[Solved] Controls not retained in postback

[R N]

Hi,
I am creating a grid at runtime with viewstate enabled. I have a few columns that I am adding to this grid, again, at runtime. The item template and edit item template both have custom templates (that implement ITemplate and IBindableTemplate). And I have textboxes in these columns.

After I present the entire grid in edit mode, upon save, the textbox controls within these columns are "lost" upon postback. I am not able to retrieve them using findcontrol. The custom column definitions are there (but not the textboxes) and also available are the edit item count (basically the number of rows that the grid has in edit). Once I get past this challenge, my hope is to use the built-in functionality to extract the values that changed while editing (exported in HashTable format).

So my question is how can I get the controls from the item collection upon postback (without getting it lost)?

Thanks in advance for any help you can provide.

Let me know if you need to see any other code samples.

Thanks,
RN

    Protected Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
        'grid to display the header

        CreateHeaderGridStructure()

        'grid to display the details (w/o header)
        CreateDetailGridStructure()
        grdDetail.Rebind()

    End Sub

    Private Function CreateDetailGridStructure() As Boolean
        'get the column metadata to create the column input boxes.
        Dim drTemplateDetails As IDataReader
        Dim templateColumn As GridTemplateColumn

        grdDetail.MasterTableView.Columns.Clear()
        grdDetail.MasterTableView.DetailTables.Item(0).AutoGenerateColumns = False
        grdDetail.MasterTableView.ExpandCollapseColumn.ItemStyle.Width = Unit.Percentage(4)

        columnDefinitions = New System.Collections.Generic.List(Of GridColumnDefinition)
        drTemplateDetails = 'Get the data here
        While drTemplateDetails.Read()

            templateColumn = New GridTemplateColumn()
            templateColumn.DataField = <the column name>
            templateColumn.UniqueName = <the column name>            templateColumn.ItemTemplate = New GridDetailTemplate(<the column name>, Me.ClientID, ControlType.Label)

            If <if only viewable column with no edit> Then
                templateColumn.EditItemTemplate = New GridDetailTemplate(columnDefinition.Name, Me.ClientID, ControlType.Label)
                If columnDefinition.Type = GridColumnType.Hidden Then
                    templateColumn.Display = False
                End If
            Else
                'if the grid is in edit mode, then inEditMode = True
                If inEditMode Then
                    templateColumn.EditItemTemplate = New GridDetailTemplate(columnDefinition.Name, Me.ClientID, ControlType.PremiumTextBox)
                Else
                    templateColumn.EditItemTemplate = New GridDetailTemplate(columnDefinition.Name, Me.ClientID, ControlType.Label)
                End If
            End If
            grdDetail.MasterTableView.Columns.Add(templateColumn)
        End While

    End Function

    Private Sub grdDetail_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles grdDetail.PreRender


        'If using itemtemplate/edititemtemplate, then use the following to set the grid in edit mode.
        'todo: look to combine these following if logics into one
        If inEditMode Then
            If IsPostBack Then
                For Each item As GridItem In grdDetail.MasterTableView.Items
                    If TypeOf item Is GridEditableItem Then
                        Dim editableItem As GridEditableItem = CType(item, GridDataItem)
                        editableItem.Edit = True
                    End If
                Next
                grdDetail.Rebind()
            End If
        End If
End Function

Public Class GridDetailTemplate
    Implements ITemplate, System.Web.UI.IBindableTemplate

    Private controlID As String
    Private clientID As String
    Private type As ControlType

    'This is the only public constructor. Should also accept the kind of control that needs to be created
    Public Sub New(ByVal controlID As String, ByVal clientID As String, ByVal type As ControlType)
        MyBase.New()
        Me.controlID = controlID
        Me.clientID = clientID
        Me.type = type
    End Sub


    Public Function ExtractValues(ByVal container As Control) As Collections.Specialized.IOrderedDictionary Implements IBindableTemplate.ExtractValues
        Dim returnDictionary As Collections.Specialized.OrderedDictionary = New Collections.Specialized.OrderedDictionary()
        Select Case type
            Case ControlType.Label
                returnDictionary.Add(controlID, (DirectCast(((DirectCast(container, Telerik.Web.UI.GridDataItem)).FindControl(controlID)), Label)).Text)

            Case ControlType.PremiumTextBox
                returnDictionary.Add(controlID, (DirectCast(((DirectCast(container, Telerik.Web.UI.GridDataItem)).FindControl(controlID)), TextBox)).Text)
        End Select
        Return returnDictionary
    End Function

    Public Sub InstantiateIn(ByVal container As Control) Implements ITemplate.InstantiateIn
        'create the control that we want
        Dim control As New Control

        Select Case type
            Case ControlType.PremiumTextBox
                Dim txtBox As TextBox
                txtBox = New TextBox

                'attributes should be added in the item databound event to be consistent
                txtBox.Attributes.Add("onblur", "return validateInput(this);")
                'txtBox.Attributes.Add("onchange", "return testInput(this);")
                'txtBox.Attributes.Add("onchange", "return addNumbers('" + txtBox.ClientID + "')")
                'should be in the textbox control
                txtBox.MaxLength = 14
                txtBox.Width = Unit.Pixel(100)
                txtBox.Style.Add("text-align", "right")
                'txtBox.ClientEvents.OnValueChanged = "calculateTtl"

                'event handler to handle the databind event
                control = txtBox
                AddHandler control.DataBinding, AddressOf Me.TextBox1_DataBinding
         End Select

        'set the id to be an unique identifier for that row
        control.ID = controlID

        'add the control to the control collection
        container.Controls.Add(control)
End Function

    Public Sub TextBox1_DataBinding(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim textbox As TextBox = CType(sender, TextBox)
        Dim grid As GridDataItem = CType(textbox.NamingContainer, GridDataItem)
        Dim item1Value As String = DataBinder.Eval(grid.DataItem, controlID).ToString
        CType(grid.FindControl(controlID), TextBox).Text = item1Value
    End Sub
End Class

[R N]

I found the answer, I guess doing it in Pre_Render is too late in the page lifecycle. So I need to move that code into Page_Init.

http://www.telerik.com/help/aspnet-ajax/grdprogrammaticcreation.html

I have a button on the page that when clicked needs to trigger some changes to the grid (like edit/save, etc). Considering that those events can be captured only after the Page_Load event, how can I achieve it if the grid need to created in the Page_Init itself?

Thanks.

[R N]

Even following the instructions on creating an entire grid runtime, with template controls, I am still unable retrieve the textbox controls on postback.
This is what I am doing:
Page_Init has the function call to CreateGrid()

CreateGrid() creates a new radgrid, sets all the properties, adds the template columns. I add all the template columns after the properties have been set to the grid. And then the grid is added to the placeholder, to display the grid on the page. The page has viewstate enabled.

Please let me know what I may be missing.

Your assistance is greatly appreciated.

[Mira]

Hello RN,

I tried to replicate the issue which you described, but to no avail. Attached to this message, you will find the code which I used for testing. I hope you find it useful.

If the problem persists, please open a formal support ticket and attach a sample project demonstrating it. I will debug it locally and get back to you with my findings.

Best wishes,

Mira
the Telerik team

Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking system and vote to affect the priority of the items.

[Rodney King]

Thanks for the sample project. Please see support ticket #285241 for additional details on the issue that I am facing. I have attached my project to that ticket. Thanks!

[Mira]

Hi,

In this case, you can refer to the support ticket, which you have opened.
To avoid duplicate posts, we can continue our communication there.