Can't edit a gridview inside repeater-getting null reference error

Question

User646364117 posted

gvContent is inside a repeater. Getting null reference error in 1st line

    Protected Sub gvContent_RowUpdating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewUpdateEventArgs)

        Dim row As GridViewRow = gvContent.Rows(e.RowIndex)

<asp:Repeater ID="rptBlock" runat="server">
                <ItemTemplate>

                    <asp:Label ID="Label1" runat="server" Text="Block: " Style="font-weight: bold; color: black; background-color: #5DBCD2;" />
                    <asp:Label ID="lblBlock" runat="server" Text='<%# Eval("name") %>' Style="font-weight: bold; color: black; background-color: #5DBCD2; padding-left: 3px; padding-right: 3px;" />
                    <asp:Literal ID="Literal2" runat="server"> is assigned to these templates: </asp:Literal>
                    <asp:HiddenField ID="hfBlockID" runat="server" Value='<%# Eval("id") %>'></asp:HiddenField>
                    <asp:HiddenField ID="hfBlockType" runat="server" Value='<%# Eval("blocktype") %>'></asp:HiddenField>
                    <asp:TextBox ID="txtTemplateList" runat="server" Text='<%# Eval("TemplateList") %>' Visible="True" Style="font-weight: bold;" TextMode="MultiLine" />
                    <asp:ImageButton ID="btnAssignTemplates" runat="server" src="images/addnew_21.png" CommandName="AssignTemplates" />


                    <asp:Panel ID="Panel1" runat="server">
                        <h3>Assign Block To Templates</h3>
                        <asp:ListBox ID="lstTemplate" Width="250" SelectionMode="Multiple" runat="server"></asp:ListBox>
                        <asp:HiddenField ID="txtTemplateIDList" runat="server" Value='<%# Eval("templateidList") %>'></asp:HiddenField>
                        <asp:HiddenField ID="blockID" runat="server" Value='<%# Eval("id") %>'></asp:HiddenField>
                        <asp:ImageButton ID="btnSaveAssignedTemplates" runat="server" src="images/save_20.png" CommandName="SaveTemplates" />
                        <asp:ImageButton ID="btnCancelAssignTemplates" runat="server" src="images/cancel_20.png" CommandName="CancelAssignTemplates" />
                    </asp:Panel>
                    <asp:GridView ID="gvContent"
                        AutoGenerateColumns="false"
                        runat="server"
                        OnRowEditing="gvContent_RowEditing"
                        OnRowUpdating="gvContent_RowUpdating"
                        OnRowCancelingEdit="gvContent_RowCancelingEdit"
                        OnRowDataBound="gvContent_OnRowDataBound">


                        <Columns>
                            <asp:TemplateField HeaderText="Short Text" Visible="false">
                                <ItemTemplate >
                                    <asp:TextBox ID="txt_id" runat="server" Value='<%#Eval("id") %>'></asp:TextBox>
                                </ItemTemplate>

                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Short Text">
                                <ItemTemplate >
                                    <asp:Label ID="lbl_shorttext" runat="server" Text='<%#Eval("shorttext") %>'></asp:Label>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:TextBox ID="txt_shorttext" runat="server" Text='<%#Eval("shorttext") %>'></asp:TextBox>
                                </EditItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Long Text">
                                <ItemTemplate>
                                    <asp:Label ID="lbl_longtext" runat="server" Text='<%#Eval("longtext") %>'></asp:Label>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:TextBox ID="txt_longtext" runat="server" Text='<%#Eval("longtext") %>' ></asp:TextBox>
                                </EditItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:ImageButton ID="btn_Edit" runat="server" CommandName="Edit" src="images/edit_20.png" />
                               
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:ImageButton ID="btn_Update" runat="server" CommandName="Update" src="images/save_20.png" />
                                  
                                    <asp:ImageButton ID="btn_Cancel" runat="server" CommandName="Cancel" src="images/cancel_20.png" />
                                   
                                </EditItemTemplate>
                            </asp:TemplateField>

                        </Columns>



                    </asp:GridView>

                </ItemTemplate>
                <SeparatorTemplate>
                    <br />
                    <hr />
                    <br />
                </SeparatorTemplate>
            </asp:Repeater>

Answer 1

User283571144 posted

Hi sg48asp,

Since you nested the grid view control in Repeater, you cannot directly fetch the grid view by calling the ID of it.A feasible way is to cast the sender of the event "gvContent_RowUpdating" to "GridView" because the sender argument is always the control that triggered the event. Here I made an demo based on the code you gave to demostrate how to fetch the GridViewRow.

