擴展 GridView 控件 - 無數據時顯示標題列

Page Code

 <gvExtrend:GridViewEmptyHeader ID="gvEmptyHeader" runat="server" AutoGenerateColumns="False"
            EmptyShowHeader="True" EmptyDataText="Empty Data" AllowPaging="True" 
            DataKeyNames="ProductID" DataSourceID="SqlDataSource1">
            <Columns>
                <asp:BoundField DataField="ProductID" HeaderText="ProductID" ReadOnly="True" 
                    SortExpression="ProductID" />
                <asp:BoundField DataField="ProductName" HeaderText="ProductName" 
                    SortExpression="ProductName" />
                <asp:BoundField DataField="SupplierID" HeaderText="SupplierID" 
                    SortExpression="SupplierID" />
            </Columns>
        </gvExtrend:GridViewEmptyHeader>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="Data Source=./sqlexpress;Initial Catalog=Northwind;Integrated Security=True" 
            ProviderName="System.Data.SqlClient" 
            SelectCommand="SELECT [ProductID], [ProductName], [SupplierID] FROM [Alphabetical list of products] WHERE ([CategoryID] = @CategoryID)">
            <SelectParameters>
                <asp:Parameter DefaultValue="99999" Name="CategoryID" Type="Int32" />
            </SelectParameters>
        </asp:SqlDataSource>

Web.Config 添加註冊Tag

<pages>
   <controls>
         <add tagPrefix="gvExtrend" namespace="GridViewExtrend" assembly="GridViewExtrend"/>
   </controls>
</pages>

GridViewExtrend Source

namespace GridViewExtrend
    {
        using System.Web.UI.WebControls;
        using System;
        using System.Collections.Generic;
        using System.ComponentModel;
        using System.Text;
        using System.Web.UI;
        using System.Drawing;
        using System.Collections;

        [Description("GridViewEmptyHeader"), ToolboxData("<{0}:GvEmptyHeader runat=server><{0}:GvEmptyHeader>")]
        public class GridViewEmptyHeader : GridView
        {
            private Boolean fEmptyShowHeader = true;

            /// <summary>
            /// 無數據時是否顯示字段標題
            /// </summary>
            public Boolean EmptyShowHeader
            {
               get
               {
                     return fEmptyShowHeader;
               }
                set
               {
                     fEmptyShowHeader = value;
                }
          }
    
           /// <summary>
            /// 建立子控件
            /// </summary>
            /// <param name="dataSource"></param>
            /// <param name="dataBinding"></param>
            /// <returns>建立的數據列數目</returns>
            protected override int CreateChildControls(IEnumerable dataSource, bool dataBinding)
             {
                Int32 rowCount;
                Table table = new Table();
    
                rowCount = base.CreateChildControls(dataSource, dataBinding);
    
                if (this.fEmptyShowHeader && (rowCount == 0))
                 {
                    table = CreateEmptyTable();
                    Controls.Clear();
                    Controls.Add(table);
                }
    
                return rowCount;
            }
    
            private Table CreateEmptyTable()
             {
                Table table = new Table();
                GridViewRow gridViewRow;
                TableCell cell = new TableCell();
                Int32 count;
                GridViewRowEventArgs e;
    
                table = base.CreateChildTable();
                count = this.Columns.Count - 1;
    
                //Create Title Columns
                gridViewRow = base.CreateRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal);
                DataControlField[] fields = new DataControlField[count + 1];
                this.Columns.CopyTo(fields, 0);
                this.InitializeRow(gridViewRow, fields);
                e = new GridViewRowEventArgs(gridViewRow);
                this.OnRowCreated(e);
                table.Rows.Add(gridViewRow);
    
                //Create Empty DataColumns
                gridViewRow = new GridViewRow(-1, -1, DataControlRowType.DataRow, DataControlRowState.Normal);
                cell.ColumnSpan = fields.Length;
                cell.Width = Unit.Percentage(100);
                cell.Text = this.EmptyDataText;
                cell.HorizontalAlign = HorizontalAlign.Center;
                gridViewRow.Cells.Add(cell);
                table.Rows.Add(gridViewRow);
    
                return table;
            }
        }
    }