- unit-of-work does a better check for "orphaned" objects that are

part of a "delete-orphan" cascade, for certain conditions where the
parent isnt available to cascade from.
- it is now invalid to declare a self-referential relationship with
"delete-orphan" (as the abovementioned check would make them impossible
to save)
- improved the check for objects being part of a session when the
unit of work seeks to flush() them as part of a relationship..

4 files changed, 27 insertions, 4 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index ab0226a41..2347da2ba 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -86,6 +86,7 @@ class Mapper(object):
         self.properties = properties or {}
         self.allow_column_override = allow_column_override
         self.allow_null_pks = allow_null_pks
+        self.delete_orphans = []
         
         # a Column which is used during a select operation to retrieve the 
         # "polymorphic identity" of the row, which indicates which Mapper should be used
@@ -139,6 +140,13 @@ class Mapper(object):
         # of dependency
         #self.compile()
     
+    def _is_orphan(self, obj):
+        for (key,klass) in self.delete_orphans:
+            if not getattr(klass, key).hasparent(obj):
+                return True
+        else:
+            return False
+            
     def _get_props(self):
         self.compile()
         return self.__props
diff --git a/lib/sqlalchemy/orm/properties.py b/lib/sqlalchemy/orm/properties.py
index b5d66c160..16760dc06 100644
--- a/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@ -216,6 +216,11 @@ class PropertyLoader(mapper.MapperProperty):
         
         self.target = self.mapper.mapped_table
 
+        if self.cascade.delete_orphan:
+            if self.parent.class_ is self.mapper.class_:
+                raise exceptions.ArgumentError("Cant establish 'delete-orphan' cascade rule on a self-referential relationship.  You probably want cascade='all', which includes delete cascading but not orphan detection.")
+            self.mapper.primary_mapper().delete_orphans.append((self.key, self.parent.class_))
+            
         if self.secondaryjoin is not None and self.secondary is None:
             raise exceptions.ArgumentError("Property '" + self.key + "' specified with secondary join condition but no secondary argument")
         # if join conditions were not specified, figure them out based on foreign keys
diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index 5c962aa39..e5c95cbe4 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -350,6 +350,12 @@ class Session(object):
                 raise exceptions.InvalidRequestError("Instance '%s' is a detached instance or is already persistent in a different Session" % repr(object))
         else:
             m = class_mapper(object.__class__, entity_name=kwargs.get('entity_name', None))
+            
+            # this would be a nice exception to raise...however this is incompatible with a contextual 
+            # session which puts all objects into the session upon construction.
+            #if m._is_orphan(object):
+            #    raise exceptions.InvalidRequestError("Instance '%s' is an orphan, and must be attached to a parent object to be saved" % (repr(object)))
+            
             m._assign_entity_name(object)
             self._register_new(object)
 
diff --git a/lib/sqlalchemy/orm/unitofwork.py b/lib/sqlalchemy/orm/unitofwork.py
index 33e0149e4..00d34a104 100644
--- a/lib/sqlalchemy/orm/unitofwork.py
+++ b/lib/sqlalchemy/orm/unitofwork.py
@@ -106,9 +106,10 @@ class UnitOfWork(object):
             pass
 
     def _validate_obj(self, obj):
-        if hasattr(obj, '_instance_key') and not self.identity_map.has_key(obj._instance_key):
-            raise InvalidRequestError("Instance '%s' is not attached or pending within this session" % repr(obj._instance_key))
-        
+        if (hasattr(obj, '_instance_key') and not self.identity_map.has_key(obj._instance_key)) or \
+            (not hasattr(obj, '_instance_key') and obj not in self.new):
+            raise InvalidRequestError("Instance '%s' is not attached or pending within this session" % repr(obj))
+
     def update(self, obj):
         """called to add an object to this UnitOfWork as though it were loaded from the DB,
         but is actually coming from somewhere else, like a web session or similar."""
@@ -184,7 +185,10 @@ class UnitOfWork(object):
                 continue
             if obj in self.deleted:
                 continue
-            flush_context.register_object(obj)
+            if object_mapper(obj)._is_orphan(obj):
+                flush_context.register_object(obj, isdelete=True)
+            else:
+                flush_context.register_object(obj)
             
         for obj in self.deleted:
             if objset is not None and not obj in objset: