LINQ查询问题

发布于 2024-11-09 02:55:54 字数 399 浏览 0 评论 0 原文

无法在 Feed 中获得任何结果。 feedXML 具有正确的数据。

XDocument feedXML = XDocument.Load(@"http://search.twitter.com/search.atom?q=twitter");

var feeds = from entry in feedXML.Descendants("entry")
            select new
            {
                PublicationDate = entry.Element("published").Value,
                Title = entry.Element("title").Value
            };

我缺少什么？

原文

Can't get any result in feeds.
feedXML has the correct data.

XDocument feedXML = XDocument.Load(@"http://search.twitter.com/search.atom?q=twitter");

var feeds = from entry in feedXML.Descendants("entry")
            select new
            {
                PublicationDate = entry.Element("published").Value,
                Title = entry.Element("title").Value
            };

What am I missing?

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巴黎盛开的樱花 2024-11-16 02:55:54

您需要指定命名空间：

// This is the default namespace within the feed, as specified
// xmlns="..." 
XNamespace ns = "http://www.w3.org/2005/Atom";

var feeds = from entry in feedXML.Descendants(ns + "entry")
            ...

与我使用过的一切其他 XML API 相比，LINQ to XML 中的命名空间处理非常简单:)

You need to specify the namespace:

// This is the default namespace within the feed, as specified
// xmlns="..." 
XNamespace ns = "http://www.w3.org/2005/Atom";

var feeds = from entry in feedXML.Descendants(ns + "entry")
            ...

Namespace handling is beautifully easy in LINQ to XML compared with everything other XML API I've ever used :)

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披肩女神 2024-11-16 02:55:54

您需要在 Descendents 和 Element 方法上指定命名空间。

XDocument feedXML = XDocument.Load(@"http://search.twitter.com/search.atom?q=twitter");

XNamespace ns = "http://www.w3.org/2005/Atom";
var feeds = from entry in feedXML.Descendants(ns + "entry")
            select new
            {
            PublicationDate = entry.Element(ns + "published").Value,
            Title = entry.Element(ns + "title").Value
            };

You need to specify a namespace on both the Descendents and Element methods.

XDocument feedXML = XDocument.Load(@"http://search.twitter.com/search.atom?q=twitter");

XNamespace ns = "http://www.w3.org/2005/Atom";
var feeds = from entry in feedXML.Descendants(ns + "entry")
            select new
            {
            PublicationDate = entry.Element(ns + "published").Value,
            Title = entry.Element(ns + "title").Value
            };

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豆芽 2024-11-16 02:55:54

如果你查看 HTTP 请求返回的 XML，你会发现它定义了一个 XML 命名空间：

<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" ...>
  <id>tag:search.twitter.com,2005:search/twitter</id>
  ...
</feed>

XML 就像 C# 一样，如果你使用了错误命名空间的元素名称，它不会被认为是同一个元素！您需要将所需的命名空间添加到查询中：

private static string AtomNamespace = "http://www.w3.org/2005/Atom";

public static XName Entry = XName.Get("entry", AtomNamespace);

public static XName Published = XName.Get("published", AtomNamespace);

public static XName Title = XName.Get("title", AtomNamespace);

var items = doc.Descendants(AtomConst.Entry)
                .Select(entryElement => new FeedItemViewModel()
                new {
                  Title = entryElement.Descendants(AtomConst.Title).Single().Value,
                  ...
                });

If you look at the XML returned by the HTTP request, you will see that it has an XML namespace defined:

<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" ...>
  <id>tag:search.twitter.com,2005:search/twitter</id>
  ...
</feed>

XML is just like C#, if you use an element name with the wrong namespace, it is not considered to be the same element! You need to add the required namepsace to your query:

private static string AtomNamespace = "http://www.w3.org/2005/Atom";

public static XName Entry = XName.Get("entry", AtomNamespace);

public static XName Published = XName.Get("published", AtomNamespace);

public static XName Title = XName.Get("title", AtomNamespace);

var items = doc.Descendants(AtomConst.Entry)
                .Select(entryElement => new FeedItemViewModel()
                new {
                  Title = entryElement.Descendants(AtomConst.Title).Single().Value,
                  ...
                });

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