Add polymorphic properties to User

This adds the ability to search for any user based on the generic
User case and be given back the specific LocalUser or RemoteUser.

This will require any code using the model to look which attributes
they are searching on and specify the specific User model they are
on if they're not on the generic User model. This will also require
new users to be created with LocalUser.

mediagoblin/db/migrations.py

@@ -1460,15 +1460,15 @@ def federation_user_create_tables(db):
     """
     Create all the tables
     """
+    metadata = MetaData(bind=db.bind)
+    user_table = inspect_table(metadata, "core__users")
+
     # Create tables needed
     LocalUser_V0.__table__.create(db.bind)
     RemoteUser_V0.__table__.create(db.bind)
     db.commit()
 
     # Create the fields
-    metadata = MetaData(bind=db.bind)
-    user_table = inspect_table(metadata, "core__users")
-
     updated_column = Column(
         "updated",
         DateTime,
@@ -1476,6 +1476,12 @@ def federation_user_create_tables(db):
     )
     updated_column.create(user_table)
 
+    type_column = Column(
+        "type",
+        Unicode
+    )
+    type_column.create(user_table)
+
     name_column = Column(
         "name",
         Unicode

mediagoblin/db/models.py

@@ -237,6 +237,9 @@ class User(Base, UserMixin):
     bio = Column(UnicodeText)
     name = Column(Unicode)
 
+    # This is required for the polymorphic inheritance
+    type = Column(Unicode)
+
     created = Column(DateTime, nullable=False, default=datetime.datetime.utcnow)
     updated = Column(DateTime, nullable=False, default=datetime.datetime.utcnow)
 
@@ -245,6 +248,11 @@ class User(Base, UserMixin):
     # Lazy getters
     get_location = relationship("Location", lazy="joined")
 
+    __mapper_args__ = {
+        'polymorphic_identity': 'user',
+        'polymorphic_on': type
+    }
+
     def has_privilege(self, privilege, allow_admin=True):
         """
         This method checks to make sure a user has all the correct privileges
@@ -324,6 +332,10 @@ class LocalUser(User):
     uploaded = Column(Integer, default=0)
     upload_limit = Column(Integer)
 
+    __mapper_args__ = {
+        'polymorphic_identity': 'user_local'
+    }
+
     ## TODO
     # plugin data would be in a separate model
 
@@ -394,6 +406,10 @@ class RemoteUser(User):
     id = Column(Integer, ForeignKey("core__users.id"), primary_key=True)
     webfinger = Column(Unicode, unique=True)
 
+    __mapper_args__ = {
+        'polymorphic_identity': 'user_remote'
+    }
+
     def __repr__(self):
         return "<{0} #{1} {2}>".format(
             self.__class__.__name__,