Question

我觉得我要完成的查询不是太复杂，但是在尝试之后，我感觉有点迷茫。

我在测验应用程序中使用三种模型：

用户-具有“测验”属性，该属性与“测验”表有关系

测验-具有“问题”属性，该属性与“问题”表有关系。

问题-具有布尔值的“正确”属性。

对于我的查询，我想返回给定用户正确回答了多少个问题。我对SQLAlchemy的掌握并不特别，令人困惑的是模型关系链。

这是我的模特代码：

class Question(db.Model):
""" Question object that will be a part of a Quiz's question_list

    Attributes:
        key - word/item to be tested from subject dictionary
        answer - correct answer generated via Quiz.type_method
        definition - word definition from subject dict
        question - question_string created by quiz.Quiz
"""

__tablename__ = 'questions'

question_id = db.Column('id', db.Integer, primary_key=True)
key = db.Column(db.String)
answer = db.Column(db.String)
definition = db.Column(db.String)
question = db.Column(db.String)
correct = db.Column(db.Boolean)
quiz_id = db.Column(db.Integer, db.ForeignKey('quizzes.id'))

quiz = db.relationship('Quiz', back_populates='questions')

def __repr__(self):
    return (f"<Question(key='{self.key}', answer='{self.answer}', "
            f"definition='{self.definition}', question='{self.question}', "
            f"correct={self.correct}, quiz_id={self.quiz_id})>")


class Quiz(db.Model):
    __tablename__ = 'quizzes'

    quiz_id = db.Column('id', db.Integer, primary_key=True)
    category = db.Column(db.String, nullable=False)
    quiz_type = db.Column('type', db.String, nullable=False)
    taken_on = db.Column(db.String,
                         default=datetime.utcnow().isoformat(' ', 'seconds'))
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))

    questions = db.relationship('Question', order_by=Question.question_id,
                                back_populates='quiz')
    user = db.relationship('User', back_populates='quizzes')

    @property
    def num_correct(self):
        return len([q for q in self.questions if q.correct])

    @property
    def num_wrong(self):
        return len(self.questions) - self.num_correct

    @property
    def questions_asked(self):
        return self.num_correct + self.num_wrong

    @property
    def questions_remaining(self):
        return self.length - (self.num_correct + self.num_wrong)

    @property
    def score_percent(self):
        return round(self.num_correct / self.questions_asked, 2)

    def results(self):
        """ Return formatted string summary of quiz results """

        return 'You got {} question{} correct and {} question{} wrong.'.format(
            self.num_correct, '' if self.num_correct == 1 else 's',
            self.num_wrong, '' if self.num_wrong == 1 else 's')

    # can use string formatting for title case
    def __str__(self):
        """ Return quiz_string for printing based on quiz_specs """

        if self.quiz_type == 'definition':
            return f'{self.category} {self.quiz_type} quiz'
        else:
            return f'{self.quiz_type} tense {self.category} quiz'

    def __repr__(self):
        return (f"<Quiz(category='{self.category}', "
                f"quiz_type='{self.quiz_type}', quiz_id={self.quiz_id}, "
                f"taken_on={self.taken_on})>")


# TODO: add admin column
class User(db.Model, UserMixin):
    __tablename__ = 'users'

    id = db.Column('id', db.Integer, primary_key=True)
    username = db.Column(db.String, unique=True, nullable=False)
    email = db.Column(db.String(120), index=True, unique=True)
    password_hash = db.Column(db.String(128))
    # db.String because sqlite has no DateTime type isoformat='YYYY-MM-DD'
    created_on = db.Column(db.String,
                           default=datetime.utcnow().isoformat(' ', 'seconds'))
    # num_correct , num_wrong

    quizzes = db.relationship('Quiz', order_by=Quiz.quiz_id,
                              back_populates='user')

如果可以提供更好的上下文，请使用github链接：

full code

我真的被困在这里。即使在正确方向上的一点也将受到极大的赞赏。

无法使用flask-sqlalchemy找出更深入的查询

0 个答案: