Schematron: Trim Whitespace When Testing String Length

As discussed in previous posts, the string-length() > 0 test is useful in checking to be sure null values are not passed; a validation step that raw XSD does not natively perform.  This ensures the following is NOT allowed:

<nc:PersonGivenName></nc:PersonGivenName>

It also prevents the following:

<nc:PersonGivenName/>

However, if white space is not trimmed, the following WOULD be allowed:

<nc:PersonGivenName>  </nc:PersonGivenName>

In order to trim leading and trailing white space, the built-in XSLT function normalize-space() can be used.  This in effect eliminates the above scenario where spaces have been inserted into the string.  This can be seen in the following example:

<assert test="string-length(normalize-space(nc:PersonGivenName)) &gt; 0"/>
  Person's first name may not be left blank.
</assert>

Be aware, that this function also eliminates redundant spaces between characters (including duplicate carriage returns and line-feeds) so a custom replace() function may be required if you wish to preserve those extra characters in your string length checks.