Question

我在读取一些xml-lines时遇到了XPathSelectElement的问题....

函数handleEachSession从我的其他函数中的mathod childList.ForEach（）调用两次：

private void handleMonitorResponse(XElement receivedSessions)
 {
 List<XElement> childList = receivedSessions.Elements().ToList();
 childList.ForEach(handleEachSession);

childList有两个元素（两行XML，我想要的那些）然后我可以在调试器中看到handleEachSession（）的两次调用都获得了正确的XElement会话。那两个我希望它有。

现在有这些XPathSelectElement。它适用于第一次通话但不适用于第二次通话。第二次我得到新的XElement会话，但XPathSelectElement仍然返回第一次调用的旧值。哼！？？我无法理解这种行为。

private void handleEachSession(XElement session)
 {
 XElement receivedSessionId = session.XPathSelectElement("//sessionId");
 XElement receivedQuality = session.XPathSelectElement("//quality");
 XElement receivedContentStatus = session.XPathSelectElement("//contentStatus");
…

有人可以帮助我吗？

XML是：

receivedSessions = 
<sessions type="array">
  <item type="object">
    <sessionId type="string">8c86716a87</sessionId>
    <quality type="string">mid</quality>
    <addressUri type="string">http://192.168.6.234/media/SorrowPinkFloyd_.mp4</addressUri>
    <currentTime type="number">1.5542887</currentTime>
    <contentStatus type="string">paused</contentStatus>
  </item>
  <item type="object">
    <sessionId type="string">c795067c4e</sessionId>
    <quality type="string">mid</quality>
    <addressUri type="string">http://192.168.6.234/media/trailer.mp4</addressUri>
    <currentTime type="number">3.3492105</currentTime>
    <contentStatus type="string">playing</contentStatus>
  </item>
</sessions>

session = (first call)
<item type="object">
  <sessionId type="string">8c86716a87</sessionId>
  <quality type="string">mid</quality>
  <addressUri type="string">http://192.168.6.234/media/SorrowPinkFloyd_.mp4</addressUri>
  <currentTime type="number">1.5542887</currentTime>
  <contentStatus type="string">paused</contentStatus>
</item>

session = (second call)
<item type="object">
  <sessionId type="string">c795067c4e</sessionId>
  <quality type="string">mid</quality>
  <addressUri type="string">http://192.168.6.234/media/trailer.mp4</addressUri>
  <currentTime type="number">3.3492105</currentTime>
  <contentStatus type="string">playing</contentStatus>
</item>

Answer 1

根据xpath-syntax，双斜杠（//）表示：从当前节点中选择与选择匹配的文档中的节点，无论它们在何处。因此，考虑到这一点，您可能需要将handleEachSession功能更改为

private void handleEachSession(XElement session)
{
    XElement receivedSessionId = session.XPathSelectElement("sessionId");
    XElement receivedQuality = session.XPathSelectElement("quality");
    XElement receivedContentStatus = session.XPathSelectElement("contentStatus");
}

C＃ - Linq - XPathSelectElement每次返回相同的结果

1 个答案: