How to ignore the validation of Unknown tags?

Question

One more challenge to the XSD capability,

I have been sending XML files by my clients, which will be having 0 or more undefined or [call] unexpected tags (May appear in hierarchy). Well they are redundant tags for me .. so I have got to ignore their presence, but along with them there are some set of tags which are required to be validated.

This is a sample XML:

<root>
  <undefined_1>one</undefined_1>
  <undefined_2>two</undefined_2>
  <node>to_be_validated</node>
  <undefined_3>two</undefined_3>
  <undefined_4>two</undefined_4>
</root>

And the XSD I tried with:

  <xs:element name="root" type="root"></xs:element>
  <xs:complexType name="root">
    <xs:sequence>
      <xs:any maxOccurs="2" minOccurs="0"/>
      <xs:element name="node" type="xs:string"/>
      <xs:any maxOccurs="2" minOccurs="0"/>
    </xs:sequence>
  </xs:complexType

XSD doesn't allow this, due to certain reasons.
The above mentioned example is just a sample. The practical XML comes with the complex hierarchy of XML tags ..

Kindly let me know if you can get a hack of it.

By the way, The alternative solution is to insert XSL-transformation, before validation process. Well, I am avoiding it because I need to change the .Net code which triggers validation process, which is supported at the least by my company.

Eire

Is the problem that it does not validate against the schema? – Morbidity

yup .. rather I wanted to show that "I don't know how do it .. and I tried THIS" .. – Eire

Answer 1

Conclusion:

This is not possible with XSD. All the approaches I was trying to achieve the requirement were named as "ambiguous" by validation-tools, accompanying bunch of errors.

Eire

Answer 2

In case your not already done with this, you might try the following:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="root" type="root"></xs:element>
  <xs:complexType name="root">
    <xs:sequence>
      <xs:any maxOccurs="2" minOccurs="0" processContents="skip"/>
      <xs:element name="node" type="xs:string"/>
      <xs:any maxOccurs="2" minOccurs="0" processContents="skip"/>
    </xs:sequence>
  </xs:complexType>
</xs:schema>

Under Linux this works fine with xmllint using libxml version 20706.

Karrikarrie

however it still doesn't allow first element to be ANY! :( – Eire

What exactly is the issue, please? – Karrikarrie

this is the error I am getting : Wildcard '##any' allows element 'node', and causes the content model to become ambiguous. so and so – Eire

This looks like a conceptunal problem. For details please see here: w3.org/TR/xmlschema-1/#cos-nonambig An interesting fact to me is that obviously differnt tools handle this case differently. As I wrote, the solution provide by my does work with the tools mentioned. – Karrikarrie

Well. Thanks for the info and ur valuable time :) it was helpful though I cannot implement it coz I have got to deal only with .net :) – Eire

Answer 3

You could make use of a new feature in XML 1.1 called "Open Content". In short, it allows you to specify that additional "unknown" elements can be added to a complex type in various positions, and what the parser should do if it hit any of those elements.

Using XML 1.1, your complex type would become:

<xs:element name="root" type="root" />
<xs:complexType name="root"> 
  <xs:openContent mode="interleave">
    <xs:any namespace="##any" processContents="skip"/>
  </xs:openContent>

  <xs:sequence> 
    <xs:element name="node" type="xs:string"/> 
  </xs:sequence> 
</xs:complexType>

If you have a lot of complex types, you can also set a "default" open content mode at the top of your schema:

<xs:schema ...>
  <xs:defaultOpenContent mode="interleave">
    <xs:any namespace="##any" processContents="skip"/>
  </xs:defaultOpenContent>

  ...
</xs:schema>

The W3C spec for Open Content can be found at http://www.w3.org/TR/xmlschema11-1/#oc, and there's a good writeup of this at http://www.ibm.com/developerworks/library/x-xml11pt3/#N102BA.

Unfortunately, .NET doesn't support XML 1.1 as of yet I can't find any free XML 1.1 processors - but a couple of paid-for options are:

• http://www.saxonica.com/
• http://www.altova.com/raptorxml.html

Kandi

Could someone explain why I can't get this to work here: utilities-online.info/xsdvalidation. Does this simply not support XSD 1.1? I get: Element '{w3.org/2001/XMLSchema}schema': The content is not valid. Expected is ((include | import | redefine | annotation)*, (((simpleType | complexType | group | attributeGroup) | element | attribute | notation), annotation*)*). when using the exact example proposed here. – Clupeoid

Answer 4

Maybe its is possible to use namespaces:

<xs:element name="root" type="root"></xs:element> 
  <xs:complexType name="root"> 
    <xs:sequence> 
      <xs:any maxOccurs="2" minOccurs="0" namespace="http://ns1.com" /> 
      <xs:element name="node" type="xs:string"/> 
      <xs:any maxOccurs="2" minOccurs="0" namespace="http://ns2.com"/> 
    </xs:sequence> 
  </xs:complexType>

This will probably validate.

Unruly

well thought [+1].. but unfortunately doesn't work in my case. thanx for the response. :-) – Eire

Answer 5

I faced the same problem.

Since I called the validation from .NET; I decided to suppress the specific validation error in ValidationEventHandler as a workaround. It worked for me.

    private void ValidationEventHandler(object sender, ValidationEventArgs e)
    {
        switch (e.Severity)
        {
            case XmlSeverityType.Warning:
                // Processing warnings
                break;
            case XmlSeverityType.Error:
                if (IgnoreUnknownTags
                    && e.Exception is XmlSchemaValidationException
                    && new Regex(
                        @"The element '.*' has invalid child element '.*'\."
                        + @" List of possible elements expected:'.*'\.")
                       .IsMatch(e.Exception.Message))
                {
                    return;
                }
                // Processing errors
                break;
            default:
                throw new InvalidEnumArgumentException("Severity should be one of the valid values");
        }
    }

It is important that Thread.CurrentUICulture must be set to English or CultureInfo.InvariantCulture for the current thread for this to work.

Rigney