XPATH 查询仅过滤某些属性的值 [英] XPATH query to filter values on certain attributes only

问题描述

我有以下 XML:

<Library>
 <Item>
  <Field Name="Name">smooth</Field>
  <Field Name="File Type">mid</Field>
  <Field Name="File Size">60026</Field>
 </Item>
 <Item>
  <Field Name="Name">mid</Field>
  <Field Name="File Type">mp3</Field>
  <Field Name="File Size">4584972</Field>
 </Item>
</Library>

我想获取文件类型为mid"的项目的所有项目名称.我的 XPATH 查询看起来像

I'd like to get all item names of items of the file type "mid". My XPATH query looks as

/Library/Item/Field
    [
    @Name="Name" and 
    (../Field[@Name="File Type" and ../Field[.="mid"]])
    ]

但不幸的是，这两个项目都从该查询中返回.

But unfortunately both items are returned from that query.

smooth
mid

似乎不是仅针对具有文件类型"属性的字段检查最后一个条件，而是针对所有字段检查.这会导致返回名称mid"，即使该项目的文件类型为mp3".

Seems that the last condition is not checked against fields with the attribute "File Type" only, but all fields. Which results in a return of the name "mid", even if this item is of file type "mp3".

如何将与mid"的比较限制为具有属性 Name="File Type" 的字段值?

How can I restrict the comparison with "mid" to the value of the field with the attribute Name="File Type"?

有人可以向我推荐一个按预期工作的 XPATH 语法吗?

Can anybody suggest me an XPATH syntax which works as expected?

推荐答案

XPath 谓词可以应用于任何地方，这会更直接:

XPath predicates can be applied anywhere, this would be more straight-forward:

/Library/Item[Field[@Name="File Type"] = "mid"]/Field[@Name="Name"]

你自己的表达是正确的

/Library/Item/Field[
  @Name="Name" 
  and ../Field[@Name="File Type"] = "mid"
]

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