Allow users to set postage per precompiled letter

app/notifications/process_letter_notifications.py

@@ -20,6 +20,7 @@ def create_letter_notification(letter_data, template, api_key, status, reply_to_
         client_reference=letter_data.get('reference'),
         status=status,
         reply_to_text=reply_to_text,
-        billable_units=billable_units
+        billable_units=billable_units,
+        postage=letter_data.get('postage')
     )
     return notification

app/notifications/process_notifications.py

@@ -75,7 +75,8 @@ def persist_notification(
     created_by_id=None,
     status=NOTIFICATION_CREATED,
     reply_to_text=None,
-    billable_units=None
+    billable_units=None,
+    postage=None
 ):
     notification_created_at = created_at or datetime.utcnow()
     if not notification_id:
@@ -112,11 +113,14 @@ def persist_notification(
     elif notification_type == EMAIL_TYPE:
         notification.normalised_to = format_email_address(notification.to)
     elif notification_type == LETTER_TYPE:
-        template = dao_get_template_by_id(template_id, template_version)
-        if service.has_permission(CHOOSE_POSTAGE) and template.postage:
-            notification.postage = template.postage
+        if postage:
+            notification.postage = postage
         else:
-            notification.postage = service.postage
+            template = dao_get_template_by_id(template_id, template_version)
+            if service.has_permission(CHOOSE_POSTAGE) and template.postage:
+                notification.postage = template.postage
+            else:
+                notification.postage = service.postage
 
     # if simulated create a Notification model to return but do not persist the Notification to the dB
     if not simulated:

app/v2/notifications/notification_schemas.py

@@ -239,7 +239,8 @@ post_precompiled_letter_request = {
     "title": "POST v2/notifications/letter",
     "properties": {
         "reference": {"type": "string"},
-        "content": {"type": "string"}
+        "content": {"type": "string"},
+        "postage": {"type": "string"}
     },
     "required": ["reference", "content"],
     "additionalProperties": False