Conditional on value in xsd

Question

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>

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

Thanks.

Answer 1

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)"/>

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.