def _load_subtype_fact(self, xml_node):
""" Load a subtype fact, which indicates a subtype constraint. Note,
we chose not to move this node under <Constraints>, because it must
be loaded prior to any associated XOR/IOR constraints. """
attribs, name = get_basic_attribs(xml_node)
# Get super and sub type XML nodes
factroles = find(xml_node, "FactRoles")
super_node = find(factroles, "SupertypeMetaRole")
sub_node = find(factroles, "SubtypeMetaRole")
supertype_node = find(super_node, "RolePlayer")
subtype_node = find(sub_node, "RolePlayer")
# Look-up the corresponding object types
try:
supertype = self._elements[supertype_node.get("ref")]
subtype = self._elements[subtype_node.get("ref")]
except KeyError:
raise Exception("Cannot load subtype constraint.")
# Does this subtype constraint provide a path to the preferred ID?
path = (xml_node.get("PreferredIdentificationPath") == "true")
# Create constraint
cons = Constraint.SubtypeConstraint(subtype, supertype, path,
**attribs)
# If there are additional constraints on the subtype (e.g. XOR or IOR),
# their role sequence will consist of the subtype fact's roles. We will
# redirect the id for those roles to this constraint, so that the covers
# attribute is a list of SubtypeConstraints for constraints on subtypes.
self._elements[super_node.get("id")] = cons
self._elements[sub_node.get("id")] = cons
self._add(cons)
def test_commit_and_rollback_subtype(self):
""" Test commit and rollback of a subtype constraint. """
obj1 = ObjectType(name="O1")
obj2 = ObjectType(name="O2")
cons = Constraint.SubtypeConstraint(subtype=obj1, supertype=obj2)
self.assertEquals(obj1.covered_by, [])
self.assertEquals(obj1.direct_subtypes, [])
self.assertEquals(obj1.direct_supertypes, [])
self.assertEquals(obj2.covered_by, [])
self.assertEquals(obj2.direct_subtypes, [])
self.assertEquals(obj2.direct_supertypes, [])
cons.commit()
self.assertEquals(obj1.covered_by, [cons])
self.assertEquals(obj1.direct_subtypes, [])
self.assertEquals(obj1.direct_supertypes, [obj2])
self.assertEquals(obj2.covered_by, [cons])
self.assertEquals(obj2.direct_subtypes, [obj1])
self.assertEquals(obj2.direct_supertypes, [])
with self.assertRaises(NotImplementedError):
cons.rollback()
# The commented out code below was used before I decided to raise
# NotImplementedError for rollback. See the comments in rollback().
"""