Add ability to merge 2 user accounts

tailbone/views/master.py

@@ -482,7 +482,11 @@ class MasterView(View):
         return result
 
     def merge_objects(self, removing, keeping):
-        raise NotImplementedError("please implement `{}.merge_objects()`".format(self.__class__.__name__))
+        """
+        Merge the two given objects.  You should probably override this;
+        default behavior is merely to delete the 'removing' object.
+        """
+        self.Session.delete(removing)
 
     ##############################
     # Core Stuff

tailbone/views/users.py

@@ -129,6 +129,19 @@ class UsersView(PrincipalMasterView):
     Master view for the User model.
     """
     model_class = model.User
+    mergeable = True
+    merge_additive_fields = [
+        'sent_message_count',
+        'received_message_count',
+    ]
+    merge_fields = merge_additive_fields + [
+        'uuid',
+        'username',
+        'person_uuid',
+        'person_name',
+        'role_count',
+        'active',
+    ]
 
     def query(self, session):
         return session.query(model.User)\
@@ -202,6 +215,31 @@ class UsersView(PrincipalMasterView):
                 users.append(user)
         return users
 
+    def get_merge_data(self, user):
+        return {
+            'uuid': user.uuid,
+            'username': user.username,
+            'person_uuid': user.person_uuid,
+            'person_name': user.person.display_name if user.person else None,
+            '_roles': user.roles,
+            'role_count': len(user.roles),
+            'active': user.active,
+            'sent_message_count': len(user.sent_messages),
+            'received_message_count': len(user._messages),
+        }
+
+    def get_merge_resulting_data(self, remove, keep):
+        result = super(UsersView, self).get_merge_resulting_data(remove, keep)
+        result['role_count'] = len(set(remove['_roles'] + keep['_roles']))
+        return result
+
+    def merge_objects(self, removing, keeping):
+        # TODO: merge roles, messages
+        assert not removing.sent_messages
+        assert not removing._messages
+        assert not removing._roles
+        self.Session.delete(removing)
+
 
 class UserVersionView(VersionView):
     """