Change how we populate and retrieve MonthlyBilling totals:

1. For both email and sms, store [] in monthly_totals if
there is no billing data (no notifications sent etc.) and
return this via the API

2. General refactoring of indentation

app/dao/monthly_billing_dao.py

@@ -1,5 +1,8 @@
 from datetime import datetime
 
+from sqlalchemy import func
+
+
 from app import db
 from app.dao.dao_utils import transactional
 from app.dao.date_util import get_month_start_and_end_date_in_utc, get_financial_year
@@ -31,16 +34,19 @@ def create_or_update_monthly_billing(service_id, billing_month):
     _update_monthly_billing(service_id, start_date, end_date, EMAIL_TYPE)
 
 
-def _monthly_billing_data_to_json(monthly):
-    # total cost must take into account the free allowance.
-    # might be a good idea to capture free allowance in this table
-    return [{
-        "billing_units": x.billing_units,
-        "rate_multiplier": x.rate_multiplier,
-        "international": x.international,
-        "rate": x.rate,
-        "total_cost": (x.billing_units * x.rate_multiplier) * x.rate
-    } for x in monthly]
+def _monthly_billing_data_to_json(billing_data):
+    results = []
+    if billing_data:
+        # total cost must take into account the free allowance.
+        # might be a good idea to capture free allowance in this table
+        results = [{
+            "billing_units": x.billing_units,
+            "rate_multiplier": x.rate_multiplier,
+            "international": x.international,
+            "rate": x.rate,
+            "total_cost": (x.billing_units * x.rate_multiplier) * x.rate
+        } for x in billing_data]
+    return results
 
 
 @transactional
@@ -82,7 +88,11 @@ def get_monthly_billing_entry(service_id, start_date, notification_type):
 def get_yearly_billing_data_for_date_range(
     service_id, start_date, end_date, notification_types
 ):
-    results = MonthlyBilling.query.filter(
+    results = db.session.query(
+        MonthlyBilling.notification_type,
+        MonthlyBilling.monthly_totals,
+        MonthlyBilling.start_date,
+    ).filter(
         MonthlyBilling.service_id == service_id,
         MonthlyBilling.start_date >= start_date,
         MonthlyBilling.end_date <= end_date,
@@ -112,5 +122,4 @@ def get_billing_data_for_financial_year(service_id, year, notification_types=[SM
     results = get_yearly_billing_data_for_date_range(
         service_id, start_date, end_date, notification_types
     )
-
     return results

app/dao/notification_usage_dao.py

@@ -127,6 +127,7 @@ def email_yearly_billing_data_query(service_id, start_date, end_date, rate=0):
         rate_multiplier(),
         NotificationHistory.international
     ).first()
+
     if not result:
         return [(0, 0, 1, EMAIL_TYPE, False, 0)]
     else:
@@ -187,9 +188,14 @@ def is_between(date, start_date, end_date):
 
 def billing_data_per_month_query(rate, service_id, start_date, end_date, notification_type):
     month = get_london_month_from_utc_column(NotificationHistory.created_at)
-    result = db.session.query(
+    if notification_type == SMS_TYPE:
+        filter_subq = func.sum(NotificationHistory.billable_units).label('billing_units')
+    elif notification_type == EMAIL_TYPE:
+        filter_subq = func.count(NotificationHistory.billable_units).label('billing_units')
+
+    results = db.session.query(
         month.label('month'),
-        func.sum(NotificationHistory.billable_units).label('billing_units'),
+        filter_subq,
         rate_multiplier().label('rate_multiplier'),
         NotificationHistory.international,
         NotificationHistory.notification_type,
@@ -206,17 +212,7 @@ def billing_data_per_month_query(rate, service_id, start_date, end_date, notific
         rate_multiplier()
     ).all()
 
-    if not result and notification_type == EMAIL_TYPE:
-        start_date = convert_utc_to_bst(start_date)
-        BillingData = namedtuple(
-            'BillingData',
-            'start_date billing_units rate_multiplier international notification_type rate'
-        )
-        return [BillingData(start_date, 0, 1, False, notification_type, 0)]
-    else:
-        return result
-
-    return result
+    return results
 
 
 def rate_multiplier():