如何在XPATH中获取特定标签？

Question

我正在尝试获取p标签,但尚未成功.以下是我想要获得的数据.

  for $i in $data
    let $ptag := $i//*[p]/text()

  (: $data example :)
  <div xmlns="http://www.w3.org/1999/xhtml">
    <div class="title">my title</div>
    <div class="course">
      <div class="room">112</div>
      <div class="teacher">Mr. Wilson</div>
      <div class="student">123456</div>
      <p>approved</p>
    </div>
  </div>

Answer 1

两个问题:

1. 该p元素绑定到XHTML名称空间.您正在"无名称空间"中引用名为"p"的元素.声明XHTML命名空间并在XPath中使用namespace-prefix.
2. 谓词(方括号)的行为类似于SQL where子句,并且是方括号前面的项目的filteres.您的原始XPath试图解决具有子元素的text()任何元素中的所有节点,而不是从所有XHTML p元素中选择所有节点.$dataptext()

(: declare a namespace prefix for the XHTML namespace, 
   in order to use in the XPath below :)
declare namespace x="http://www.w3.org/1999/xhtml";

(: $data example :)
let $data :=
  <div xmlns="http://www.w3.org/1999/xhtml">
    <div class="title">my title</div>
    <div class="course">
      <div class="room">112</div>
      <div class="teacher">Mr. Wilson</div>
      <div class="student">123456</div>
      <p>approved</p>
    </div>
  </div>

return
  for $i in $data
  (: use the namespace prefix "x" when addressing the HTML p element 
     and pull it out of the predicate
   :)
  let $ptag := $i//x:p/text()
  return $ptag