Add get letter contact by id endpoint

Added the GET /<uuid:service_id>/letter-contact/<uuid:letter_contact_id>
endpoint for returning a letter contact for a service with the letter contact id

Added the DAO for returning a letter contact by id

app/dao/service_letter_contact_dao.py

@@ -19,6 +19,16 @@ def dao_get_letter_contacts_by_service_id(service_id):
     return letter_contacts
 
 
+def dao_get_letter_contact_by_id(service_id, letter_contact_id):
+    letter_contact = db.session.query(
+        ServiceLetterContact
+    ).filter(
+        ServiceLetterContact.service_id == service_id,
+        ServiceLetterContact.id == letter_contact_id
+    ).one()
+    return letter_contact
+
+
 def create_or_update_letter_contact(service_id, contact_block):
     letter_contacts = dao_get_letter_contacts_by_service_id(service_id)
     if len(letter_contacts) == 0:

app/service/rest.py

@@ -53,7 +53,11 @@ from app.dao.service_email_reply_to_dao import (
     dao_get_reply_to_by_service_id,
     update_reply_to_email_address
 )
-from app.dao.service_letter_contact_dao import dao_get_letter_contacts_by_service_id, create_or_update_letter_contact
+from app.dao.service_letter_contact_dao import (
+    dao_get_letter_contacts_by_service_id,
+    create_or_update_letter_contact,
+    dao_get_letter_contact_by_id
+)
 from app.dao.provider_statistics_dao import get_fragment_count
 from app.dao.users_dao import get_user_by_id
 from app.errors import (
@@ -577,6 +581,12 @@ def get_letter_contacts(service_id):
     return jsonify([i.serialize() for i in result]), 200
 
 
+@service_blueprint.route('/<uuid:service_id>/letter-contact/<uuid:letter_contact_id>', methods=["GET"])
+def get_letter_contact_by_id(service_id, letter_contact_id):
+    result = dao_get_letter_contact_by_id(service_id=service_id, letter_contact_id=letter_contact_id)
+    return jsonify(result.serialize()), 200
+
+
 @service_blueprint.route('/unique', methods=["GET"])
 def is_service_name_unique():
     name, email_from = check_request_args(request)