以 xsd 中的值为条件 [英] Conditional on value in xsd

问题描述

有没有办法在标签值上添加条件?例如，我的 xml 看起来像这样:

is there any way to add conditions on a tag value? For example, my xml looks like this:

<Root>
 <Scheduler>
  <DateTimeType>DAY</DateTimeType>
  <DayOfWeek>Sunday</DayOfWeek> <!-- TAG IS ALLOWED -->
 </Scheduler>

 <Scheduler>
  <DateTimeType>MONTH</DateTimeType>
  <DayOfWeek>Sunday</DayOfWeek> <!-- TAG IS NOT ALLOWED -->
  <DayOfMonth>28</DayOfMonth> <!-- TAG IS ALLOWED -->
 </Scheduler>

 <Scheduler>
  <DateTimeType>WEEKDAY</DateTimeType>
  <DayOfWeek>Sunday</DayOfWeek> <!-- TAG IS ALLOWED -->
  <TimeOfDay>15:26</TimeOfDay> <!-- TAG IS ALLOWED -->
  <DayOfMonth>28</DayOfMonth> <!-- TAG IS NOT ALLOWED -->
 </Scheduler>

 <Scheduler>
  <DateTimeType>TIME</DateTimeType>
  <DayOfWeek>Sunday</DayOfWeek> <!-- TAG IS NOT ALLOWED -->
  <DayOfMonth>28</DayOfMonth> <!-- TAG IS NOT ALLOWED -->
  <TimeOfDay>15:26</TimeOfDay> <!-- TAG IS ALLOWED -->
 </Scheduler>
</Root>

我需要一个 XSD 方案，在我的 xml 中允许/不允许这些条件.

I need a XSD Scheme that allow/not allows these conditions in my xml.

谢谢.

推荐答案

如果 DateTimeType 是一个属性，则可以使用条件类型分配方便地完成此操作.但是如果它必须是一个子元素，你可以使用断言来实现，例如

If DateTimeType were an attribute, this could be done conveniently using conditional type assignment. But if it has to be a child element, you can do it using assertions, for example

<xs:assertion test="not(DateTimeType = 'MONTH' and exists(DayOfWeek)"/>

顺便说一下，它们不叫标签，它们叫元素.一个元素通常有两个标签，一个开始标签和一个结束标签.使用正确的术语有很多好处，例如，您会发现自己开始更好地理解错误消息中使用的语言.

By the way, they are not called tags, they are called elements. An element generally has two tags, a start tag and an end tag. Using the correct terminology has many benefits, for example you'll find that you start to understand the language used in error messages better.

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