.Aspx Page:

<asp:Repeater ID="rptBlock" runat="server" OnItemDataBound="rptBlock_ItemDataBound">

                 <ItemTemplate>

                    <asp:Label ID="Label1" runat="server" Text="Block: "/>
                    <asp:Label ID="Label2" runat="server" Text='<% #Container.ItemIndex %>' />
                    <asp:GridView ID="gvContent"
                        AutoGenerateColumns="false"
                        runat="server"
                        OnRowEditing="gvContent_RowEditing"
                        OnRowCancelingEdit="gvContent_RowCancelingEdit"
                        OnRowUpdating="gvContent_RowUpdating"
                        >
                        <Columns>
                            <asp:TemplateField HeaderText="Text ID" Visible="false">
                                <ItemTemplate >
                                    <asp:TextBox ID="txt_id" runat="server" Value='<%#Eval("id") %>'></asp:TextBox>
                                </ItemTemplate>

                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Row Num">
                                <ItemTemplate >
                                    <asp:Label ID="lbl_rowNum" runat="server" Text='<%#Eval("rowNum") %>'></asp:Label>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:TextBox ID="txt_rowNum" runat="server" Text='<%#Eval("rowNum") %>'></asp:TextBox>
                                </EditItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Short Text">
                                <ItemTemplate >
                                    <asp:Label ID="lbl_shorttext" runat="server" Text='<%#Eval("shorttext") %>'></asp:Label>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:TextBox ID="txt_shorttext" runat="server" Text='<%#Eval("shorttext") %>'></asp:TextBox>
                                </EditItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Long Text">
                                <ItemTemplate>
                                    <asp:Label ID="lbl_longtext" runat="server" Text='<%#Eval("longtext") %>'></asp:Label>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:TextBox ID="txt_longtext" runat="server" Text='<%#Eval("longtext") %>'></asp:TextBox>
                                </EditItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:Button ID="btn_Edit" runat="server" CommandArgument='<%# Container.DataItemIndex %>' CommandName="Edit" Text="Edit"/>
                               
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:Button ID="btn_Update" runat="server" CommandArgument='<%# Container.DataItemIndex %>' CommandName="Update" Text="Update"/>
                                 
                                    <asp:Button ID="btn_Cancel" runat="server" CommandName="Cancel" Text="Cancel"/>
                                   
                                </EditItemTemplate>
                            </asp:TemplateField>

                        </Columns>
                    </asp:GridView>

                </ItemTemplate>
                <SeparatorTemplate>
                    <br />
                    <hr />
                    <br />
                </SeparatorTemplate>
            </asp:Repeater>

Code-behind:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
        If Not IsPostBack Then
            BindRepeater()
        End If
    End Sub

    Private Sub BindRepeater()
        Dim dt As DataTable = New DataTable()
        dt.Columns.Add("rowNum", GetType(Integer))

        For i As Integer = 0 To 3 - 1
            dt.Rows.Add(i)
        Next

        rptBlock.DataSource = dt
        rptBlock.DataBind()
    End Sub

    Private Sub BindGridViewByRowNum(ByVal rowNum As Integer, ByVal gd As GridView)
        Dim dt As DataTable = New DataTable()
        dt.Columns.Add("id", GetType(Integer))
        dt.Columns.Add("rowNum", GetType(Integer))
        dt.Columns.Add("shorttext", GetType(String))
        dt.Columns.Add("longtext", GetType(String))

        For i As Integer = 0 To 3 - 1
            dt.Rows.Add(i, rowNum, "shortext-" & i & "(rowNum-" & rowNum & ")", "longtext-" & i & "(rowNum-" & rowNum & ")")
        Next

        gd.DataSource = dt
        gd.DataBind()
    End Sub

    Protected Sub rptBlock_ItemDataBound(ByVal sender As Object, ByVal e As RepeaterItemEventArgs)
        If e.Item.ItemType = ListItemType.Item OrElse e.Item.ItemType = ListItemType.AlternatingItem Then
            Dim gd As GridView = CType(e.Item.FindControl("gvContent"), GridView)
            Dim lbl As Label = CType(e.Item.FindControl("Label2"), Label)
            Dim rowNum As Integer = Convert.ToInt32(lbl.Text)
            BindGridViewByRowNum(rowNum, gd)
        End If
    End Sub

    Protected Sub gvContent_RowEditing(ByVal sender As Object, ByVal e As GridViewEditEventArgs)
        Dim gd As GridView = CType(sender, GridView)
        gd.EditIndex = e.NewEditIndex
        Dim row As GridViewRow = gd.Rows(e.NewEditIndex)
        Dim rowNum As Integer = Convert.ToInt32((CType(row.FindControl("lbl_rowNum"), Label)).Text)
        BindGridViewByRowNum(rowNum, gd)
    End Sub

    Protected Sub gvContent_RowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
        Dim gd As GridView = CType(sender, GridView)
        gd.EditIndex = -1
        BindRepeater()
    End Sub

    Protected Sub gvContent_RowUpdating(ByVal sender As Object, ByVal e As GridViewUpdateEventArgs)
        Dim gd As GridView = CType(sender, GridView)
        Dim row As GridViewRow = gd.Rows(e.RowIndex)
        Dim rowNum As String = (CType(row.FindControl("txt_rowNum"), TextBox)).Text
        Dim shorttext As String = (CType(row.FindControl("txt_shorttext"), TextBox)).Text
        Dim longtext As String = (CType(row.FindControl("txt_longtext"), TextBox)).Text
        Page.ClientScript.RegisterClientScriptBlock([GetType](), "js", "<script>alert('you have select row: rowNum = " & rowNum & ", shorttext = " & shorttext & ", longtext = " & longtext & "');</script>")
        gd.EditIndex = -1
        BindRepeater()
    End Sub

Result:

Best Regards,

Brando