Question

我正在尝试反序列化一个主要包含无关信息的XML文档。我创建的类反映了我试图从文档中选择的信息。

当我实际进行反序列化时，反序列化似乎是成功的，但CraigslistChannel和CraigslistItem变量总是最终为null，即使文档clear中包含这些元素。

我试图反序列化的XML文档可以在这里找到：https://limaohio.craigslist.org/search/ctd?format=rss&s=25

看起来像这样：

function handler (event, context, callback) {
  context.callbackWaitsForEmptyEventLoop = false // Add this line
}

这是我的代码：

<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF
 xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
 xmlns="http://purl.org/rss/1.0/"
 xmlns:enc="http://purl.oclc.org/net/rss_2.0/enc#"
 xmlns:ev="http://purl.org/rss/1.0/modules/event/"
 xmlns:content="http://purl.org/rss/1.0/modules/content/"
 xmlns:dcterms="http://purl.org/dc/terms/"
 xmlns:syn="http://purl.org/rss/1.0/modules/syndication/"
 xmlns:dc="http://purl.org/dc/elements/1.1/"
 xmlns:taxo="http://purl.org/rss/1.0/modules/taxonomy/"
 xmlns:admin="http://webns.net/mvcb/"
>

<channel rdf:about="https://sfbay.craigslist.org/search/sfc/ctd?format=rss">
<title>craigslist SF bay area | cars &#x26; trucks - by dealer search </title>
<link>https://sfbay.craigslist.org/search/sfc/ctd</link>
<description></description>
<dc:language>en-us</dc:language>
<dc:rights>copyright 2016 craiglist</dc:rights>
<dc:publisher>robot@craigslist.org</dc:publisher>
<dc:creator>robot@craigslist.org</dc:creator>
<dc:source>https://sfbay.craigslist.org/search/sfc/ctd?format=rss</dc:source>
<dc:title>craigslist SF bay area | cars &#x26; trucks - by dealer search </dc:title>
<dc:type>Collection</dc:type>
<syn:updateBase>2016-08-29T07:55:51-07:00</syn:updateBase>
<syn:updateFrequency>1</syn:updateFrequency>
<syn:updatePeriod>hourly</syn:updatePeriod>
<items>
 <rdf:Seq>
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755852598.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755847263.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755845763.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755841763.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755839975.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755836851.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755833170.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755831622.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755807313.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755759606.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755718561.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755713440.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755710804.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755708355.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755706051.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755706053.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755689225.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755671023.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755669710.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755668546.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755667302.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755666084.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755664804.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755663619.html" />
  <rdf:li rdf:resource="http://sfbay.craigslist.org/sfc/ctd/5755662504.html" />
 </rdf:Seq>
</items>
</channel>
<item rdf:about="http://sfbay.craigslist.org/sfc/ctd/5755852598.html">
<title><![CDATA[2013 *Ford* *Mustang* *2dr Coupe* -$26,899 (Certified Pre-Owned, Financing Available) &#x0024;26899]]></title>
<link>http://sfbay.craigslist.org/sfc/ctd/5755852598.html</link>
<description><![CDATA[*2013* *Ford* *Mustang* *2dr Coupe* - $26,899* (2013* *Ford* *Mustang* *2dr Coupe*) 
Phone: 
 <a href="/fb/sfo/ctd/5755852598" class="showcontact" title="click to show contact info">show contact info</a>

Price: $26,899 
Vehicle Information Overview 
Year: 2013 
Make: Ford 
Model: Mustang 
Trim: 2dr Coupe 
VIN: 1ZVBP8CF0D5271908 
Mileage: 15500 
B [...]]]></description>
<dc:date>2016-08-29T06:53:28-07:00</dc:date>
<dc:language>en-us</dc:language>
<dc:rights>copyright 2016 craiglist</dc:rights>
<dc:source>http://sfbay.craigslist.org/sfc/ctd/5755852598.html</dc:source>
<dc:title><![CDATA[2013 *Ford* *Mustang* *2dr Coupe* -$26,899 (Certified Pre-Owned, Financing Available) &#x0024;26899]]></dc:title>
<dc:type>text</dc:type>
<enc:enclosure resource="https://images.craigslist.org/00404_h6HxiFEMymk_300x300.jpg" type="image/jpeg"/>
<dcterms:issued>2016-08-29T06:53:28-07:00</dcterms:issued>
</item>
</rdf:RDF>

