Detect Invalid sequence of tag in XML document using schema.

Stuart Dootson

Neither of your files should validate. I suspect your schema isn't parsing correctly, you're not checking errors and thinking that validation's happening. Your problems?

You can't use the ref attribute of the element element without using some level of XML namespaces.
You've omitted the Permission elements from your sample files
Your closing Permissions tags are incorrect - I'll presume that's a typo

Here's an xsd/xml pair that does cause the validation error you want (at least with libxml2): XSD file

<?xml version="1.0" encoding="utf-8"?>
<xs:schema
targetNamespace="http://test-namespace.com/"
xmlns="http://test-namespace.com/"
xmlns:srd="http://test-namespace.com/"
elementFormDefault="qualified" attributeFormDefault="unqualified"
xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:element name="Roles">
xs:complexType
xs:sequence
<xs:element ref ="Role"/>
</xs:sequence>
</xs:complexType>
</xs:element>

<xs:element name ="Role">
xs:complexType
xs:sequence
<xs:element ref="Permissions"/>
</xs:sequence>
</xs:complexType>
</xs:element>

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

</xs:schema>

XML file

<?xml version="1.0" encoding="utf-8"?>
<Roles xmlns="http://test-namespace.com/">
<Role>
<Permissions>
<Permission>Reader</Permission>
</Permissions>
</Role>
<Permissions>
<Permission>Reader</Permission>
</Permissions>
</Roles>

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

tprakash

Thank you very much. It worked perfectly :) .

tprakash

Hi, As you said we cannot use 'ref' attribute in xsd without using some level of xml namespace. Can we write a schema file (xsd) to valid the xml without having xmlns? Is there any other alternative to valid the xml without having xmlns? I mean, can we write xsd to valid the following xml? <?xml version="1.0" encoding="utf-8"?> <Roles> <Role> <Permissions> <Permission>Reader</Permission> </Permissions> </Role> <Permissions> <Permission>Reader</Permission> </Permissions> </Roles> Thanks. Prakash

Stuart Dootson

a) what's the hassle with using XML namespaces? Really isn't that much trouble. b) You can use something like this without namespaces. The references have effectively been manually resolved:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:element name="Roles">
xs:complexType
xs:sequence
<xs:element name ="Role">
xs:complexType
xs:sequence
<xs:element name ="Permissions">
xs:complexType
xs:sequence
<xs:element name ="Permission" type="xs:string" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>

</xs:schema>

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

tprakash

a) The XML file I am validating is from my clients. They cannot bear any change modification on that xml because it is being used by many others clients. They already working on the format of that xml. If I add an xml namespace in the XML file, all of my clients have to change their logic to read the modified XML file. What I can do is to write the xsd file to validate that XML file. It wouldn't have been problem if I could use namespace. I think your answer (b) will work for me. Thank your great help. Prakash

tprakash

I think the solution (b) works perfectly in cases where we have normal xml node. What about if the a child xml node contains parent xml node recursively? Taken the above case, what if Permissions node in turn contains the Roles ? Since we cannot use ref attribute, how to refer the Roles node in the above xsd? Thanks Prakash

Stuart Dootson

tprakash wrote:

The XML file I am validating is from my clients. They cannot bear any change modification on that xml because it is being used by many others clients

That I can understand. I presume your clients don't have a schema for their XML? In which case, what guarantees do you have that their XML will always match any schema you write? And how did they specify the XML format to you?

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Stuart Dootson

As I said in this message[^], I think I was wrong about not being able to use ref attributes. I'm not sure what was going on in my head that day :-) This schema validates your XML with libxml2 2.7.3 (which is a pretty recent release). I've put in the maxOccurs attribute of the sequence that contains the Permission element to enable multiple Permission elements in a Permissions element.

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:element name="Roles">
xs:complexType
xs:sequence
<xs:element ref ="Role"/>
</xs:sequence>
</xs:complexType>
</xs:element>

<xs:element name ="Role">
xs:complexType
xs:sequence
<xs:element ref="Permissions"/>
</xs:sequence>
</xs:complexType>
</xs:element>

<xs:element name ="Permissions">
xs:complexType
<xs:sequence maxOccurs="unbounded">
<xs:element name ="Permission" type="xs:string" />
</xs:sequence>
</xs:complexType>
</xs:element>

</xs:schema>

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

tprakash

Actually, we have two applications, one generates the xml, while other application consume the xml. The format of xml is defined by my management team. We have different clients using that applications(single only or both). And it is our management team decision not to change the format of the xml file. We just donot want to mesh up with that now. Otherwise, it is ok.

tprakash

Finally, I could create the desired xsd to valid the xml. I truly appreciate your great help. Thanks a lot. :) Prakash