GridView Checkbox Column

Question

I used to have a class in 1.1 for the Datagrid that inherited from the DataGridColumn class. This allowed me to create a check box column with a client-side un/check-all box in the header. Then as I designed my grid I would just add my custom column.

I am currently on a project where I need similar functionality for the grid view, however, there does not seem to be a way to inherit or add functionality to a column.

So my question is, Is there a way to override a column? or Does this code already exist, in a reusable way?

Needs are simple: I would like for it to just register the JavaScript on the page and render a column of check boxes.

I have come across the 4guys sample already, but they have just put all the code into the code behind, I am looking for something a little less copy/paste.

Answer 1

I derived classes from System.Web.UI.WebControls.BoundField and .HyperLinkField You might be interested in inheriting from CheckBoxField class http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.checkboxfield.aspx

Answer 2

Could you just use a TemplateColumn with an ItemTemplate containing your CheckBox in your DataGrid Columns?

Something like:

<asp:DataGrid id="DG1" runat = "server" DataKeyField = "ID">
<Columns>
<asp:TemplateColumn HeaderText="ProductName">
<ItemTemplate>
<asp:CheckBox id="chkBox1" runat="server" 
Text =<%# DataBinder.Eval(Container.DataItem,"yourDataToBind") %>
checked='<%# DataBinder.Eval(Container.DataItem,"yourBoolToBind")  %>'>
</asp:CheckBox>
</ItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>

Answer 3

I inherited the BoundField and came up with this:

Page Code:

<%@ register tagprefix="CAC" namespace="UI.Controls" assembly="UI.Controls" %>    
<asp:gridview id="grdPrint" runat="server" autogeneratecolumns="False">
    <columns>
        <cac:checkallcolumn />
        <asp:boundfield datafield="CompanyName" headertext="Company Name" />
    </columns>
</asp:gridview>

And this is the control:

Imports system.Web.UI
Imports system.Web.UI.WebControls

Public Class CheckAllColumn
    Inherits BoundField

    Public Sub New()
        MyBase.New()
    End Sub

    Public ReadOnly Property SelectedIndexes() As List(Of Int32)
        Get
            Dim selectedIndexList As New List(Of Int32)
            Dim grdParent As GridView = CType(Me.Control, GridView)
            For Each item As GridViewRow In grdParent.Rows
                Dim chkBox As CheckBox = CType(item.FindControl("checkboxCol"), CheckBox)
                If ((Not (chkBox) Is Nothing) _
                            AndAlso chkBox.Checked) Then
                    selectedIndexList.Add(item.DataItemIndex)
                End If
            Next
            Return selectedIndexList
        End Get
    End Property

    Public ReadOnly Property SelectedDataKeys() As Object()
        Get
            Dim dataKeyList As ArrayList = New ArrayList
            Dim grdParent As GridView = CType(Me.Control, GridView)
            If (grdParent.DataKeys.Count > 0) Then
                For Each selectedIndex As Int32 In SelectedIndexes
                    Dim DataKey As Object = grdParent.DataKeys(selectedIndex).ToString
                    dataKeyList.Add(DataKey)
                Next
            End If
            Return CType(dataKeyList.ToArray(GetType(System.Object)), Object())
        End Get
    End Property

    Public Overrides Sub InitializeCell(ByVal cell As DataControlFieldCell, ByVal cellType As DataControlCellType, ByVal rowState As DataControlRowState, ByVal rowIndex As Integer)
        If cell Is Nothing Then
            Throw New ArgumentNullException("cell", "cell is null.")
        End If
        MyBase.InitializeCell(cell, cellType, rowState, rowIndex)
        If (cellType = DataControlCellType.Header) OrElse (cellType = DataControlCellType.DataCell) Then
            Dim checkbox As CheckBox = New CheckBox
            If cellType = DataControlCellType.Header Then
                checkbox.ID = "checkboxHead"
            Else
                checkbox.ID = "checkboxCol"
            End If
            cell.Controls.Add(checkbox)
        End If
    End Sub

