Validating an XML document fragment against XML schema
- by shylent
Terribly sorry if I've failed to find a duplicate of this question.
I have a certain document with a well-defined document structure. I am expressing that structure through an XML schema.
That data structure is operated upon by a RESTful service, so various nodes and combinations of nodes (not the whole document, but fragments of it) are exposed as "resources". Naturally, I am doing my own validation of the actual data, but it makes sense to validate the incoming/outgoing data against the schema as well (before the fine-grained validation of the data).
What I don't quite grasp is how to validate document fragments given the schema definition.
Let me illustrate:
Imagine, the example document structure is:
<doc-root>
<el name="foo"/>
<el name="bar"/>
</doc-root>
Rather a trivial data structure. The schema goes something like this:
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:element name="doc-root">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="el" type="myCustomType" />
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:complexType name="myCustomType">
<xsd:attribute name="name" use="required" />
</xsd:complexType>
</xsd:schema>
Now, imagine, I've just received a PUT request to update an 'el' object. Naturally, I would receive not the full document or not any xml, starting with 'doc-root' at its root, but the 'el' element itself. I would very much like to validate it against the existing schema then, but just running it through a validating parser wouldn't work, since it will expect a 'doc-root' at the root.
So, again, the question is, - how can one validate a document fragment against an existing schema, or, perhaps, how can a schema be written to allow such an approach.
Hope it made sense.
