Validation String XSLT WSO2 - xslt

Question

I'm newbie about validation on programming. Like Checking string and checking field input empty or not. Maybe anyone in here can share me about simple sample validation rule about string and checking field to me with XSLT. Thanks

Answer 1

First of all, XSLT is for XML transformations and if you want to do schema validations you should be looking at XSD validations. Having said that below is how you can use XSLT to validate a message and generate a payload.
Let's say you have a Payload like the below.
<Request>
<messages>
<message>
<id>123</id>
<name>Not Empty</name>
</message>
<message>
<id>234</id>
<name></name>
</message>
</messages>
</Request>
In the above payload, you want to check each message and check whether the name is empty or not. Inorder to validate this you can use XSLT. First create a XSLT as a LocalEntry in the local-entries directory. You can use the following content. (You can create your XSLT in the registry as well)
<?xml version="1.0" encoding="UTF-8"?>
<localEntry key="LOCAL_XSLT_NullCheck" xmlns="http://ws.apache.org/ns/synapse">
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output encoding="UTF-8" indent="yes" method="xml" omit-xml-declaration="yes"/>
<xsl:template match="/">
<Response>
<!-- Iterating through message elements -->
<xsl:for-each select="//messages/message">
<message>
<messageID><xsl:value-of select="id/text()"/></messageID>
<xsl:choose>
<!-- Check if name is empty -->
<xsl:when test="boolean(name/text())">
<isEmpty>false</isEmpty>
</xsl:when>
<xsl:otherwise>
<isEmpty>true</isEmpty>
</xsl:otherwise>
</xsl:choose>
</message>
</xsl:for-each>
</Response>
</xsl:template>
</xsl:stylesheet>
</localEntry>
Next create a API to consume your request and to validate the payload and then to generate the response.
<?xml version="1.0" encoding="UTF-8"?>
<api context="/xslt" name="TestAPI" xmlns="http://ws.apache.org/ns/synapse">
<resource methods="POST">
<inSequence>
<log level="full">
<property name="Message" value="Incoming Message"/>
</log>
<xslt key="LOCAL_XSLT_NullCheck"/>
<respond/>
</inSequence>
<outSequence/>
<faultSequence/>
</resource>
</api>
Now once you invoke the API with the aforementioned message. You should see the following response.
<Response xmlns="http://ws.apache.org/ns/synapse">
<message>
<messageID>123</messageID>
<isEmpty>false</isEmpty>
</message>
<message>
<messageID>234</messageID>
<isEmpty>true</isEmpty>
</message>
</Response>
You ca read more on XSLT mediator from here. You can also consider using FastXSLT Mediator as well based on your requirement. Read more on XSLT from here.