Custom Datagrid Implementation

Discussion in 'ASP .Net Building Controls' started by Brent Ritchie, Jun 28, 2006.

  1. Hello,

    I have been given the assignment of creating a custom datagrid for
    our company. The specs are pretty simple: 1) Use a webservice to
    populate and do other processing tasks.

    So far I made a test web service and derived it from a common
    interface. The Custom datagrid uses this interface to call methods of
    the webservice. This is ok. The problem I have is that when the
    datagrid is created, I cannot create any of the dynamic controls until
    I bind to the data and I cannot bind to the data until after the
    control has been created.

    Given this, how would I go about setting the viewstate / postdata
    manually on all of these controls.
     
    Brent Ritchie, Jun 28, 2006
    #1
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  2. I've decided to post the source of what I have now. I don't think that
    my previous description was clear after reading it again.

    Imports System.Text
    Imports System.ComponentModel
    Imports System.Web.UI
    Imports System.Web.UI.WebControls
    Imports IWebServices

    <ToolboxData("<{0}:FLSDataGrid runat=server></{0}:FLSDataGrid>")> _
    Public Class FLSDataGrid
    Inherits System.Web.UI.WebControls.DataGrid

    #Region "Public Methods"

    #Region "Constructors"

    Public Sub New()

    MyBase.New()
    Me.EnableViewState = True

    m_addrow = New DataGridItem(-1, -1, ListItemType.SelectedItem)

    Me.ViewState.Add("m_SortCriteria", "")
    Me.ViewState.Add("m_SortDirection", "ASC")
    Me.ViewState.Add("m_SearchEnabled", False)

    End Sub

    #End Region

    #End Region

    #Region "Public Properties"

    Public Property WebDataSource() As IDataWebService
    Get
    Return m_WebDataSource
    End Get
    Set(ByVal Value As IDataWebService)
    m_WebDataSource = Value
    MyBase.VirtualItemCount =
    m_WebDataSource.RetrieveRowCount()
    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))
    End Set
    End Property

    Private Property TextFieldsNeeded()
    Get
    If Not Me.ViewState.Item("m_TextFields") = Nothing Then
    Return Me.ViewState.Item("m_TextFields")
    Else
    Return 0
    End If
    End Get
    Set(ByVal Value)
    Me.ViewState.Item("m_TextFields") = Value
    End Set
    End Property

    Public Property SearchEnabled() As Boolean
    Get
    Return Me.ViewState.Item("m_SearchEnabled")
    End Get
    Set(ByVal Value As Boolean)
    Me.ViewState.Item("m_SearchEnabled") = Value
    End Set
    End Property

    Public Property SortCriteria() As String
    Get
    Return Me.ViewState.Item("m_SortCriteria")
    End Get
    Set(ByVal Value As String)
    Me.ViewState.Item("m_SortCriteria") = Value
    End Set
    End Property

    Public Property SortDirection() As String
    Get
    Return Me.ViewState.Item("m_SortDirection")
    End Get
    Set(ByVal Value As String)
    Me.ViewState.Item("m_SortDirection") = Value
    End Set
    End Property

    #End Region

    #Region "Protected Methods"

    Protected Overrides Sub Render(ByVal output As
    System.Web.UI.HtmlTextWriter)

    MyBase.Render(output)

    End Sub

    Protected Friend Overloads Sub OnPreRender(ByVal e As EventArgs)
    For Each c As Label In MyBase.Controls
    c.EnableViewState = False
    Next
    Me.CreateAndRegisterScripts()
    Me.CreateFooter()
    End Sub

    Protected Sub Sort(ByVal sender As Object, ByVal e As
    DataGridSortCommandEventArgs) Handles MyBase.SortCommand

    If SortCriteria = e.SortExpression Then
    If SortDirection = "ASC" Then
    SortDirection = "DESC"
    Else
    SortDirection = "ASC"
    End If
    Else
    SortCriteria = e.SortExpression
    SortDirection = "DESC"
    End If

    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    End Sub

    Protected Overloads Overrides Sub LoadViewState(ByVal savedState As
    Object)

    MyBase.LoadViewState(savedState)

    For Each str As String In Me.ViewState.Keys
    If str.StartsWith("txtAddRow") Then
    Page.Response.Write(Me.ViewState.Item(str))
    End If
    Next
    Me.CreateFooter()

    End Sub

    Protected Sub PageEvent(ByVal sender As Object, ByVal e As
    DataGridPageChangedEventArgs) Handles MyBase.PageIndexChanged

    MyBase.CurrentPageIndex = e.NewPageIndex
    If SearchEnabled = True Then

    Dim param As DataSet = New DataSet("Search Parameters")
    param.Tables.Add("Parameters")

    param.Tables("Parameters").Rows.Add(param.Tables("Parameters").NewRow())

    Dim editcolumn As Boolean = True
    Dim ii As Integer = 0

    For Each tc As TableCell In m_addrow.Cells

    If editcolumn Then

    editcolumn = False

    Else

    param.Tables("Parameters").Columns.Add("@" +
    DirectCast(MyBase.DataSource,
    DataSet).Tables(0).Columns(ii).ToString())
    param.Tables("Parameters").Rows(0).Item(ii) =
    Me.ViewState.Item(DirectCast(tc.Controls(0), TextBox).ID).ToString()
    ii += 1

    End If

    Next

    MyBase.DataSource = WebDataSource.RetrieveRecord(param)

    Else

    MyBase.DataSource =
    WebDataSource.RetrieveRowsSubset(e.NewPageIndex, MyBase.PageSize,
    Me.SortCriteria, Me.SortDirection)

    End If

    MyBase.DataBind()
    Me.CreateFooter()

    End Sub

    Protected Sub EditEvent(ByVal sender As Object, ByVal e As
    DataGridCommandEventArgs) Handles MyBase.EditCommand

    Me.EditItemIndex = e.Item.ItemIndex
    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    End Sub

    Protected Sub CancelEvent(ByVal sender As Object, ByVal e As
    DataGridCommandEventArgs) Handles MyBase.CancelCommand

    Me.EditItemIndex = -1
    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    End Sub

    Protected Sub UpdateEvent(ByVal sender As Object, ByVal e As
    DataGridCommandEventArgs) Handles MyBase.UpdateCommand

    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    Dim param As DataSet = New DataSet("Update Parameters")
    param.Tables.Add("Parameters")

    param.Tables("Parameters").Rows.Add(param.Tables("Parameters").NewRow())

    Dim editcolumn As Boolean = True
    Dim deletecolumn As Boolean = True
    Dim i As Integer = 0

    For Each tc As TableCell In e.Item.Cells
    If editcolumn Then
    editcolumn = False
    ElseIf deletecolumn Then
    deletecolumn = False
    Else

    Dim tb As TextBox = tc.Controls(0)
    param.Tables("Parameters").Columns.Add("@" +
    DirectCast(MyBase.DataSource, DataSet).Tables(0).Columns(i).ToString())
    param.Tables("Parameters").Rows(0).Item(i) = tb.Text
    i += 1

    End If
    Next

    Me.WebDataSource.UpdateRecord(param)
    Me.EditItemIndex = -1
    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    End Sub

    Protected Sub DeleteEvent(ByVal sender As Object, ByVal e As
    DataGridCommandEventArgs) Handles MyBase.DeleteCommand

    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    Dim param As DataSet = New DataSet("Update Parameters")
    param.Tables.Add("Parameters")

    param.Tables("Parameters").Rows.Add(param.Tables("Parameters").NewRow())

    Dim editcolumn As Boolean = True
    Dim deletecolumn As Boolean = True
    Dim i As Integer = 0

    For Each tc As TableCell In e.Item.Cells
    If editcolumn Then
    editcolumn = False
    ElseIf deletecolumn Then
    deletecolumn = False
    Else

    param.Tables("Parameters").Columns.Add("@" +
    DirectCast(MyBase.DataSource, DataSet).Tables(0).Columns(i).ToString())
    param.Tables("Parameters").Rows(0).Item(i) = tc.Text
    i += 1

    End If
    Next

    Me.WebDataSource.DeleteRecord(param)
    Me.EditItemIndex = -1
    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    End Sub

    Protected Sub AddRecordEvent(ByVal sender As Object, ByVal e As
    EventArgs)

    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    Dim param As DataSet = New DataSet("Update Parameters")
    param.Tables.Add("Parameters")

    param.Tables("Parameters").Rows.Add(param.Tables("Parameters").NewRow())

    Dim editcolumn As Boolean = True
    Dim i As Integer = 0

    For Each tc As TableCell In m_addrow.Cells
    If editcolumn Then
    editcolumn = False
    Else

    param.Tables("Parameters").Columns.Add("@" +
    DirectCast(MyBase.DataSource, DataSet).Tables(0).Columns(i).ToString())
    param.Tables("Parameters").Rows(0).Item(i) =
    Me.ViewState.Item(DirectCast(tc.Controls(0), TextBox).ID).ToString()
    i += 1

