Some improvements on relation registry stuff

git-svn-id: svn://svn.cy55.de/Zope3/src/cybertools/trunk@1089 fd906abe-77d9-0310-91a1-e0d9ade77398

relation/README.txt

@@ -87,11 +87,15 @@ reference these objects via IntIds later; the __parent__ and __name__
 attributes are also needed later when we send an IObjectRemovedEvent event):
 
   >>> from persistent import Persistent
+  >>> from zope.interface import implements
+  >>> from cybertools.relation.interfaces import IRelatable
+
   >>> class Person(Persistent):
   ...     __name__ = __parent__ = None
+  ...     implements(IRelatable)
 
   >>> class City(Persistent):
-  ...     pass
+  ...     implements(IRelatable)
 
   >>> clark = Person()
   >>> kirk = Person()
@@ -138,6 +142,12 @@ relations, first and second:
   >>> len(nyRels)
   2
 
+We can also query the registry using an example relation:
+
+  >>> clarkRels = relations.query(example=LivesIn(clark, None))
+  >>> len(clarkRels)
+  1
+
 It is also possible to remove a relation from the relation registry:
 
   >>> relations.unregister(
@@ -254,6 +264,12 @@ if we want to access relations by array index:
   >>> len(nyRels)
   2
 
+We can also query the registry using an example relation:
+
+  >>> clarkRels = relations.query(example=LivesIn(clark, None))
+  >>> len(clarkRels)
+  1
+
   >>> relations.unregister(
   ...     list(relations.query(first=audrey, second=newyork))[0]
   ... )
@@ -355,10 +371,12 @@ creating a special relation class that uses named predicates.
   >>> class PredicateRelation(DyadicRelation):
   ...     def __init__(self, predicate, first, second):
   ...         self.predicate = predicate
+  ...         predicate.forClass = self.__class__
   ...         self.first = first
   ...         self.second = second
   ...     def getPredicateName(self):
-  ...         return self.predicate.getPredicateName()
+  ...         baseName = super(PredicateRelation, self).getPredicateName()
+  ...         return '.'.join((baseName, self.predicate.name))
 
 We also need a class for the predicate objects that will be used for
 the constructor of the NamedPredicateRelation class:
@@ -370,7 +388,10 @@ the constructor of the NamedPredicateRelation class:
   ...     implements(IPredicate)
   ...     def __init__(self, name):
   ...         self.name = name
+  ...         self.forClass = None
   ...     def getPredicateName(self):
+  ...         if self.forClass is not None:
+  ...             return self.forClass(self, None, None).getPredicateName()
   ...         return self.name
 
 We can now create a predicate with the name '_lives in_' (that may replace

relation/__init__.py

@@ -29,6 +29,7 @@ from persistent import Persistent
 from zope.interface import implements
 from interfaces import IPredicate
 from interfaces import IRelation, IDyadicRelation, ITriadicRelation
+from interfaces import IRelatable
 
 class Relation(Persistent):
 
@@ -41,6 +42,12 @@ class Relation(Persistent):
     def validate(self, registry=None):
         return True
 
+    def checkRelatable(self, *objects):
+        for obj in objects:
+            if obj is not None and not IRelatable.providedBy(obj):
+                raise(ValueError, 'Objects to be used in relations '
+                        'must provide the IRelatable interface.')
+    
 
 class DyadicRelation(Relation):
     
@@ -49,6 +56,7 @@ class DyadicRelation(Relation):
     def __init__(self, first, second):
         self.first = first
         self.second = second
+        self.checkRelatable(first, second)
 
 
 class TriadicRelation(Relation):
@@ -59,4 +67,5 @@ class TriadicRelation(Relation):
         self.first = first
         self.second = second
         self.third = third
+        self.checkRelatable(first, second, third)
 

relation/interfaces.py

@@ -71,6 +71,23 @@ class ITriadicRelation(IDyadicRelation):
     third = Attribute('Third object that belongs to the relation.')
 
 
+# this is just a conceptual try - thinking about storing
+# relations as attributes...
+class IAttributeRelation(IDyadicRelation):
+    """ A type of relation that will be stored in attributes of the
+        objects that take part in the relation. You have to use a
+        relation registry that provides IAttributeRelationRegistry
+        for registering/managing relations of this type.
+    """
+
+    attributeNameFirst = Attribute('Name of the attribute in which the '
+                        'relation will be stored on the `first` object. '
+                        'Typically a class attribute.')
+    attributeNameSecond = Attribute('Name of the attribute in which the '
+                        'relation will be stored on the `second` object.'
+                        'Typically a class attribute.')
+
+
 class IPredicate(Interface):
     """ A predicate signifies a relationship. This may be implemented
         directly as a relation class, or the relation object may 
@@ -90,6 +107,15 @@ class IRelationInvalidatedEvent(IObjectEvent):
     """
 
