Is it possible to enable paging/sorting for a GridView which is databound in codebehind?_问答_开发者

I know that GridView can handle sorting and paging if I bind it to an ObjectDataSource that only needs to get the list of items in a SelectMethod. Since apparently all the ODS is doing is get the items I tried to bind the GridView directly to the collection of items.

I tried:

[aspx]

<asp:Button runat="server" OnClick="ItemsSearch" Text="Search" />
<asp:GridView runat="server" ID="ItemsGV"
    AllowPaging="true" 开发者_如何学JAVAAllowSorting="true" PageSize="4" />

[codebehind]

protected void ItemsSearch(object sender, EventArgs e)
{
    DataSet Items = new DataSet();
    Items.ReadXml(MapPath("Items.xml"));
    Session["items"] = Items;
    ItemsGV.DataSource = Session["items"];
    ItemsGV.DataBind();
}

The GridView is loaded with the data but if I click to sort or change page nothing happens.

Any ideea how to make this kind of binding work?

You have to add Event Handlers for when people click on those buttons.

Imagine this: the first time you load the page, all of the data you want goes into the GridView. ASP.NET realizes that you can only show X items on your first page, so it loads that into the control and sends it down to the client. Now, the user wants to see page 2 items. When they make this request, it gets to the server, but the server has lost all reference to page 2. It doesn't know what it should show.

You need to handle the events and tell it what to show. This will mean rebinding to the data and showing page 2 information.

After studying some tutorials I ended up with this solution:

[Default.aspx]

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="TemplateGridViewNoDataSourcePagingSorting.Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
  <title></title>
</head>
<body>
  <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true" />
    <asp:Button ID="Button1" runat="server" OnClick="ItemsSearch" Text="Search" />
    <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
      <ContentTemplate>
        <asp:GridView runat="server" ID="ItemsGV" Visible="false" 
          AllowPaging="true" AllowSorting="true" PageSize="4"
          OnPageIndexChanging="ItemsGV_PageIndexChanging" OnSorting="ItemsGV_Sorting">
        </asp:GridView>
      </ContentTemplate>
    </asp:UpdatePanel>
  </form>
</body>
</html>

[Default.aspx.cs]

using System;
using System.Data;
using System.Threading;
using System.Web.UI.WebControls;

namespace TemplateGridViewNoDataSourcePagingSorting
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                Thread.Sleep(3000); // simulate long response time
                var ItemsDataSet = new DataSet();
                ItemsDataSet.ReadXml(MapPath("Items.xml"));
                Session["items"] = ItemsDataSet.Tables[0];
                ViewState["sortingOrder"] = string.Empty;
            }
        }

        protected void ItemsGV_PageIndexChanging(object sender, GridViewPageEventArgs e)
        {
            ItemsGV.PageIndex = e.NewPageIndex;
            ItemsGV.DataSource = Session["items"];
            ItemsGV.DataBind();
        }

        protected void ItemsSearch(object sender, EventArgs e)
        {
            ItemsGV.Visible = true;
            DataBindGrid("", "");
        }

        private void DataBindGrid(string sortExpr, string sortOrder)
        {
            // if sorting expression had changed
            // set sort order to ascending
            if (sortExpr != (string)ViewState["sortingExpression"])
            {
                sortOrder = "asc";
                ViewState["sortingOrder"] = "asc";
            }
            ViewState["sortingExpression"] = sortExpr;

            var dt = Session["items"] as DataTable;
            if (dt != null)
            {
                DataView dv = dt.DefaultView;
                if (sortExpr != string.Empty)
                    dv.Sort = sortExpr + " " + sortOrder;
                ItemsGV.DataSource = dv;
                ItemsGV.DataBind();
            }
            else
            {
                ItemsGV.DataSource = null;
                ItemsGV.DataBind();
            }
        }

        protected void ItemsGV_Sorting(object sender, GridViewSortEventArgs e)
        {
            DataBindGrid(e.SortExpression, sortingOrder);
        }

        public string sortingOrder
        {
            get
            {
                if (ViewState["sortingOrder"].ToString() == "desc")
                    ViewState["sortingOrder"] = "asc";
                else
                    ViewState["sortingOrder"] = "desc";
                return ViewState["sortingOrder"].ToString();
            }
            set
            {
                ViewState["sortingOrder"] = value;
            }
        }
    }
}

[Items.xml]

<?xml version="1.0" encoding="utf-8" ?>
<Items>
  <Item>
    <ItemName>Item01</ItemName>
    <ItemDescription>Item01 Description</ItemDescription>
    <ItemPrice>2.50</ItemPrice>
    <ItemInStock>Y</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item02</ItemName>
    <ItemDescription>Item02 Description</ItemDescription>
    <ItemPrice>1.50</ItemPrice>
    <ItemInStock>Y</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item03</ItemName>
    <ItemDescription>Item03 Description</ItemDescription>
    <ItemPrice>3.50</ItemPrice>
    <ItemInStock>N</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item04</ItemName>
    <ItemDescription>Item04 Description</ItemDescription>
    <ItemPrice>5.00</ItemPrice>
    <ItemInStock>Y</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item05</ItemName>
    <ItemDescription>Item05 Description</ItemDescription>
    <ItemPrice>5.50</ItemPrice>
    <ItemInStock>N</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item06</ItemName>
    <ItemDescription>Item06 Description</ItemDescription>
    <ItemPrice>4.50</ItemPrice>
    <ItemInStock>N</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item07</ItemName>
    <ItemDescription>Item07 Description</ItemDescription>
    <ItemPrice>1.50</ItemPrice>
    <ItemInStock>Y</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item08</ItemName>
    <ItemDescription>Item08 Description</ItemDescription>
    <ItemPrice>7.50</ItemPrice>
    <ItemInStock>Y</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item09</ItemName>
    <ItemDescription>Item09 Description</ItemDescription>
    <ItemPrice>0.50</ItemPrice>
    <ItemInStock>N</ItemInStock>
  </Item>
  <Item>
    <ItemName>Item10</ItemName>
    <ItemDescription>Item10 Description</ItemDescription>
    <ItemPrice>3.50</ItemPrice>
    <ItemInStock>Y</ItemInStock>
  </Item>
</Items>