XPath - node（）和text（）之间的区别 [英] XPath - Difference between node() and text()

问题描述

我无法理解 text（）和 node（）之间的区别。根据我的理解， text（）将是标签之间的任何东西< item> apple< / item> 这是苹果。节点将是实际上的节点，这将是项目

I'm having trouble understanding the difference between text() and node(). From what I understand, text() would be whatever is in between the tags <item>apple</item> which is apple in this case. Node would be whatever that node actually is, which would be item

但是，我已经分配了一些工作，要求我选择产品下的所有项目的文本，单独的问题询问选择所有部门的所有经理节点

But then I've been assigned some work where it asks me to "Select the text of all items under produce" and a separate question asks "Select all the manager nodes in all departments"

输出如何看起来 text（）而不是 node（）

How is the output suppose to look text() as opposed to node()

/ p>

snip of XML

<produce>
 <item>apple</item>
 <item>banana</item>
 <item>pepper</item>
</produce>

<department>
 <phone>123-456-7891</phone>
 <manager>John</manager>
</department>

当然，有更多的部门和更多的经理人，但这只是一段代码。

Of course, there are more departments and more managers, but this was just a snip of code.

任何帮助将不胜感激！

Any help would be much appreciated!

推荐答案

text（）和 ）是节点测试，在XPath术语（比较）中。

text() and node() are node tests, in XPath terminology (compare).

节点测试操作在一组（在 轴 ，并且返回一些类型的节点。当没有提到轴时，默认情况下假定 child 轴。

Node tests operate on a set (on an axis, to be exact) of nodes and return the ones that are of a certain type. When no axis is mentioned, the child axis is assumed by default.

有各种各样的节点测试：

• node（）匹配任何节点（它们的最小特定节点测试）


• text（）仅匹配文本节点


• comment（） 匹配评论节点


• * 匹配任何元素节点


• foo 匹配任何名为的元素节点foo / li>
  
• processing-instruction（）匹配PI节点（它们看起来像<？name value？> / code>）。


• 旁注： * 也匹配属性节点，但只能沿属性轴。 @ * 是 attribute :: * 的缩写。属性不是 child 轴的一部分，这就是为什么一般的 * 不会选择它们。

• node() matches any node (the least specific node test of them all)
• text() matches text nodes only
• comment() matches comment nodes
• * matches any element node
• foo matches any element node named "foo"
• processing-instruction() matches PI nodes (they look like <?name value?>).
• Side note: The * also matches attribute nodes, but only along the attribute axis. @* is a shorthand for attribute::*. Attributes are not part of the child axis, that's why a normal * does not select them.

此XML文档：

<produce>
    <item>apple</item>
    <item>banana</item>
    <item>pepper</item>
</produce>

代表以下DOM（简化）：

represents the following DOM (simplified):

root node
   element node (name="produce")
      text node (value="\n    ")
      element node (name="item")
         text node (value="apple")
      text node (value="\n    ")
      element node (name="item")
         text node (value="banana")
      text node (value="\n    ")
      element node (name="item")
         text node (value="pepper")
      text node (value="\n")

所以使用XPath：

• / 选择根节点


• / produce 选择根节点的子元素，如果它具有名称produce（这称为文档元素;它代表文档本身，文档元素和根节点常常被困惑，但它们不一样。）


• / produce / node（）选择 所有7个孩子）


• / produce / text（）选择4（！）空白的文本节点


• / produce / item [1] 选择名为的第一个子元素item li>
  
• / produce / item [1] / text（）选择所有子文本节点（只有一个 - 苹果 - 在这种情况下）

• / selects the root node
• /produce selects a child element of the root node if it has the name "produce" (This is called the document element; it represents the document itself. Document element and root node are often confused, but they are not the same thing.)
• /produce/node() selects any type of child node beneath /produce/ (i.e. all 7 children)
• /produce/text() selects the 4 (!) whitespace-only text nodes
• /produce/item[1] selects the first child element named "item"
• /produce/item[1]/text() selects all child text nodes (there's only one - "apple" - in this case)

等等。

所以，您的问题

• 选择产品下的所有项目的文本 /生成/ item / text（）（选择3个节点）


• 选择所有部门的所有经理节点 //部门/经理（选择1个节点）

• "Select the text of all items under produce" /produce/item/text() (3 nodes selected)
• "Select all the manager nodes in all departments" //department/manager (1 node selected)

Notes

• XPath中的默认轴是子轴。您可以通过以不同的轴名称前缀来更改轴。例如： // item / ancestor :: produce


• 元素节点具有文​​本值。评估元素节点时，将返回其文本内容。在这个例子中， / produce / item [1] / text（）和 string（/ produce / item [1]）将是一样的。


• 另请参阅这个答案，其中我以图形方式概述XPath表达式的各个部分。

• The default axis in XPath is the child axis. You can change the axis by prefixing a different axis name. For example: //item/ancestor::produce
• Element nodes have text values. When you evaluate an element node, its textual contents will be returned. In case of this example, /produce/item[1]/text() and string(/produce/item[1]) will be the same.
• Also see this answer where I outline the individual parts of an XPath expression graphically.

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