XSD Validation in MarkLogic

04 January 2011

Sometimes you want to ensure that your xml document matches a given schema (xsd). Xquery on MarkLogic gives you a few tools to do this. If you want to validate your xml against an xsd, read on fair reader.

First of all, you need an xsd schema to show the database what you expect your data to look like. From the w3schools xsd example , here's a sweet schema:

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
	targetNamespace="http://www.w3schools.com"
	xmlns="http://www.w3schools.com"
	elementFormDefault="qualified">

	<xs:element name="note">
	  <xs:complexType>
		<xs:sequence>
		  <xs:element name="to" type="xs:string"/>
		  <xs:element name="from" type="xs:string"/>
		  <xs:element name="heading" type="xs:string"/>
		  <xs:element name="body" type="xs:string"/>
		</xs:sequence>
	  </xs:complexType>
	</xs:element>

	</xs:schema>

First, save the xsd in the Schemas database. If you want to webdav in, connect to port 8902 and create a directory structure that matches the xsd target namespace:

http://  >  www.w3schools.com

And drop your schema in there.

If you want to verify the location of your xsds, run a little cmd in CQ against the Schemas db:

fn:base-uri(/xs:schema)

Next, let's get us a document to validate (again, from w3schools' example):

<note>
  <to>April</to>
  <from>Jake</from>
  <heading>Reminder</heading>
  <body>Don't forget me this weekend!</body>
</note>

And finally to validate. There are two modes, strict (default) and lax. I've been using strict, because lax really is. And a little more CQ action:

	import module namespace functx = "http://www.functx.com" at "/MarkLogic/functx/functx-1.0-nodoc-2007-01.xqy";
	let $document := 
		
		  April
		  Jake
		  Reminder
		  Don't forget me this weekend!
		
	let $doc-to-validate := functx:change-element-ns-deep( $document, "http://www.w3schools.com", "awesome" )
	return validate strict { $doc-to-validate }

To explain, we pull in our doc, we attach a namespace to it (since we didn't already specify one), and validate away. If your doc fails validation against the schema, prepare to see the first error encountered. In another experiment, I was getting beauties like these:

  • validate strict { $doc-to-validate } -- Missing element declaration: Expected declaration for node ...
  • validate strict { $doc-to-validate } -- Missing required attribute: Found () but required (@type & @uuid? ...
  • validate strict { $doc-to-validate } -- Invalid node type: @type lexical value "asdf" invalid for expected type ...

Beauties, eh?

The one-at-a-time error reported stinketh a bit to me. With a function whose job it is to provide a picture of how well (or not) a document matches a schema, I think it would be more fitting to provide a report (perhaps in beautiful xml) of what all the issues are that were found.

Cheers! And a happy new year filled with valid documents.