def add(db_session, data, username):
logger.info(LogMsg.START, username)
schema_validate(data, ADD_SCHEMA_PATH)
logger.debug(LogMsg.SCHEMA_CHECKED)
following_id = data.get('following_id')
user = check_user(username, db_session)
if user is None:
raise Http_error(400, Message.INVALID_USER)
if user.person_id is None:
logger.error(LogMsg.USER_HAS_NO_PERSON, username)
raise Http_error(400, Message.Invalid_persons)
validate_person(user.person_id, db_session)
validate_person(following_id, db_session)
logger.debug(LogMsg.PERSON_EXISTS)
if following_id == user.person_id:
logger.error(LogMsg.FOLLOW_SELF_DENIED)
raise Http_error(400, Message.FOLLOW_DENIED)
logger.debug(LogMsg.FOLLOW_CHECK, data)
follow = get(user.person_id, following_id, db_session)
if follow is not None:
logger.error(LogMsg.FOLLOW_EXISTS, data)
raise Http_error(409, Message.ALREADY_FOLLOWS)
model_instance = Follow()
model_instance.id = str(uuid4())
model_instance.creation_date = Now()
model_instance.creator = username
model_instance.version = 1
model_instance.tags = data.get('tags')
model_instance.following_id = following_id
model_instance.follower_id = user.person_id
db_session.add(model_instance)
logger.debug(LogMsg.FOLLOW_ADD, follow_to_dict(model_instance))
logger.info(LogMsg.END)
return model_instance
