Add an "in_reply_to" column to comments

This will be used to allow comments to be a reply to another
comment, to allow for threaded discussions.

Change-Id: I87d9a59f9dae204029a8c390c4d35628f21fd390

storyboard/api/v1/wmodels.py

@@ -42,6 +42,9 @@ class Comment(base.APIBase):
     is_active = bool
     """Is this an active comment, or has it been deleted?"""
 
+    in_reply_to = int
+    """The ID of the parent comment, if any."""
+
 
 class SystemInfo(base.APIBase):
     """Represents the system information for Storyboard

storyboard/db/migration/alembic_migrations/versions/055_allow_comments_to_be_replies_to_other_.py

@@ -0,0 +1,40 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+
+"""Allow comments to be replies to other comments
+
+Revision ID: 055
+Revises: 054
+Create Date: 2016-03-05 23:35:40.379333
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '055'
+down_revision = '054'
+
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade(active_plugins=None, options=None):
+    op.add_column(
+        'comments', sa.Column('in_reply_to', sa.Integer(), nullable=True))
+    op.create_foreign_key(
+        'comments_ibfk_1', 'comments', 'comments', ['in_reply_to'], ['id'])
+
+
+def downgrade(active_plugins=None, options=None):
+    op.drop_constraint('comments_ibfk_1', 'comments', type_='foreignkey')
+    op.drop_column('comments', 'in_reply_to')

storyboard/db/models.py

@@ -490,8 +490,11 @@ class TimeLineEvent(ModelBuilder, Base):
 class Comment(FullText, ModelBuilder, Base):
     __fulltext_columns__ = ['content']
 
+    id = Column(Integer, primary_key=True)
     content = Column(MYSQL_MEDIUM_TEXT)
     is_active = Column(Boolean, default=True)
+    in_reply_to = Column(Integer, ForeignKey('comments.id'))
+    parent = relationship('Comment', remote_side=[id], backref='children')
 
 
 # Subscription and notifications