#models.py
class Question(db.Model):
    text = db.Column('text', db.String)

class Choice(db.Model):
    text = db.Column('text', db.String)
    q_id = db.Column('q_id', db.Integer, db.ForeignKey(Question.id))
    question = db.relationship('Question', foreign_keys=q_id)


#services.py
class QuestionService(object):
    def __init__(self, question_repository, choice_repository):
        self.question_repository = question_repository
        self.choice_repository = choice_repository

    def create_question(self, payload):
        try:
            question = models.Question(text = payload['question'])
            question = self.question_repository.create(question)
            self.create_choices(payload['choices'], question.id)
            db.session.commit()
        except SQLALchemyError:
            db.session.rollback()

    def create_choices(self, choices, question_id):
        choices = [ models.Choice(text=choice_text, q_id=question_id)
                    for choice_text in choices ]
        self.choice_repository.create_all(choices)

    def fetch_by_text(self, text):
        #called from views.py
        return self.question_repository.fetch_by_text(text)

    def fetch_by_id(self, id):
        #called from views.py
        question = self.question_repository.fetch(id)
        if not question:
            raise ResourceNotFound()
        return question


#repositories.py
from models import db
class BaseRepository(object):
    def __init__(self, db=None):
        self.db = db

    def create(self, item):
        self.db.session.add(item)
        self.db.session.flush()
        return item

    def create_all(self, item):
        self.db.session.add_all(item)
        self.db.session.flush()
        return item

class QuestionRepository(BaseRepository):
    def fetch(self, id):
        return self.session.query(Question).filter(Question.id == id).first()

    def fetch_by_text(self, text):
        return self.session.query(Question).filter(Question.text == text).all()

class ChoiceRepository(BaseRepository):
    pass