    End If
    Next

    Me.WebDataSource.InsertRecord(param)

    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    End Sub

    #End Region

    #Region "Private Methods"

    Private Sub FLSDataGrid_Init(ByVal sender As Object, ByVal e As
    System.EventArgs) Handles MyBase.Init

    Me.SetDefaultAttributes()
    Me.CreateDynamicControls()
    Me.CreateAndRegisterScripts()

    End Sub

    Private Sub SetDefaultAttributes()

    MyBase.AllowPaging = True
    MyBase.AllowCustomPaging = True
    MyBase.AllowSorting = True

    End Sub

    Private Sub CreateDynamicControls()

    Dim ecc As EditCommandColumn = New EditCommandColumn
    ecc.EditText = "Edit"
    ecc.CancelText = "Cancel"
    ecc.UpdateText = "Save"
    MyBase.Columns.Add(ecc)

    Dim bc As ButtonColumn = New ButtonColumn
    bc.ButtonType = ButtonColumnType.LinkButton
    bc.Text = "Delete"
    bc.CommandName = "Delete"

    MyBase.Columns.Add(bc)

    m_AddBtn = New LinkButton
    m_AddBtn.EnableViewState = True
    m_AddBtn.ID = "m_AddBtn"
    m_AddBtn.Text = "Add "
    m_AddBtn.Visible = True
    m_AddBtn.Attributes.Add("onClick", "ConfirmSave()")
    AddHandler m_AddBtn.Click, AddressOf Me.AddRecordEvent

    m_PlaceHolderAdd = New PlaceHolder
    m_PlaceHolderAdd.EnableViewState = False
    m_PlaceHolderAdd.Controls.Add(m_AddBtn)

    m_SearchBtn = New LinkButton
    m_SearchBtn.EnableViewState = False
    m_SearchBtn.ID = "m_SearchBtn"
    m_SearchBtn.Text = " Search"
    m_SearchBtn.Visible = True
    AddHandler m_SearchBtn.Click, AddressOf Me.SearchRecordEvent

    m_PlaceHolderSearch = New PlaceHolder
    m_PlaceHolderSearch.EnableViewState = True
    m_PlaceHolderSearch.Controls.Add(m_SearchBtn)

    End Sub

    Private Sub CreateAndRegisterScripts()

    Dim ConfirmSaveFunction As String = "<SCRIPT
    language='JavaScript'>function ConfirmSave() { if (confirm('Proceed
    with saving new record?')) return true; if (document.all &&
    window.event) event.returnValue = false; return false; }</SCRIPT>"
    Dim ConfirmDeleteFunction As String = "<SCRIPT
    language='JavaScript'>function ConfirmDelete() { if (confirm('Proceed
    with deleting record?')) return true; if (document.all && window.event)
    event.returnValue = false; return false; }</SCRIPT>"
    Page.RegisterClientScriptBlock("ConfirmSave",
    ConfirmSaveFunction)
    Page.RegisterClientScriptBlock("ConfirmDelete",
    ConfirmDeleteFunction)

    Dim DeleteConfirm As String = " <SCRIPT language='JavaScript'>
    " + _
    " for(i=0;i<document.links.length;i++) " + _
    " { " + _
    " var x = document.links; " + _
    " if(x.innerText==" + ControlChars.Quote + "Delete" +
    ControlChars.Quote + ") " + _
    " x.onclick = ConfirmDelete; " + _
    " continue; " + _
    " } " + _
    " </SCRIPT> "

    Page.RegisterStartupScript("DeleteConfirm", DeleteConfirm)

    End Sub

    Private Sub CreateFooter()

    Dim row As DataGridItem = New DataGridItem(-1, -1,
    ListItemType.SelectedItem)
    Dim arr As New ArrayList
    Dim firstControl As Boolean = True
    Dim i As Integer = 0

    For Each a As TableCell In MyBase.Items.Item(0).Cells
    If a.Controls.Count > 0 Then
    If firstControl Then

    Dim b As TableCell = New TableCell
    b.Controls.Add(m_PlaceHolderAdd)
    b.Controls.Add(m_PlaceHolderSearch)
    firstControl = False
    arr.Add(b)

    End If

    arr(0).ColumnSpan += 1

    Else

    Dim b As TableCell = New TableCell
    Dim c As TextBox = New TextBox
    c.ID = "txtAddRow" + i.ToString()
    If Not Page.IsPostBack Then
    Me.ViewState.Add(c.ID, "")
    End If
    c.Text = Me.ViewState.Item(c.ID)
    ' c.Text = Page.Request.Form.Item(c.ID)
    AddHandler c.TextChanged, AddressOf Me.TXT_Unload
    b.controls.Add(c)
    arr.Add(b)
    i += 1

    End If
    Next

    For Each a As TableCell In arr
    row.Cells.Add(a)
    Next


    MyBase.Controls(0).Controls.AddAt(MyBase.Controls(0).Controls.Count -
    2, row)
    m_addrow = row

    For Each dgi As DataGridItem In Me.Items
    For Each tc As System.Web.UI.WebControls.TableCell In
    dgi.Cells
    If Not tc.HasControls() Then
    tc.EnableViewState = False
    End If
    Next
    Next

    End Sub

    Private Sub TXT_Unload(ByVal sender As Object, ByVal e As
    System.EventArgs)

    Me.ViewState.Item(sender.id) = DirectCast(sender, TextBox).Text

    End Sub

    Private Sub SearchRecordEvent(ByVal sender As Object, ByVal e As
    System.EventArgs)

    Me.SearchEnabled = True
    Me.PageEvent(Me, New DataGridPageChangedEventArgs(Me,
    Me.CurrentPageIndex))

    End Sub

    #End Region

    #Region "Private Members"

    Private m_WebDataSource As IDataWebService
    Private m_AddBtn As LinkButton
    Private m_SearchBtn As LinkButton
    Private m_PlaceHolderAdd As PlaceHolder
    Private m_PlaceHolderSearch As PlaceHolder
    Private m_addrow As DataGridItem

    #End Region

    End Class
     
    Brent Ritchie, Jun 28, 2006
    #2
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  3. hi Brent, try overriding CreateControlHierarchy method of your base datagrid
    control. eg.

    Protected Overrides Sub CreateControlHierarchy ( _
    useDataSource As Boolean _
    )

    MyBase.CreateControlHierarchy(useDataSource) ' call the base method.
    ' now that the control hierarchy that is used
    ' to render the DataGrid is created, lets start creating our custom
    controls.
    ' Since the controls have already been created via our
    ' call to MyBase.CreateControlHierarchy(), you'd be looping
    ' through each row of the rendered datagrid to add
    ' your custom controls. Is this what you were after ?
    ' Further you asked about viewstate so :
    If (useDataSource) Then
    ' this means there is nothing in viewstate,
    ' since we are rendering the first time.
    Else
    ' no need to get data from the underlying datasource since
    ' we are going to be rendering from viewstate, probably a postback scenario
    End if
    End Sub

    Alessandro Zifiglio

     
    Alessandro Zifiglio, Jun 29, 2006
    #3
  4. After Some quick changes for testing. This is exactly what I needed.
    Just to be clear though, CreateControlHierarchy() happens after the
    binding but just before rendering? I've been looking through the
    Lifecycle examples and haven't seen this before.

    The reason I asked about viewstate is that the controls are being
    created so late that they don't have a chance for there viewstate or
    postback data to be restored automatically. I needed viewstate to be
    available after the controls are created to manually repopulate them.

    Thanks, this was what I needed.
     
    Brent Ritchie, Jun 29, 2006
    #4
  5. Brent, CreateControlHierarchy() is a method exposed by the datagrid, which
    is actually called from CreateChildControls() method with an argument of
    false, when its the first time the control is rendering. For all other
    times, CreateControlHierachy() is called with an argument of true from
    within the OnDataBinding method, so populating the data from the underlying
    datasource itself and not viewstate.

    Glad that helped you.
    Have a good day,
    Alessandro Zifiglio
     
    Alessandro Zifiglio, Jun 29, 2006
    #5
  6. oops :X
    I mean the exact opposite of what i stated earlier, so to avoid confusion
    this is exactly what i was trying to state :
    CreateControlHierarchy is called from within the CreateChildControls method
    with an argument of false when the control understands that it needs to
    populate the datacontrol from viewstate and not from the underlying
    datasource.

    while otherwise, CreateControlHierarchy() is called with an argument of true
    from onDataBinding() method and gets the data from the underlying
    datasource, which is triggered when the DataBind() method on your
    datacontrol is called.

    Apologies for confusion.
    Regards,
    Alessandro Zifiglio
     
    Alessandro Zifiglio, Jun 29, 2006
    #6
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