xml XPath - node() 和 text() 之间的区别

XPath - Difference between node() and text()

提问by Pztar

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 applein this case. Node would be whatever that node actually is, which would be item

我无法理解之间的差异text()和node()。据我所知，在这种情况下text()，标签之间的任何东西<item>apple</item>都是苹果。节点将是该节点实际是什么，这将是项目

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"

但是后来我被分配了一些工作，它要求我“选择生产下所有项目的文本”，一个单独的问题询问“选择所有部门中的所有管理节点”

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

输出看起来如何text()，而不是node()

Snippet of XML:

XML 片段：

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

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

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

当然，还有更多的部门和更多的经理，但这只是一小段代码。

Any help would be much appreciated!

任何帮助将非常感激！

回答by Tomalak

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

text()并且node()是节点测试，在 XPath 术语中（比较）。

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 childaxis is assumed by default.

节点测试在一组（准确地说是在轴上）节点上运行，并返回特定类型的节点。当未提及child轴时，默认采用轴。

There are all kinds of node tests:

有各种节点测试：

• node()matches anynode (the least specific node test of them all)
• text()matches textnodes only
• comment()matches commentnodes
• *matches any elementnode
• foomatches 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 attributeaxis. @*is a shorthand for attribute::*. Attributes are not part of the childaxis, that's why a normal *does not select them.

• node()匹配任何节点（所有节点中最不具体的节点测试）
• 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"
• processing-instruction()匹配 PI 节点（它们看起来像<?name value?>）。
• 附注：本*也匹配属性节点，但仅沿attribute轴线。@*是 的简写attribute::*。属性不是child轴的一部分，这就是法线*不选择它们的原因。

This XML document:

此 XML 文档：

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

represents the following DOM (simplified):

代表以下 DOM（简化）：

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")

So with XPath:

所以使用 XPath：

• /selects the root node
• /produceselects 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 nodebeneath /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 allchild text nodes (there's only one - "apple" - in this case)

• /选择根节点
• /produce选择根节点的子元素，如果它有名字"produce"（这称为文档元素；它代表文档本身。文档元素和根节点经常混淆，但它们不是一回事。）
• /produce/node()选择任何类型的子节点的下方/produce/（即，所有7个孩子）
• /produce/text()选择 4 (!) 个纯空白文本节点
• /produce/item[1]选择第一个名为的子元素 "item"
• /produce/item[1]/text()选择所有子文本节点（只有一个 - “apple” - 在这种情况下）

And so on.

等等。

So, your questions

所以，你的问题

• "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)

• “选择生产下所有项目的文本”/produce/item/text()（选择了3个节点）
• “选择所有部门的所有管理节点”//department/manager（选择1个节点）

Notes

笔记

• The default axisin XPath is the childaxis. 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 answerwhere I outline the individual parts of an XPath expression graphically.

• XPath 中的默认轴是child轴。您可以通过为不同的轴名称添加前缀来更改轴。例如：//item/ancestor::produce
• 元素节点具有文​​本值。当您评估元素节点时，将返回其文本内容。在这个例子的情况下，/produce/item[1]/text()和string(/produce/item[1])将是相同的。
• 另请参阅此答案，其中我以图形方式概述了 XPath 表达式的各个部分。

回答by Danil Speransky

Select the text of all items under produce:

选择产品下所有项目的文本：

//produce/item/text()

Select all the manager nodes in all departments:

选择所有部门的所有管理节点：

//department/*