Adding subsription model and DB API

Model classes and a migration added for subscriptions handling. This
will be used later to build user feed.

Change-Id: I9012d3bc8b6c20d884100b23d431cdfd80457c1e

storyboard/db/api/subscriptions.py

@@ -0,0 +1,46 @@
+# Copyright (c) 2014 Mirantis Inc.
+#
+# 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.
+
+from storyboard.db.api import base as api_base
+from storyboard.db import models
+
+
+def subscription_get(subscription_id):
+    return api_base.entity_get(models.Subscription, subscription_id)
+
+
+def subscription_get_all(user_id):
+    return api_base.entity_get_all(models.Subscription, user_id=user_id)
+
+
+def subscription_get_all_by_target(target_type, target_id):
+    return api_base.entity_get_all(models.Subscription,
+                                   target_type=target_type,
+                                   target_id=target_id)
+
+
+def subscription_get_count(**kwargs):
+    return api_base.entity_get_count(models.Subscription, **kwargs)
+
+
+def subscription_create(values):
+    return api_base.entity_create(models.Subscription, values)
+
+
+def subscription_delete(subscription_id):
+    subscription = subscription_get(subscription_id)
+
+    if subscription:
+        api_base.entity_hard_delete(models.Subscription, subscription_id)

storyboard/db/migration/alembic_migrations/versions/021_subscription.py

@@ -0,0 +1,56 @@
+# 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.
+#
+
+"""This migration creates The subscription model primary and secondary tables.
+
+Revision ID: 021
+Revises: 020
+Create Date: 2014-07-10 15:37:30.662966
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '021'
+down_revision = '020'
+
+
+from alembic import op
+import sqlalchemy as sa
+
+MYSQL_ENGINE = 'InnoDB'
+MYSQL_CHARSET = 'utf8'
+
+target_type_enum = sa.Enum('task', 'story', 'project', 'project_group')
+
+
+def upgrade(active_plugins=None, options=None):
+
+    op.create_table(
+        'subscriptions',
+        sa.Column('created_at', sa.DateTime(), nullable=True),
+        sa.Column('updated_at', sa.DateTime(), nullable=True),
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('user_id', sa.Integer(), nullable=True),
+        sa.Column('target_type', target_type_enum, nullable=True),
+        sa.Column('target_id', sa.Integer(), nullable=True),
+        sa.PrimaryKeyConstraint('id'),
+        mysql_engine=MYSQL_ENGINE,
+        mysql_charset=MYSQL_CHARSET
+    )
+
+
+def downgrade(active_plugins=None, options=None):
+
+    op.drop_table('subscriptions')
+
+    target_type_enum.drop(op.get_bind())

storyboard/db/models.py

@@ -289,3 +289,15 @@ class Comment(Base):
 
     content = Column(UnicodeText)
     is_active = Column(Boolean, default=True)
+
+
+# Subscription and notifications
+
+class Subscription(Base):
+    _SUBSCRIPTION_TARGETS = ('task', 'story', 'project', 'project_group')
+
+    user_id = Column(Integer, ForeignKey('users.id'))
+    target_type = Column(Enum(*_SUBSCRIPTION_TARGETS))
+
+    # Cant use foreign key here as it depends on the type
+    target_id = Column(Integer)