Add a column for a service to set SMS prefixing

In future changes, services will be able to control whether their text
messages will be prefixed with the name of their service.

This commit:
- adds a column to store the value of that setting
- makes the service model take notice of it, if it were to have a value
  set

It doesn’t:
- provide a way of setting the value of this column

Currently the column can have three values:
- `None` – ignore it (this is what all current services will start as)
  and continue to determine whether to prefix messages by looking at the
  sender
- `True` – always the service name to the start of text messages
- `False` – never add the service name to the start of text messages

In the future we’ll migrate all services to be either `True` or `False`,
the `None` will go away and all services will have direct control over
the setting.

app/delivery/send_to_providers.py

@@ -48,7 +48,7 @@ def send_sms_to_provider(notification):
         )
         template_model = dao_get_template_by_id(notification.template_id, notification.template_version)
 
-        sender_has_been_customised = (not service.prefix_sms_with_service_name())
+        sender_has_been_customised = (not service.get_prefix_sms_with_service_name())
 
         template = SMSMessageTemplate(
             template_model.__dict__,

app/models.py

@@ -224,6 +224,7 @@ class Service(db.Model, Versioned):
     _reply_to_email_address = db.Column("reply_to_email_address", db.Text, index=False, unique=False, nullable=True)
     _letter_contact_block = db.Column('letter_contact_block', db.Text, index=False, unique=False, nullable=True)
     sms_sender = db.Column(db.String(11), nullable=False, default=lambda: current_app.config['FROM_NUMBER'])
+    prefix_sms = db.Column(db.Boolean, nullable=True)
     organisation_id = db.Column(UUID(as_uuid=True), db.ForeignKey('organisation.id'), index=True, nullable=True)
     free_sms_fragment_limit = db.Column(db.BigInteger, index=False, unique=False, nullable=True)
     organisation = db.relationship('Organisation')
@@ -280,7 +281,9 @@ class Service(db.Model, Versioned):
         default_letter_contact = [x for x in self.letter_contacts if x.is_default]
         return default_letter_contact[0].contact_block if default_letter_contact else None
 
-    def prefix_sms_with_service_name(self):
+    def get_prefix_sms_with_service_name(self):
+        if self.prefix_sms is not None:
+            return self.prefix_sms
         return self.get_default_sms_sender() == current_app.config['FROM_NUMBER']
 
 

app/schemas.py

@@ -203,7 +203,7 @@ class ServiceSchema(BaseSchema):
         return service.get_default_letter_contact()
 
     def get_prefix_sms_with_service_name(self, service):
-        return service.prefix_sms_with_service_name()
+        return service.get_prefix_sms_with_service_name()
 
     class Meta:
         model = models.Service