我正在构建的应用程序遇到异常问题，所以我要做的是用户可以查看他们创建的广告的预览，点击广告，这是一个动态链接，并且带到一个新页面，将更详细地显示广告。然后运行更多详细信息页面以检查查询字符串，将查询sting的参数传递给从数据库中提取正确详细信息的方法。这部分工作正常，但是当返回对象时，页面再次加载，调用相同的方法3次，但是使用null参数返回对不存在的对象的空引用。
我尝试重构代码，因此当页面加载时，除非搜索参数有效，否则不会从数据库中检索。当页面加载时，组件将无法工作，例如Image Carousel。
我已经尝试将参数硬编码到方法中，将完美地工作。只会加载一次。
我创建了两个新页面，它们不从主页面继承并使用完全相同的方法。工作得很好。我在两个不同的页面上尝试了这个方法，这些页面是从母版页继承的，同样的问题。
详细的Page.aspx
<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.Master" AutoEventWireup="true" CodeFile="DetailAdvert.aspx.cs" Inherits="Lenders.ie.DetailAdvert" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<div class="col-lg-9">
<div class="container">
<div class="row">
<!--Advert Image -->
<div class="container">
<div class="row">
<!-- Carosel goes here -->
<div class="row carousel-holder">
<div class="col-xs-12 col-sm-12 col-md-12 col-lg-10">
<div id="carousel-example-generic" class="carousel slide" data-ride="carousel">
<ol class="carousel-indicators">
<li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li>
<li data-target="#carousel-example-generic" data-slide-to="1"></li>
<li data-target="#carousel-example-generic" data-slide-to="2"></li>
</ol>
<div class="carousel-inner">
<div class="item active">
<img class="slide-image" id="Img1" runat="server" src="http://placehold.it/800x380" alt=""/>
</div>
<div class="item">
<img class="slide-image" id="Img2" runat="server" src="http://placehold.it/800x380" alt=""/>
</div>
<div class="item">
<img class="slide-image" id="Img3" runat="server" src="http://placehold.it/800x380" alt=""/>
</div>
</div>
<a class="left carousel-control" href="#carousel-example-generic" data-slide="prev">
<span class="glyphicon glyphicon-chevron-left"></span>
</a>
<a class="right carousel-control" href="#carousel-example-generic" data-slide="next">
<span class="glyphicon glyphicon-chevron-right"></span>
</a>
</div>
</div>
</div>
</div>
</div>
<!--User Details-->
<br />
<div class="container">
<div class="row">
<!-- Descriptin and profile view -->
<div class="col-xs-12 col-sm-6 col-md-6 col-lg-5">
<div class="well well-sm">
<div class="row">
<div class="col-xs-6 col-sm-6 col-md-6 col-lg-6">
<img src="" runat="server" id="imgProfilePic" alt="" class="img-rounded img-responsive" />
</div>
<div class="col-xs-4 col-sm-4 col-md-4 col-lg-4">
<h4>
<asp:Label ID="lblFristName" runat="server" Text=""></asp:Label>
<asp:Label ID="lblSecondName" runat="server" Text=""></asp:Label>
</h4>
<small><cite title="Location"><asp:Label ID="lblLocation" runat="server" Text=""></asp:Label> <i class="glyphicon glyphicon-map-marker">
</i></cite></small>
<p>
<i title="Email" class="glyphicon glyphicon-envelope"></i> <asp:Label ID="lblEmail" runat="server" Text=""></asp:Label>
<br />
<i title="Join Date" class="glyphicon glyphicon-user"></i> <asp:Label ID="lblJoinDate" runat="server" Text=""></asp:Label><br />
<i title="User Rating" class="glyphicon glyphicon-stats"> </i><asp:Label ID="lblUserRating" runat="server" Text=""></asp:Label><br />
<i title="Contact Number" class="glyphicon glyphicon-phone"> </i><asp:Label ID="lblContactNumber" runat="server" Text=""></asp:Label>
</p>
<!-- Split button -->
<asp:Button ID="btnMessage" runat="server" Text="Message" CssClass="btn btn-success" />
</div>
</div>
</div>
</div>
<!-- Description / Product Details-->
<div class="col-xs-12 col-sm-6 col-md-6 col-lg-5">
<div class="well well-sm">
<h4> Description: </h4>
<p>
<asp:Label ID="lblDesc" runat="server" Text=""></asp:Label>
</p>
</div>
</div>
</div>
</div>
<div class="container">
<div class="row">
<!-- Comment Section -->
<div class="col-xs-12 col-sm-12 col-md-12 col-lg-10">
<div class="well well-sm">
<h4>Comments</h4>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder2" runat="server">
</asp:Content>
详细的Aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using BLL;
using DataModels;
namespace Lenders.ie
{
public partial class DetailAdvert : System.Web.UI.Page
{
public Advert_User ReturnedUserAdvet = new Advert_User();
public BalAdvertManger BALMan = new BalAdvertManger();
protected void Page_Load(object sender, EventArgs e)
{
//Response.Cache.SetCacheability(HttpCacheability.NoCache);
//Response.ExpiresAbsolute = DateTime.Now.AddMonths(-1);
//GetData();
//PopulatePage();
//int UserID = Convert.ToInt32(Request.QueryString["UiD"]);
//int AdvertID = Convert.ToInt32(Request.QueryString["AdID"]);
if (!Page.IsPostBack)
{
GetData();
}
}
public void GetData()
{
//int UserID = 41;
//int AdvertID = 2;
int UserID = Convert.ToInt16(Request.QueryString["UiD"]);
int AdvertID = Convert.ToInt16(Request.QueryString["AdID"]);
if (UserID != 0 || AdvertID != 0)
{
ReturnedUserAdvet = BALMan.ReturnDetailedAdvert(UserID, AdvertID);
PopulatePage();
}
//int UserID = Convert.ToInt32(Request.QueryString["UiD"]);
//int AdvertID = Convert.ToInt32(Request.QueryString["AdID"]);
//int UserID = 41;
//int AdvertID = 2;
//ReturnedUserAdvet = BALMan.ReturnDetailedAdvert(UserID,AdvertID);
}
public void PopulatePage()
{
}
}
}
这是链接所在的位置并指向详细页面。
个人资料Page.aspx
<%@ Page Title="" Language="C#" EnableEventValidation="false" MasterPageFile="~/MasterPage.Master" AutoEventWireup="true" CodeBehind="ProfilePage.aspx.cs" Inherits="Lenders.ie.ProfilePage1" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<div class="container">
<div class="row">
<%-- Adverts View--%>
<asp:View ID="AdvertsView" runat="server">
<h2>Adverts</h2>
</asp:View>
<%-- View Adverts --%>
<asp:View ID="View_ViewAdverts" runat="server">
<h2>View Adverts</h2>
<div class="row">
<asp:Literal ID="Advert1" runat="server"></asp:Literal>
<asp:LinkButton ID="LinkButton1" OnClick="LinkButton1_Click" runat="server">LinkButton</asp:LinkButton>
</div>
</asp:View>
<%--There was three closing divs here--%>
<asp:View ID="MessageView" runat="server">
<h2>Messages</h2>
</asp:View>
</asp:MultiView>
</div>
</div>
</div>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder2" runat="server">
ProfilePage aspx.cs - 创建链接的方法
public void DisplayUserAdverts()
{
int UserID = Convert.ToInt32(Session["UserID"]);
int i = 0;
ListOfUserAdverts = BalAdvertManager.ReturnUserAdvert(UserID);
StringWriter stringWriter = new StringWriter();
using (HtmlTextWriter writer = new HtmlTextWriter(stringWriter))
{
foreach (Advert item in ListOfUserAdverts)
{
string ColDiv = "col-sm-4 col-lg-4 col-md-4";
string ThumbClass = "thumbnail";
string Image = "AdvertThumbnails/" + item.Img1.ToString();
string Caption = "caption";
string Link = "DetailAdvert.aspx/?AdID=" + item.AdvertID.ToString() + "&UiD=" + item.UserID.ToString();
Button btn = new Button();
writer.AddAttribute(HtmlTextWriterAttribute.Class, ColDiv);
writer.RenderBeginTag(HtmlTextWriterTag.Div);
writer.AddAttribute(HtmlTextWriterAttribute.Class, ThumbClass);
writer.RenderBeginTag(HtmlTextWriterTag.Div);
//writer.AddAttribute(HtmlTextWriterAttribute.Src, Image);
writer.AddAttribute(HtmlTextWriterAttribute.Href, Link);
writer.RenderBeginTag(HtmlTextWriterTag.A);
writer.AddAttribute(HtmlTextWriterAttribute.Src, Image);
writer.RenderBeginTag(HtmlTextWriterTag.Img);
writer.RenderEndTag();
writer.RenderEndTag();
writer.AddAttribute(HtmlTextWriterAttribute.Class, Caption);
writer.RenderBeginTag(HtmlTextWriterTag.Div);
//writer.AddAttribute(HtmlTextWriterAttribute.Src, Image);
//writer.RenderBeginTag(HtmlTextWriterTag.Div);
//writer.AddAttribute(HtmlTextWriterAttribute.Class, Caption);
writer.RenderBeginTag("h4");
writer.Write(item.Title.ToString());
writer.RenderEndTag();
writer.RenderBeginTag("p");
//Does Something
writer.Write(item.Desc.ToString().Substring(0, 50));
