Enables polymorphic subclasses on users

HISTORY.rst

@@ -4,6 +4,9 @@ Changelog
 - Adds user groups.
   [msom]
 
+- Enables polymorphic subclasses on users.
+  [msom]
+
 0.14.1 (2017-07-12)
 ~~~~~~~~~~~~~~~~~~~
 

onegov/user/models/user.py

@@ -18,6 +18,16 @@ class User(Base, TimestampMixin, ORMSearchable):
 
     __tablename__ = 'users'
 
+    #: the type of the item, this can be used to create custom polymorphic
+    #: subclasses of this class. See
+    #: `<http://docs.sqlalchemy.org/en/improve_toc/\
+    #: orm/extensions/declarative/inheritance.html>`_.
+    type = Column(Text, nullable=True)
+
+    __mapper_args__ = {
+        'polymorphic_on': type
+    }
+
     es_language = 'de'  # XXX add to database in the future
     es_properties = {
         'username': {'type': 'text'},

onegov/user/tests/test_models.py

@@ -41,3 +41,39 @@ def test_user_group(session):
     assert group.users.one() == user
     assert user.group == group
     assert user.group_id == group.id
+
+
+def test_polymorphism_user(session):
+
+    class MyUser(User):
+        __mapper_args__ = {'polymorphic_identity': 'my'}
+
+    class MyOtherUser(User):
+        __mapper_args__ = {'polymorphic_identity': 'other'}
+
+    session.add(User(username='default', password='pwd', role='editor'))
+    session.add(MyUser(username='my', password='pwd', role='editor'))
+    session.add(MyOtherUser(username='other', password='pwd', role='editor'))
+    session.flush()
+
+    assert session.query(User).count() == 3
+    assert session.query(MyUser).one().username == 'my'
+    assert session.query(MyOtherUser).one().username == 'other'
+
+
+def test_polymorphism_group(session):
+
+    class MyGroup(UserGroup):
+        __mapper_args__ = {'polymorphic_identity': 'my'}
+
+    class MyOtherGroup(UserGroup):
+        __mapper_args__ = {'polymorphic_identity': 'other'}
+
+    session.add(UserGroup(name='original'))
+    session.add(MyGroup(name='my'))
+    session.add(MyOtherGroup(name='other'))
+    session.flush()
+
+    assert session.query(UserGroup).count() == 3
+    assert session.query(MyGroup).one().name == 'my'
+    assert session.query(MyOtherGroup).one().name == 'other'

onegov/user/upgrade.py

@@ -190,4 +190,11 @@ def add_group_id_column(context):
             Column('group_id', UUID, nullable=True)
         )
 
-# add user.type
+
+@upgrade_task('Add type column')
+def add_type_column(context):
+    if not context.has_column('users', 'type'):
+        context.operations.add_column(
+            'users',
+            Column('type', Text, nullable=True)
+        )