- docstring on polymorphic_mapping

- applied Simon Wittber's ActiveMapper version_id_col patch for [ticket:348]

lib/sqlalchemy/ext/activemapper.py

@@ -206,7 +206,9 @@ class ActiveMapperMeta(type):
         autoload   = False
         _metadata  = getattr(sys.modules[cls.__module__], 
                              "__metadata__", metadata)
-        
+        version_id_col = None
+        version_id_col_object = None
+
         if 'mapping' in dict:
             found_pk = False
             
@@ -223,7 +225,10 @@ class ActiveMapperMeta(type):
                 if '__autoload__' == name:
                     autoload = True
                     continue
-                    
+                
+                if '__version_id_col__' == name:
+                    version_id_col = value
+
                 if name.startswith('__'): continue
                 
                 if isinstance(value, column):
@@ -263,12 +268,16 @@ class ActiveMapperMeta(type):
                 cls.columns = cls.table._columns
             
             # check for inheritence
+            if version_id_col is not None:
+                version_id_col_object = getattr(cls.table.c, version_id_col, None)
+                assert(version_id_col_object is not None, "version_id_col (%s) does not exist." % version_id_col)
+
             if hasattr(bases[0], "mapping"):
                 cls._base_mapper= bases[0].mapper
                 assign_mapper(objectstore.context, cls, cls.table, 
-                              inherits=cls._base_mapper)
+                              inherits=cls._base_mapper, version_id_col=version_id_col_object)
             else:
-                assign_mapper(objectstore.context, cls, cls.table)
+                assign_mapper(objectstore.context, cls, cls.table, version_id_col=version_id_col_object)
             cls.relations = relations
             ActiveMapperMeta.classes[clsname] = cls
             

lib/sqlalchemy/orm/util.py

@@ -23,6 +23,9 @@ class CascadeOptions(object):
     
 
 def polymorphic_union(table_map, typecolname, aliasname='p_union'):
+    """create a UNION statement used by a polymorphic mapper.
+    
+    See the SQLAlchemy advanced mapping docs for an example of how this is used."""
     colnames = util.Set()
     colnamemaps = {}
     types = {}

test/ext/activemapper.py

@@ -1,6 +1,6 @@
 import testbase
 from sqlalchemy.ext.activemapper           import ActiveMapper, column, one_to_many, one_to_one, many_to_many, objectstore
-from sqlalchemy             import and_, or_, clear_mappers, backref
+from sqlalchemy             import and_, or_, clear_mappers, backref, create_session, exceptions
 from sqlalchemy             import ForeignKey, String, Integer, DateTime, Table, Column
 from datetime               import datetime
 import sqlalchemy
@@ -14,6 +14,7 @@ class testcase(testbase.PersistTest):
         
         class Person(ActiveMapper):
             class mapping:
+                __version_id_col__ = 'row_version'
                 full_name   = column(String)
                 first_name  = column(String)
                 middle_name = column(String)
@@ -24,6 +25,7 @@ class testcase(testbase.PersistTest):
                 home_phone  = column(String)
                 cell_phone  = column(String)
                 work_phone  = column(String)
+                row_version = column(Integer, default=0)
                 prefs_id    = column(Integer, foreign_key=ForeignKey('preferences.id'))
                 addresses   = one_to_many('Address', colname='person_id', backref='person', order_by=['state', 'city', 'postal_code'])
                 preferences = one_to_one('Preferences', colname='pref_id', backref='person')
@@ -137,7 +139,41 @@ class testcase(testbase.PersistTest):
         self.assertEquals(person.id, p1.id)
         self.assertEquals(len(person.addresses), 2)
         self.assertEquals(person.addresses[0].postal_code, '30338')
-    
+
+    @testbase.unsupported('mysql')
+    def test_update(self):
+        p1 = self.create_person_one()
+        objectstore.flush()
+        objectstore.clear()
+        
+        person = Person.select()[0]
+        person.gender = 'F'
+        objectstore.flush()
+        objectstore.clear()
+        self.assertEquals(person.row_version, 2)
+
+        person = Person.select()[0]
+        person.gender = 'M'
+        objectstore.flush()
+        objectstore.clear()
+        self.assertEquals(person.row_version, 3)
+
+        #TODO: check that a concurrent modification raises exception
+        p1 = Person.select()[0]
+        s1 = objectstore.session
+        s2 = create_session()
+        objectstore.context.current = s2
+        p2 = Person.select()[0]
+        p1.first_name = "jack"
+        p2.first_name = "ed"
+        objectstore.flush()
+        try:
+            objectstore.context.current = s1
+            objectstore.flush()
+            assert False
+        except exceptions.ConcurrentModificationError:
+            pass
+        
     
     def test_delete(self):
         p1 = self.create_person_one()