I'm trying to validate an attribute value to only have 'true or false'. I tried using contains() and '|' or ',' to surround the possible values as below

contains(concat('|',//node()[local-name()='message']/@msgRequired,'|'),"|true|false|")

unfortunately it doesn't work so I had to do it the traditional way

//node()[local-name()='message']/@msgRequired="false" or //node()[local-name()='message']/@msgRequired="true"

But I have another validation need that is expecting 10 possible values and writing the traditional method as above maybe too much to do. So, I wonder if I clean the code above just a bit to make it easier to read or can I use contains() as described earlier?

Many thanks again!

contains() looks for a substring, whereas you seem to be trying to match the whole value, so you want "=".

The simplest approach is just to spell it out:

/path/node[.='true' or .='false' or .='maybe']

In XPath 2.0 you can write

/path/node[.=('true', 'false', 'maybe')]

or you can use regular expressions:

/path/node[matches(., '^(true|false|maybe)$')]

Another approach in XPath 1.0 is to put your strings in a lookup document

<values>
  <value>true</value>
  <value>false</value>
  <value>maybe</value>
</values>

and then

/path/node[. = $values/value]

assuming your API gives you a chance to bind the variable.


Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Hi Michael,

First of all, I bought your books (XSLT 2 and Professional XML). Bought them years back but never really got to appreciate XML until now that I am involved in a serious project.

Now I'm pulling my hair out because I have tons of pages to go through and time is against me.

I really appreciate your quick response to my inquiry. As for reference, I have this as a direct translation

//node()[local-name()='message']/@msgRequired [.='true' or .='false' or .='maybe']

Everything is fine now. :)

Thanks and more power!