There was a misunderstanding about how we wanted the feature to work.

There is no need for the extra column.
If a template does not have a default address set - they address will be blank.
Otherwise use the address of the service_letter_contact.

There will be another PR to do a db migration.
Template.service_letter_contact = blank if no service_letter_contacts for service ELSE use set Template.serivce_letter_contact_id = service default service_letter_contact

app/models.py

@@ -582,10 +582,6 @@ class TemplateBase(db.Model):
     content = db.Column(db.Text, nullable=False)
     archived = db.Column(db.Boolean, nullable=False, default=False)
     subject = db.Column(db.Text)
-    is_letter_contact_blank = db.Column(db.Boolean, nullable=False, default=False)
-
-    # if is_letter_contact = True then service_letter_contact must be null.
-    CheckConstraint("Not(is_letter_contact_blank = True and service_letter_contact_id is not Null)")
 
     @declared_attr
     def service_id(cls):

migrations/versions/0154_revert_0153.py

@@ -0,0 +1,20 @@
+"""
+
+Revision ID: 0154_revert_0153
+Revises: 0153_add_is_letter_contact_blank
+Create Date: 2018-01-05 14:09:21.200102
+
+"""
+from alembic import op
+
+revision = '0154_revert_0153'
+down_revision = '0153_add_is_letter_contact_blank'
+
+
+def upgrade():
+    op.drop_column('templates', 'is_letter_contact_blank')
+    op.drop_column('templates_history', 'is_letter_contact_blank')
+
+
+def downgrade():
+    pass

tests/app/template/test_rest.py

@@ -625,7 +625,6 @@ def test_get_template_reply_to(client, sample_letter_template):
     assert 'service_letter_contact_id' not in json_resp['data']
     assert json_resp['data']['reply_to'] == str(letter_contact.id)
     assert json_resp['data']['reply_to_text'] == letter_contact.contact_block
-    assert not json_resp['data']['is_letter_contact_blank']
 
 
 def test_update_template_reply_to(client, sample_letter_template):