Custom Gridview Control : The Official Microsoft ASP.NET Forums

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cartch

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Custom Gridview Control

Oct 12, 2006 06:56 PM|LINK

I am building a Custom Web control which inherits the gridview. I am doing this so I can add a defaultsortexpression for the gridview so I can set the sort order before any of the header links are clicked. I am connecting my custom gridview to an objectdatasoruce, which should allow support sorting, however, when I look at the page in design view, the custom gridview has a message saying that "There was an error rendering the control. The data source does not support sorting" I am posting my code below. I'd appreciate any assistance. Thanks in advance!

Custom Control Code in a file I have named CustGridView.vb

Imports Microsoft.VisualBasic


Namespace CustControls
    Public Class CustGridView
        Inherits System.Web.UI.WebControls.GridView


        <ComponentModel.Browsable(True)> _
        <ComponentModel.Description("Default Sort BLOCKED EXPRESSION")> _
        <ComponentModel.Category("Behavior")> _
        Public Property DefaultSortExpression() As String
            Get
                Dim TheDefaultSortExpression As String = CType(Me.ViewState("DefaultSortExpression"), String)
                If TheDefaultSortExpression Is DBNull.Value Then
                    Return String.Empty
                End If
                Return TheDefaultSortExpression
            End Get
            Set(ByVal value As String)
                Me.ViewState("DefaultSortExpression") = value
            End Set
        End Property


        <ComponentModel.Browsable(True)> _
        <ComponentModel.Description("Default Sort BLOCKED EXPRESSION")> _
        <ComponentModel.Category("Behavior")> _
        Public Property DefaultSortDirection() As SortDirection
            Get
                Dim TheDefaultSortDirection As Object = Me.ViewState("SortDirection")
                If TheDefaultSortDirection Is Nothing Then
                    Return WebControls.SortDirection.Ascending
                End If
                Return CType(TheDefaultSortDirection, SortDirection)
            End Get
            Set(ByVal value As SortDirection)


            End Set
        End Property


        Protected Overrides Function CreateDataSourceSelectArguments() As DataSourceSelectArguments
            Dim TheDataSourceSelectArguments As DataSourceSelectArguments = MyBase.CreateDataSourceSelectArguments
            If String.IsNullOrEmpty(TheDataSourceSelectArguments.SortExpression) And String.IsNullOrEmpty(Me.DefaultSortExpression) = False Then
                TheDataSourceSelectArguments.SortExpression = Me.DefaultSortExpression
                If Me.DefaultSortDirection = WebControls.SortDirection.Ascending Then
                    TheDataSourceSelectArguments.SortExpression += " ASC"
                Else
                    TheDataSourceSelectArguments.SortExpression += " DESC"
                End If
            End If
            Return TheDataSourceSelectArguments


        End Function


    End Class
End Namespace

.aspx code I am putting the custom gridview in named t.aspx

  <%@ Page Language="VB" MasterPageFile="~/Site.master" AutoEventWireup="false" CodeFile="t.aspx.vb" Inherits="t" title="Untitled Page" %>
<%@ Register namespace="CustControls" TagPrefix="scc" %>
<asp:Content ID="Content1" ContentPlaceHolderID="MainContent" Runat="Server">
<p>
    <scc:CustGridView runat="server" 
        ID="MyTest" 
        AllowPaging="true" 
        AllowSorting="true" 
        DefaultSortExpression="ColorDesc" 
        DefaultSortDirection="ascending" 
        AutoGenerateColumns="false" 
        DataSourceID="dsColors" DataKeyNames="ColorID" 
        EnableViewState="false" 
        PageSize="20" 
        PagerSettings-Mode="NextPreviousFirstLast" 
        PagerSettings-NextPageText="  Next  " 
        PagerSettings-PreviousPageText="Previous" 
        PagerStyle-ForeColor="#000000" 
        PagerSettings-Position="TopAndBottom">
    </scc:CustGridView>
</p>
    <asp:ObjectDataSource ID="dsColors" runat="server" SelectMethod="GetColors" TypeName="NJC_BLL">
    </asp:ObjectDataSource>
</asp:Content>