Article Title and Tag Updates

As Schematron is so closely related to XSLT and other related languages such as XQuery, in the new year, we have decided to begin providing XSLT tips in addition to the Schematron tips.  We will be updating the prior posts tags and titles to help differentiate the Schematron from the XSLT articles.  We apologize for any inconvenience or confusion these updates may cause.

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.