Update the last template usage query to check Notification table:

* Don't check the NotificationHistory table (this can cause a timeout)
* Check template actually exists first

app/dao/notifications_dao.py

@@ -149,11 +149,11 @@ def dao_get_template_usage(service_id, limit_days=None):
 
 @statsd(namespace="dao")
 def dao_get_last_template_usage(template_id):
-    return NotificationHistory.query.filter(
-        NotificationHistory.template_id == template_id,
-        NotificationHistory.key_type != KEY_TYPE_TEST
+    return Notification.query.filter(
+        Notification.template_id == template_id,
+        Notification.key_type != KEY_TYPE_TEST
     ).order_by(
-        desc(NotificationHistory.created_at)
+        desc(Notification.created_at)
     ).first()
 
 

app/template_statistics/rest.py

@@ -7,8 +7,12 @@ from flask import (
 from app import redis_store
 from app.dao.notifications_dao import (
     dao_get_template_usage,
-    dao_get_last_template_usage)
-from app.dao.templates_dao import dao_get_templates_for_cache
+    dao_get_last_template_usage
+)
+from app.dao.templates_dao import (
+    dao_get_templates_for_cache,
+    dao_get_template_by_id_and_service_id
+)
 
 from app.schemas import notification_with_template_schema
 from app.utils import cache_key_for_service_template_counter
@@ -52,12 +56,17 @@ def get_template_statistics_for_service_by_day(service_id):
 
 @template_statistics.route('/<template_id>')
 def get_template_statistics_for_template_id(service_id, template_id):
-    notification = dao_get_last_template_usage(template_id)
-    if not notification:
+    template = dao_get_template_by_id_and_service_id(template_id, service_id)
+    if not template:
         message = 'No template found for id {}'.format(template_id)
         errors = {'template_id': [message]}
         raise InvalidRequest(errors, status_code=404)
+
+    data = None
+    notification = dao_get_last_template_usage(template_id)
+    if notification:
         data = notification_with_template_schema.dump(notification).data
+
     return jsonify(data=data)
 
 

tests/app/template_statistics/test_rest.py

@@ -221,7 +221,24 @@ def test_get_template_statistics_for_template_returns_empty_if_no_statistics(
         headers=[('Content-Type', 'application/json'), auth_header],
     )
 
+    assert response.status_code == 200
+    json_resp = json.loads(response.get_data(as_text=True))
+    assert json_resp['data'] == {}
+
+
+def test_get_template_statistics_raises_error_for_nonexistent_template(
+    client,
+    sample_service,
+    fake_uuid
+):
+    auth_header = create_authorization_header()
+
+    response = client.get(
+        '/service/{}/template-statistics/{}'.format(sample_service.id, fake_uuid),
+        headers=[('Content-Type', 'application/json'), auth_header],
+    )
+
     assert response.status_code == 404
     json_resp = json.loads(response.get_data(as_text=True))
+    assert json_resp['message'] == 'No result found'
     assert json_resp['result'] == 'error'
-    assert json_resp['message']['template_id'] == ['No template found for id {}'.format(sample_template.id)]