最重要的是，这里是我尝试反序列化的类：

String requestURL = "https://limaohio.craigslist.org/search/ctd?format=rss&s=25";
IHttpWebResponse response = (new HttpRequesterWrapper(4000)).GetWebResponse(requestURL);
if (!String.IsNullOrEmpty(response.HTML))
{
    XmlSerializer serializer = new XmlSerializer(typeof(CraigslistRDF));
    using (TextReader sr = new StringReader(response.HTML))
    {
        CraigslistRDF rss = (CraigslistRDF)serializer.Deserialize(sr);
        if (rss != null && rss.Channel != null)
        {
            var a = 1;
        }
    }
}

有没有人知道为什么CraigslistChannel和CraigslistItem属性总是为空？

非常感谢任何帮助。

Answer 1

因为您的channel和item元素具有命名空间。默认命名空间在根元素中声明为http://purl.org/rss/1.0/，因此请更改您的属性以匹配：

[XmlRoot(ElementName = "RDF", Namespace = "http://www.w3.org/1999/02/22-rdf-syntax-ns#")]
public class CraigslistRDF
{
    [XmlElement("channel", Namespace = "http://purl.org/rss/1.0/")]
    public CraigslistChannel Channel;

    [XmlElement("item", Namespace = "http://purl.org/rss/1.0/")]
    public CraigslistItem[] Items;
}

另外，[XmlRoot("item")]和[XmlRoot("channel")]属性未被使用且可以删除（这些类不会被用作根目录）。

Answer 2

试试xml linq

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Xml.Linq;

namespace ConsoleApplication1
{
    class Program
    {
        const string FILEMNAME = @"c:\temp\test.xml";
        static void Main(string[] args)
        {
            XDocument doc = XDocument.Load(FILEMNAME);
            XElement rdf = (XElement)doc.FirstNode;
            XNamespace rdfNs = rdf.GetNamespaceOfPrefix("rdf");
            XNamespace dcNs = rdf.GetNamespaceOfPrefix("dc");
            XNamespace defaultNs = rdf.GetDefaultNamespace();

            CraigslistRDF craigslistRDF = rdf.Elements(defaultNs + "channel").Select(x => new CraigslistRDF
            {
                Channel = new CraigslistChannel() {
                    About = (string)x.Attribute(rdfNs + "about"),
                    Description = (string)x.Elements(defaultNs + "description").FirstOrDefault(),
                    Link =  (string)x.Element(defaultNs + "link"),
                    Title =  (string)x.Element(defaultNs + "title")
                },

            }).FirstOrDefault();

            craigslistRDF.Items = rdf.Elements(defaultNs + "item").Select(x => new CraigslistItem()
            {
                About = (string)x.Attribute(rdfNs + "about"),
                Description = (string)x.Elements(defaultNs + "description").FirstOrDefault(),
                Link = (string)x.Element(defaultNs + "link"),
                Source = (string)x.Element(dcNs + "source"),
                Title = (string)x.Element(defaultNs + "title")
            }).ToArray();

        }
    }

    public class CraigslistRDF
    {
        public CraigslistChannel Channel { get; set; }
        public CraigslistItem[] Items { get; set; }
    }

    public class CraigslistChannel
    {
        public String About { get; set; }
        public String Title { get; set; }
        public String Link { get; set; }
        public String Description { get; set; }
    }

    public class CraigslistItem
    {
        public String About { get; set; }
        public String Title { get; set; }
        public String Link { get; set; }
        public String Description { get; set; }
        public String Source { get; set; }
    }
}

使用多个名称空间从XML反序列化select元素

2 个答案: