problem in Non-ASCII character search in XML file using linq to XML

StackOverflow https://stackoverflow.com/questions/4689795

문제

I am serching for an element in an XML file using following linq to xml query

XElement inspections = XElement.Load(new StreamReader( Server.MapPath(ResolveUrl(SelectInspection.InspectionFilePath)),Encoding.UTF8));

XElement inspection = (from elements in inspections.Elements("inspection")
                                       where elements.Element("inspectionid").Value == inspectionId.ToString()
                                       && elements.Element("databasename").Value == Encoding.UTF8.GetString(Request.ContentEncoding.GetBytes (Request.QueryString("DbName")))
                                       select elements).Single();

And my xml file is 

<?xml version="1.0" encoding="utf-8"?>
<inspections>
   <inspection>
    <inspectionid>8</inspectionid>
    <databasename>Åker</databasename>
    <exported>false</exported>
  </inspection>
 </inspections>

Despite the Request.QueryString("DbName") is equal to "Åker", query does not return any result.

도움이 되었습니까?

해결책

I've created a test web page with the following content:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebForm1" %>
<!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 runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
     <a href="WebForm1.aspx?DbName=Åker">Test</a><br />
    <asp:Label runat="server" ID="lblTest"></asp:Label>
    </form>
</body>
</html>

It's code-behind:

using System;
using System.Linq;
using System.Xml.Linq;

public partial class WebForm1 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        var xmlStr = "<?xml version=\"1.0\" encoding=\"utf-8\"?><inspections>   <inspection>    <inspectionid>8</inspectionid>    <databasename>Åker</databasename>    <exported>false</exported>  </inspection> </inspections>";
        var inspections = XElement.Parse(xmlStr);
        XElement inspection = (from elements in inspections.Elements("inspection")
                               where elements.Element("databasename").Value == Request.QueryString["DbName"]
                               select elements).FirstOrDefault();
        lblTest.Text = (inspection != null).ToString();

    }
}

When I click Test link, the lblTest text becomes True — so, query finds the element as expected.

In addition to Jon Skeet's solution which probably fixes the problem, you may pass wrong inspectionId parameter value resulting in failed search.

다른 팁

This looks wrong to me:

Encoding.UTF8.GetString(Request.ContentEncoding
                               .GetBytes(Request.QueryString("DbName")))

Why wouldn't Request.QueryString already have had appropriate decoding applied by ASP.NET?

I suggest you split the problem into two halves:

  • Make sure LINQ to XML can find the string: do that in a console app with hard-coded data
  • Make sure you can get the right query string: do that by logging the Unicode codepoints within Request.QueryString("DbName") as integers

I would expect you to just be able to use Request.QueryString("DbName") directly.

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