Added a new rates table.

We only need one rate per channel. This reflects that. The provider_rates has been left for now, it is still not being used.
New dao has been added to select the right rate for the given notification_type and date of notificaiton.

app/dao/rates_dao.py

@@ -0,0 +1,11 @@
+from sqlalchemy import desc
+
+from app import db
+from app.models import Rates
+
+
+def get_rate_for_type_and_date(notification_type, date_sent):
+    return db.session.query(Rates).filter(Rates.notification_type == notification_type,
+                                          Rates.valid_from <= date_sent
+                                          ).order_by(Rates.valid_from.desc()
+                                                     ).limit(1).first()

app/models.py

@@ -944,3 +944,12 @@ class Event(db.Model):
         nullable=False,
         default=datetime.datetime.utcnow)
     data = db.Column(JSON, nullable=False)
+
+
+class Rates(db.Model):
+    __tablename__ = 'rates'
+
+    id = db.Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    valid_from = db.Column(db.DateTime, nullable=False)
+    rate = db.Column(db.Numeric(), nullable=False)
+    notification_type = db.Column(notification_types, index=True, nullable=False)

migrations/versions/0074_update_sms_rate.py

@@ -0,0 +1,28 @@
+"""empty message
+
+Revision ID: 0074_update_sms_rate
+Revises: 0072_add_dvla_orgs
+Create Date: 2017-04-24 12:10:02.116278
+
+"""
+
+import uuid
+
+revision = '0074_update_sms_rate'
+down_revision = '0072_add_dvla_orgs'
+
+from alembic import op
+
+
+def upgrade():
+    op.get_bind()
+    op.execute("INSERT INTO provider_rates (id, valid_from, rate, provider_id) "
+               "VALUES ('{}', '2017-04-01 00:00:00', 1.58, "
+               "(SELECT id FROM provider_details WHERE identifier = 'mmg'))".format(uuid.uuid4())
+               )
+
+
+def downgrade():
+    op.get_bind()
+    op.execute("DELETE FROM provider_rates where valid_from = '2017-04-01 00:00:00' "
+               "and provider_id = (SELECT id FROM provider_details WHERE identifier = 'mmg')")

migrations/versions/0075_create_rates_table.py

@@ -0,0 +1,40 @@
+"""empty message
+
+Revision ID: 0075_create_rates_table
+Revises: 0074_update_sms_rate
+Create Date: 2017-04-24 15:12:18.907629
+
+"""
+
+# revision identifiers, used by Alembic.
+import uuid
+
+revision = '0075_create_rates_table'
+down_revision = '0074_update_sms_rate'
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+def upgrade():
+    notification_types = postgresql.ENUM('email', 'sms', 'letter', name='notification_type', create_type=False)
+    op.create_table('rates',
+    sa.Column('id', postgresql.UUID(as_uuid=True), nullable=False),
+    sa.Column('valid_from', sa.DateTime(), nullable=False),
+    sa.Column('rate', sa.Numeric(), nullable=False),
+    sa.Column('notification_type', notification_types, nullable=False),
+    sa.PrimaryKeyConstraint('id')
+    )
+
+    op.create_index(op.f('ix_rates_notification_type'), 'rates', ['notification_type'], unique=False)
+
+    op.get_bind()
+    op.execute("INSERT INTO rates(id, valid_from, rate, notification_type) "
+               "VALUES('{}', '2016-05-18 00:00:00', 1.65, 'sms')".format(uuid.uuid4()))
+    op.execute("INSERT INTO rates(id, valid_from, rate, notification_type) "
+               "VALUES('{}', '2017-04-01 00:00:00', 1.58, 'sms')".format(uuid.uuid4()))
+
+
+def downgrade():
+    op.drop_index(op.f('ix_rates_notification_type'), table_name='rates')
+    op.drop_table('rates')

tests/app/dao/test_rates_dao.py

@@ -0,0 +1,18 @@
+from datetime import datetime
+
+from decimal import Decimal
+
+from app.dao.rates_dao import get_rate_for_type_and_date
+
+
+def test_get_rate_for_type_and_date(notify_db):
+    rate = get_rate_for_type_and_date('sms', datetime.utcnow())
+    assert rate.rate == Decimal("1.58")
+
+    rate = get_rate_for_type_and_date('sms', datetime(2016, 6, 1))
+    assert rate.rate == Decimal("1.65")
+
+
+def test_get_rate_for_type_and_date_early_date(notify_db):
+    rate = get_rate_for_type_and_date('sms', datetime(2014, 6, 1))
+    assert not rate