1 files changed, 71 insertions, 0 deletions
diff --git a/schema/validate.py b/schema/validate.py
new file mode 100644
index 00000000..56eb7230
--- /dev/null
+++ b/schema/validate.py
@@ -0,0 +1,71 @@
+import rdflib
+
+
+class ValidationError(Exception):
+    pass
+
+class UnknownClass(ValidationError):
+    def __init__(self, owl_class):
+        super(UnknownClass, self).__init__(
+            "Class %s is not defined by the given schema." % owl_class)
+
+
+def check_data_against_schema(data, schema):
+    '''Validate data against a schema.
+
+    The data is assumed to be an RDFLib.Graph instance containing a set of
+    arbitrary triples.
+
+    The schema is assumed to be an RDFLib.Graph instance containing one or more
+    OWL ontologies.
+
+    This function assumes 'data' should be completely authorative according to
+    the schema (i.e. everything that must be known about a resource is known).
+    You can see this as assuming a "closed world" rather than an "open world".
+    It also assumes there should be nothing in 'data' that the schema does not
+    describe.
+
+    '''
+    for uriref in data.subjects():
+        resource = rdflib.resource.Resource(data, uriref)
+        validate_resource(resource, data, schema)
+
+
+def validate_resource(resource, data, schema):
+    RDF = rdflib.RDF
+    OWL = rdflib.OWL
+
+    # Are the type of 'resource' all classes defined in the schema?
+    classes = schema[:RDF.type:OWL.Class]
+    resource_types = resource.value(RDF.type)
+
+    for resource_type in resource_types:
+        if resource_type.identifier not in classes:
+            raise UnknownClass(resource_type)
+
+    resource_property_value_pairs = resource.predicate_objects()
+    for prop, value in resource_property_value_pairs:
+        validate_resource_property(resource, prop, value, data,
+                                   schema)
+
+
+def validate_resource_property(resource, prop, value, data, schema):
+    RDF = rdflib.RDF
+    OWL = rdflib.OWL
+
+    resource_types = resource.value(RDF.type)
+
+    prop_uriref = prop.identifier
+
+    # FIXME: this gives no results at all ...
+    prop = rdflib.resource.Resource(schema, prop)
+    print list(prop.items())
+
+    # But this gives the expected results. :(
+    print list(schema[prop_uriref:])
+
+    # FIXME: some properties are defined in rdfs, dc, owl, .... need those
+    # ontologies available to validate too.
+
+    import pdb
+    pdb.set_trace()