection.Count > 0 Then
                myMain.Log("dataUpdatedDGV: 003")

                dgv.DataSource = myCollection
            End If
        End If

        myMain.Log("dataUpdatedDGV: 004")

        dgv.Invalidate()
        dgv.Update()
        dgv.Refresh()

        myMain.Log("dataUpdatedDGV: OUT")
    End Sub

Solution 1

If I remember correctly you can put a binding source between you collection and the datagridview and the binding source will provide a bunch of functionality. I think it allows you to sort as well. This is all just off the top of my head as I can't test it right now.

Solution 2

The key thing here is that the DataGridView isn't responsible for sorting; the underlying data-source (i.e. .DataSource of the DataSource) is.

you could implement something like this SortableBindingList (for Windows.Forms) http://www.martinwilley.com/net/code/forms/sortablebindinglist.html

Comments

[Bodger]

Thank you for your response, but I don't need it custom sorted, I just want it sorted by the column selected. Nothing happens when I click on the column header.

[Bodger]

I found a SortableBindingList class out in the ether and it works.

[The Dag]

You're right, but it must be said it is a disastrous design. How a grid is sorted is clearly a presentation matter and should be handled by the control. And frankly it's difficult to see why it would be hard to do, so long as the bound values in a column are the same type (usually the case) and implement IComparable (as all the basic datatypes do). One side-effect of this winforms approach is that you can't bind a list to multiple views, because the datasource tracks order and selected item and so on. Picture a view with lots of amounts and a dropdown list of currencies associated with each.

[Nick Wallace]

The sorting applied to a particular grid is in the DataGridView. The method for actual sorting is in the DataSource.