Validating with nested schema and namespaces

[Moritz Schepp]

Hey guys,

I'm trying to validate this document with nokogiri against its XSD at http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd:

<?xml version="1.0" encoding="UTF-8"?>
<OAI-PMH
  xmlns="http://www.openarchives.org/OAI/2.0/"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/
                      http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"
>
  <responseDate>2016-01-08T12:37:55Z</responseDate>
  <request verb="GetRecord">http://test.host/api/oai_pmh/kinds</request>
  <GetRecord>
  <record>
  <header>
    <identifier>12345</identifier>
    <datestamp>2016-01-08T12:37:55Z</datestamp>
  </header>
  <metadata>
    <oai_dc:dc
      xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/"
      xmlns:dc="http://purl.org/dc/elements/1.1/"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/
                          http://www.openarchives.org/OAI/2.0/oai_dc.xsd"
    >
      <dc:identifier>12345</dc:identifier>
      <dc:type>Type</dc:type>
      <dc:type>Kind</dc:type>
      <dc:type>EntityType</dc:type>


      <dc:description>some description</dc:description>
    </oai_dc:dc>
  </metadata>
</record>
</GetRecord>
</OAI-PMH>

My first question is: Can I tell nokogiri to figure out the XSD Schema itself or do I always have to provide it manually creating a Nokogiri::XML::Schema?

But more importantly, the validation doesn't work, I use the code 

xsd_response = HTTPClient.new.get "http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"
xsd = Nokogiri::XML::Schema(xsd_response.body)
doc = Nokogiri::XML(doc_string)
xsd.validate(doc).each do |error|
  puts "#{error.line} :: #{error.message}"
end

and I keep getting:

23 :: Element '{http://www.openarchives.org/OAI/2.0/oai_dc/}dc': No matching global element declaration available, but demanded by the strict wildcard.

Doesn't this mean that nokogiri doesn't find the xmlns:dc definitition on the oai_dc:dc element?

The validator at http://www.validome.org/xml/validate/ tells me that the doc is valid. Do you have an idea how I could validate it with nokogiri? This would be nice so I can integrate the validation into some unit tests.

[Mike Dalessio]

Hi Moritz,

Some context: Nokogiri has two different implementations, one is libxml2 (MRI/CRuby) and the other is Xerces (JRuby). This document and schema fail with the same error under both. Here's what JRuby's Nokogiri says:

 :: cvc-complex-type.2.4.c: The matching wildcard is strict, but no declaration can be found for element 'oai_dc:dc'.

Also worth noting is that if you ask validome to validate the schema at http://www.validome.org/grammar/ there are multiple errors as well.

Googling for the libxml2 error message gives this result:

https://mail.gnome.org/archives/xml/2009-November/msg00022.html

which is a question like yours about a schema that includes

<xs:any namespace="##other" />

which is the `metadataType` spec that appears to be giving the error. The reply to that post indicates that the cause may be that multiple schemas are necessary to fully validate the grammar.

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[Moritz Schepp]

Hey Mike,

thanks a lot for taking the time and for the thorough explanation! With the suggested workaround, our tests validate nicely.

I'm surprised though that this is a limitation of libxml, because it sounds a bit like a "wontfix".

BTW, I just passed

http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd and

http://www.openarchives.org/OAI/2.0/oai_dc.xsd

to 

http://www.validome.org/grammar/

and they both produced no errors. How exactly did you get any errors?

But in any case, we have a working solution. Thank you again.