CNN 媒体：content media="image" SyndicationFeed答案

【问题标题】：CNN media:content medium="image" SyndicationFeedCNN 媒体：content media="image" SyndicationFeed
【发布时间】：2018-05-13 13:03:55
【问题描述】：

我正在尝试从 CNN 的 RSS 提要中获取图像值，但在获取它时遇到了问题。

我追求的是来自

的价值

 <media:content medium="image" 
                url="https://cdn.cnn.com/cnnnext/dam/assets/180513143656-police-masks-surabaya-hp-video.jpg" 
                height="144" 
                width="256" />

通过下面的代码，我可以看到我在追求什么，但我无法检索到值。

foreach (SyndicationElementExtension extension in f.ElementExtensions)
{
    XElement element = extension.GetObject<XElement>();
    if (element.HasAttributes)
    {
        foreach (var attribute in element.Attributes())
        {
             //How to get value here    
        }
    }
}

如何检索图像值？

【问题讨论】：

标签： c# xml linq-to-xml syndication-feed

【解决方案1】：

您可以通过使用 Linq 来实现。

  var urlElem = element.Attributes().FirstOrDefault(a => a.Name == "url");
  if(urlElem!=null)
  {
     Console.Write(urlElem.Value);
  }

别忘了使用：

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

【讨论】：

更简单：element.Attribute("url");

【解决方案2】：

尽量接近你所拥有的，这将在 CNN RSS 提要中列出来自 medium="image" 的所有 url：

var ns = (XNamespace) "http://search.yahoo.com/mrss/";  // namespace of the extension

SyndicationFeed feed = SyndicationFeed.Load(XmlReader.Create(@"http://rss.cnn.com/rss/edition.rss"));

var urls = from item in feed.Items              // all items
           from ext in  item.ElementExtensions  // all extensions to ext
           where ext.OuterName == "group" &&    // find the ones called group
                 ext.OuterNamespace == ns       // in the right namespace
           from content in ext.GetObject<XElement>().Elements(ns + "content") // get content elements
           where (string) content.Attribute("medium") == "image"  // if that medium is an image
           select (string) content.Attribute("url");              // get the url

// output what is in urls
foreach(string url in urls) 
{
      Console.WriteLine(url);
}

最重要的是GetObject<XElement>() 确实为您提供了group 元素，但该元素本身没有medium 和url 属性。您必须枚举名为 content 的子元素，并且每个元素都具有您感兴趣的属性。

如果您还需要宽度和高度，您可以轻松地将它们投影到最终选择中：

select new { 
            url = (string) content.Attribute("url"),
            h = (int) content.Attribute("height"),
            w = (int) content.Attribute("width") 
           };

【讨论】：

【解决方案3】：

这些项目没有任何值。这是 xml 的示例：

    <item>
      <title><![CDATA[Trump says he's working with China to save tech firm crushed by US ban]]></title>
      <link>http://money.cnn.com/2018/05/13/technology/business/trump-zte-corporation-china-commerce/index.html</link>
      <guid isPermaLink="true">http://money.cnn.com/2018/05/13/technology/business/trump-zte-corporation-china-commerce/index.html</guid>
      <pubDate>Sun, 13 May 2018 22:38:18 GMT</pubDate>
      <media:group>
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-super-169.jpg" height="619" width="1100" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-large-11.jpg" height="300" width="300" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-vertical-large-gallery.jpg" height="552" width="414" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-video-synd-2.jpg" height="480" width="640" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-live-video.jpg" height="324" width="576" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-t1-main.jpg" height="250" width="250" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-vertical-gallery.jpg" height="360" width="270" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-story-body.jpg" height="169" width="300" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-t1-main.jpg" height="250" width="250" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-assign.jpg" height="186" width="248" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510091942-zte-office-shanghai-hp-video.jpg" height="144" width="256" />
      </media:group>
    </item>
    <item>
      <title><![CDATA[US officials offer North Korea 'prosperity' for de-nuking]]></title>
      <link>https://www.cnn.com/collections/north-korea-intl-051318/</link>
      <guid isPermaLink="true">https://www.cnn.com/collections/north-korea-intl-051318/</guid>
      <pubDate>Sun, 13 May 2018 18:36:04 GMT</pubDate>
      <media:group>
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-super-169.jpg" height="619" width="1100" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-large-11.jpg" height="300" width="300" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-vertical-large-gallery.jpg" height="552" width="414" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-video-synd-2.jpg" height="480" width="640" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-live-video.jpg" height="324" width="576" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-t1-main.jpg" height="250" width="250" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-vertical-gallery.jpg" height="360" width="270" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-story-body.jpg" height="169" width="300" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-t1-main.jpg" height="250" width="250" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-assign.jpg" height="186" width="248" />
        <media:content medium="image" url="https://cdn.cnn.com/cnnnext/dam/assets/180510111120-20180510-trump-kim-illo-01-hp-video.jpg" height="144" width="256" />
      </media:group>
    </item>

【讨论】：