writer.Write("</br>");
writer.Write("Testing" + i.ToString());
writer.Write("</br>");
this.Controls.Add(btn);
writer.AddAttribute(HtmlTextWriterAttribute.Href, Link);
// writer.AddAttribute(HtmlTextWriterAttribute.Id);
writer.RenderBeginTag(HtmlTextWriterTag.A);
writer.Write("Link");
writer.RenderEndTag();
writer.RenderEndTag();
//writer.WriteBeginTag("p");
// // Does Something
//writer.WriteEndTag("p");
writer.RenderEndTag();
writer.RenderEndTag();
writer.RenderEndTag();
i++;
}
}
Advert1.Text = stringWriter.ToString();
}
Master Page.aspx
<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="MasterPage.master.cs" Inherits="Lenders.ie.MasterPage" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="">
<meta name="author" content="">
<title>Shop Homepage - Start Bootstrap Template</title>
<!-- Bootstrap Core Content -->
<link href="Content/bootstrap.min.css" rel="stylesheet">
<!-- Custom CSS -->
<link href="Content/shop-homepage.css" rel="stylesheet">
<!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
<!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
<!--[if lt IE 9]>
<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
<script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script>
<![endif]-->
</head>
<body>
<form id="form1" runat="server">
<!-- Navigation -->
<nav class="navbar navbar-inverse navbar-fixed-top" role="navigation">
<div class="container">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<%-- <a class="navbar-brand" href="www.google.com">
</a>--%>
</div>
<!-- Collect the nav links, forms, and other content for toggling -->
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav">
<li>
<asp:HyperLink ID="Home" runat="server">Home</asp:HyperLink>
</li>
<li>
<asp:HyperLink ID="Services" runat="server">Services</asp:HyperLink>
</li>
<li>
<asp:HyperLink ID="Contact" runat="server">Contact</asp:HyperLink>
</li>
<li>
<asp:HyperLink ID="Login" runat="server">Log In</asp:HyperLink>
</li>
</ul>
<div class="navbar-form navbar-right">
<div class="input-group input-sm">
<asp:TextBox ID="txtSearch" runat="server" CssClass="form-control form-control-sm " AutoPostBack="true"></asp:TextBox>
<span class="
</span>
</div>
</div>
</div>
<!-- /.navbar-collapse -->
</div>
<!-- /.container -->
</nav>
<div class="container">
<div class="row">
<div class="col-md-3">
<p class="lead">Shop Name</p>
<div class="list-group">
<asp:HyperLink ID="HyperLink1" CssClass="list-group-item" runat="server">Sports</asp:HyperLink>
<asp:HyperLink ID="HyperLink2" CssClass="list-group-item" runat="server">Hobbies</asp:HyperLink>
<asp:HyperLink ID="HyperLink3" CssClass="list-group-item" runat="server">Life Style</asp:HyperLink>
<asp:HyperLink ID="HyperLink4" CssClass="list-group-item" runat="server">Another Example</asp:HyperLink>
<asp:HyperLink ID="HyperLink5" CssClass="list-group-item" runat="server"> Blah </asp:HyperLink>
</div>
</div>
<%-- <div class="col-md-9">
<div class="row carousel-holder">
<div class="col-md-12">--%>
<asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
</asp:ContentPlaceHolder>
<asp:ContentPlaceHolder ID="ContentPlaceHolder2" runat="server">
</asp:ContentPlaceHolder>
</div>
</div>
<%-- </div>
</div>
</div>--%>
<div class="container">
<hr>
<!-- Footer -->
<footer>
<div class="row">
<div class="col-lg-12">
<p>Copyright © Your Website 2014</p>
</div>
</div>
</footer>
</div>
<!-- /.container -->
<!-- jQuery -->
<script src="js/jquery.js"></script>
<!-- Bootstrap Core JavaScript -->
<script src="js/bootstrap.min.js"></script>enter code here
</form>
</body>
</html>
Master Page.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Lenders.ie
{
public partial class MasterPage : System.Web.UI.MasterPage
{
protected void Page_Load(object sender, EventArgs e)
{
}
}
}