 
+# marker interfaces
+
+class IRelatable(Interface):
+    """ Marker interface for objects that may have relations associated
+        with them. Should be checked by IRelationRegistry.register()
+        and event handlers.
+    """
+
+
 # relation registry interfaces
     
 class IRelationRegistryUpdate(Interface):
@@ -105,15 +131,12 @@ class IRelationRegistryUpdate(Interface):
         """ Remove the relation given from this registry.
         """
 
-#BBB
-#IRelationsRegistryUpdate = IRelationRegistryUpdate
-
 
 class IRelationRegistryQuery(Interface):
     """ Interface for querying a relation registry.
     """
 
-    def query(relation=None, **kw):
+    def query(example=None, **kw):
         """ Return a sequence of relations that fulfill the criteria given.
 
             You may provide a relation object as an example that specifies the
@@ -125,8 +148,6 @@ class IRelationRegistryQuery(Interface):
                 rr.queryRelations(first=someObject, second=anotherObject,
                                   relationship=SomeRelationClass)
         """
-#BBB
-#IRelationsRegistryQuery = IRelationRegistryQuery
 
 
 class IRelationRegistry(IRelationRegistryUpdate, IRelationRegistryQuery):
@@ -134,6 +155,4 @@ class IRelationRegistry(IRelationRegistryUpdate, IRelationRegistryQuery):
         implemented as a local utility .
     """
 
-#BBB
-#IRelationsRegistry = IRelationRegistry
 

relation/registry.py

@@ -57,23 +57,27 @@ class DummyRelationRegistry(object):
     
     def query(self, example=None, **kw):
         result = []
+        criteria = {}
+        if example is not None:
+            for attr in ('first', 'second', 'third',):
+                value = getattr(example, attr, None)
+                if value is not None:
+                    criteria[attr] = value
+            criteria['relationship'] = example
+        criteria.update(kw)
         for r in self.relations:
             hit = True
-            for k in kw:
+            for k in criteria:
-                #if ((k == 'relationship' and r.__class__ != kw[k])
                 if ((k == 'relationship'
-                        and r.getPredicateName() != kw[k].getPredicateName())
+                        and r.getPredicateName() != criteria[k].getPredicateName())
                  or (k != 'relationship'
-                        and (not hasattr(r, k) or getattr(r, k) != kw[k]))):
+                        and (not hasattr(r, k) or getattr(r, k) != criteria[k]))):
                     hit = False
                     break
             if hit:
                 result.append(r)
         return result
 
-#BBB
-#DummyRelationsRegistry = DummyRelationRegistry
-
 
 class RelationRegistry(Catalog):
     """ Local utility for registering (cataloguing) and searching relations.
@@ -97,14 +101,26 @@ class RelationRegistry(Catalog):
         notify(RelationInvalidatedEvent(relation))
 
     def query(self, example=None, **kw):
+        intIds = zapi.getUtility(IIntIds)
+        criteria = {}
+        if example is not None:
+            for attr in ('first', 'second', 'third',):
+                value = getattr(example, attr, None)
+                if value is not None:
+                    criteria[attr] = intIds.getId(value)
+            pn = example.getPredicateName()
+            if pn:
+                criteria['relationship'] = pn
         for k in kw:
+            # overwrite example fields with explicit values
             if k == 'relationship':
-                quString = kw[k].getPredicateName()
+                criteria[k] = kw[k].getPredicateName()
             else:
-                quString = zapi.getUtility(IIntIds).getId(kw[k])
+                criteria[k] = intIds.getId(kw[k])
+        for k in criteria:
             # set min, max
-            kw[k] = (quString, quString)
+            criteria[k] = (criteria[k], criteria[k])
-        return self.searchResults(**kw)
+        return self.searchResults(**criteria)
 
 #BBB
 #RelationsRegistry = RelationRegistry
@@ -207,9 +223,13 @@ def invalidateRelations(context, event):
     """ Handles IObjectRemoved event: unregisters
         all relations the object to be removed is involved in.
     """
+    # TODO: check marker interface of object:
+    # if not IRelatable.providedBy(event.object):
+    #     return
     relations = []
-    registry = zapi.queryUtility(IRelationRegistry)
+    #registry = zapi.queryUtility(IRelationRegistry)
-    if registry is not None:
+    registries = zapi.getAllUtilitiesRegisteredFor(IRelationRegistry)
+    for registry in registries:
         for attr in ('first', 'second', 'third'):
             relations = registry.query(**{attr: context})
             for relation in relations: