Greetings. While working on an XML based project for work, I ran into the following bug with the libxml2 validator. I've attached a simple test case that, when run through xmllint, should reproduce the same results I am receiving.
The problem is as follows. The supplied libxml2 validator, xmllint, will fail to validate the following instance document against the schema specified below if you uncomment the line specified in the instance document; however when it is commented, the instance document will validate just fine. Instance document: ------------------ <?xml version="1.0" encoding="UTF-8"?> <TestRoot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; xsi:noNamespaceSchemaLocation="common-schema.xsd"> <Events> <TestEvent>Test 1.</TestEvent> <!-- Uncomment the following element to cause libxml's xmllint to fail to validate. --> <!-- <TestEvent>Test 2.</TestEvent> --> </Events> </TestRoot> Schema to validate against: --------------------------- <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"; elementFormDefault="qualified" attributeFormDefault="unqualified"> <!-- This is the head of our substitution group for events that have only simple content. --> <xs:element name="SimpleEvent" type="SimpleEventType"/> <!-- All SimpleEvent elements have the required set of attributes --> <xs:complexType name="SimpleEventType"> <xs:simpleContent> <xs:extension base="xs:anySimpleType"> </xs:extension> </xs:simpleContent> </xs:complexType> <!-- Common members of the SimpleEvent substitution group --> <xs:element name="TestEvent" substitutionGroup="SimpleEvent"> <xs:complexType> <xs:simpleContent> <xs:restriction base="SimpleEventType"> <xs:simpleType> <xs:restriction base="xs:string"/> </xs:simpleType> </xs:restriction> </xs:simpleContent> </xs:complexType> </xs:element> <!-- Root element --> <xs:element name="TestRoot" type="TestRootType"/> <!-- Core data type of an audit trail --> <xs:complexType name="TestRootType"> <xs:sequence> <xs:element name="Events"> <xs:complexType> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element ref="SimpleEvent"/> </xs:choice> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:schema> I have done numerous test cases and pinned the problem to be the fact that a substitution group is being used inside the choice group element, which is specified to appear zero or more times in an instance document. The key is that each choice group contains one SimpleEvent, or any element that can be substitutable for SimpleEvent (in this case, TestEvent is declared to be part of the SimpleEvent substitution group, so it should work just fine). In essense, any choice group that contains an element that can be substituted by another element in the corresponding substitution group, and if the schema allows for that choice group to appear multiple times in an instance document, then the validator will fail to validate any instance document that has more than substitutable element specified (as in the above case when the second SimpleElement is uncommented from the instance document). >From what I can gather, the libxml2 validator is getting confused and instead >of thinking that the two TestEvent elements in the original instance document belong to two separate choice groups, it actually thinks that they are both in the same choice group. If this is true, this would explain the error message that is obtained when I run xmllint: "element TestEvent: Schemas validity error : Element 'TestEvent': This element is not expected." I have tried changing the choice group to a sequence group, and the exact same error occurs. I have also used the following validators, and they all will validate the supplied instance document against the supplied schema without any problem: Xerces, MSXML 4.0 SP2, MSXML.NET, and XSV, hence leading me to believe this is truly a bug with the libxml2 validator. I've also filled out a Bugzilla bug report describing what has been described in this post. Thanks, Michael Romer _______________________________________________ xml mailing list, project page http://xmlsoft.org/ [email protected] http://mail.gnome.org/mailman/listinfo/xml
