Linq到XML查询不起作用 [英] Linq to XML query not working

问题描述

  Dim  BookingDatabase  As  XDocument = XDocument.Load（  https://itunes.apple.com/us/rss/topsongs/limit=10/xml） 
 
  Dim  feeds =来自feed   BookingDatabase.Descendants（ 条目）
 选择 mytitle = feed .Element（  title）。价值，
 myrights = feed.Element（  rights）。值
 
 
 对于 每个提要在提要
  Dim  myLabel  As  新标签
 myLabel.Text = feed.mytitle.First.ToString&    - & feed.myrights.First.ToString 
 PlaceHolder1.Controls.Add（myLabel）
 
  Next  

我看不出我做错了什么 - 但没有结果

想法？

解决方案

XML您加载的文档的默认命名空间为 http://www.w3.org/2005/Atom - 您需要在元素名称中包含该命名空间：

  Dim  atom  As  XNamespace =   http://www.w3.org/2005/Atom 
  Dim  BookingDatabase 作为 XDocument = XDocument.Load（  https://itunes.apple.com/us/rss/topsongs/limit=10/xml）
 
  Dim  feeds =来自Feed   BookingDatabase.Descendants（atom +   entry）
 选择 mytitle = feed.Element（atom +   title）。值， 
 myrights = feed.Element（atom +   rights）。值

Dim BookingDatabase As XDocument = XDocument.Load("https://itunes.apple.com/us/rss/topsongs/limit=10/xml")

Dim feeds = From feed In BookingDatabase.Descendants("entry")
       Select mytitle = feed.Element("title").Value,
           myrights = feed.Element("rights").Value

      
For Each feed In feeds
   Dim myLabel As New Label
   myLabel.Text = feed.mytitle.First.ToString & " - " & feed.myrights.First.ToString            
    PlaceHolder1.Controls.Add(myLabel)

Next

I can't see what I have done wrong - but no results
Ideas?

解决方案

The XML document you've loaded has a default namespace of http://www.w3.org/2005/Atom - you need to include that namespace in the element names:

Dim atom As XNamespace = "http://www.w3.org/2005/Atom"
Dim BookingDatabase As XDocument = XDocument.Load("https://itunes.apple.com/us/rss/topsongs/limit=10/xml")

Dim feeds = From feed In BookingDatabase.Descendants(atom + "entry")
    Select mytitle = feed.Element(atom + "title").Value,
    myrights = feed.Element(atom + "rights").Value

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