    Public Shared Sub RegisterClientCheckEvents(ByVal pg As Page, ByVal formID As String)
        If pg Is Nothing Then
            Throw New ArgumentNullException("pg", "pg is null.")
        End If
        If formID Is Nothing OrElse formID.Length = 0 Then
            Throw New ArgumentException("formID is null or empty.", "formID")
        End If
        Dim strCol As String = GetCheckColScript()
        Dim strHead As String = GetCheckHeadScript()
        If Not pg.ClientScript.IsClientScriptBlockRegistered("clientScriptCheckAll") Then
            pg.ClientScript.RegisterClientScriptBlock(pg.GetType, "clientScriptCheckAll", strHead.Replace("[frmID]", formID))
        End If
        If Not pg.ClientScript.IsClientScriptBlockRegistered("clientScriptCheckChanged") Then
            pg.ClientScript.RegisterClientScriptBlock(pg.GetType, "clientScriptCheckChanged", strCol.Replace("[frmID]", formID))
        End If
        RegisterAttributes(pg)
    End Sub

    Private Shared Sub RegisterAttributes(ByVal ctrl As Control)
        For Each wc As Control In ctrl.Controls
            If wc.HasControls Then
                RegisterAttributes(wc)
            End If
            If TypeOf (wc) Is CheckBox Then
                Dim chk As CheckBox = DirectCast(wc, CheckBox)
                If Not chk Is Nothing AndAlso chk.ID = "checkboxCol" Then
                    chk.Attributes.Add("onclick", "CheckChanged()")
                ElseIf Not chk Is Nothing AndAlso chk.ID = "checkboxHead" Then
                    chk.Attributes.Add("onclick", "CheckAll(this)")
                End If
            End If
        Next
    End Sub

    Private Shared Function GetCheckColScript() As String
        Dim strScript As String
        strScript = " <script language=JavaScript>"
        strScript &= " function CheckAll( checkAllBox )"
        strScript &= " {"
        strScript &= " var frm = document.[frmID];"
        strScript &= "  var ChkState=checkAllBox.checked;"
        strScript &= "  for(i=0;i< frm.length;i++)"
        strScript &= "  {"
        strScript &= "         e=frm.elements[i];"
        strScript &= "        if(e.type=='checkbox' && e.name.indexOf('checkboxCol') != -1)"
        strScript &= "            e.checked= ChkState ;"
        strScript &= "  }"
        strScript &= " }"
        strScript &= "  </script>"
        Return strScript
    End Function

    Private Shared Function GetCheckHeadScript() As String
        Dim strScript As String
        strScript = "<script language=JavaScript>"
        strScript &= "function CheckChanged()"
        strScript &= "{"
        strScript &= "  var frm = document.[frmID];"
        strScript &= "  var boolAllChecked;"
        strScript &= "  boolAllChecked=true;"
        strScript &= "  for(i=0;i< frm.length;i++)"
        strScript &= "  {"
        strScript &= "    e=frm.elements[i];"
        strScript &= "  if ( e.type=='checkbox' && e.name.indexOf('checkboxCol') != -1 )"
        strScript &= "      if(e.checked== false)"
        strScript &= "      {"
        strScript &= "         boolAllChecked=false;"
        strScript &= "         break;"
        strScript &= "      }"
        strScript &= "  }"
        strScript &= "  for(i=0;i< frm.length;i++)"
        strScript &= "  {"
        strScript &= "    e=frm.elements[i];"
        strScript &= "    if ( e.type=='checkbox' && e.name.indexOf('checkboxHead') != -1 )"
        strScript &= "    {"
        strScript &= "      if( boolAllChecked==false)"
        strScript &= "         e.checked= false ;"
        strScript &= "      else"
        strScript &= "         e.checked= true;"
        strScript &= "      break;"
        strScript &= "    }"
        strScript &= "   }"
        strScript &= " }"
        strScript &= " </script>"
        Return strScript
    End Function
End Class

Answer 4

Hi Brian Schmitt, I like your idea. But when and where is the method "RegisterClientCheckEvents" be called?