Flask-SQLAlchemy关系错误

Question

我正在建立一个与Flask和SQLAlchemy的应用程序接口，并已创建了2个表之间的关系。当我运行项目时，所有的工作似乎都很好，当通过python manage.py test运行时，测试也可以工作，但是如果我使用PyTest命令或通过PyCharm运行测试，那么它会抛出初始化映射器的错误。关系是能够使用teams名称获取Search对象上的所有SearchTeams

错误是：

sqlalchemy.exc.InvalidRequestError: When initializing mapper mapped class Search->searches, expression 'SearchTeam' failed to locate a name ('SearchTeam'). If this is a class name, consider adding this relationship() to the <class 'app.models.Search.Search'> class after both dependent classes have been defined.

这些模型包括：

搜索：

class Search(db.Model):
    __tablename__ = 'searches'

    id = db.Column(db.Integer, primary_key=True)
    uuid = db.Column(UUID(as_uuid=True), unique=True, nullable=False, default=uuid.uuid4)
    location = db.Column(db.String(255), nullable=False)
    date = db.Column(db.Date, default=datetime.today)
    start_time = db.Column(db.String(10), nullable=False)
    end_time = db.Column(db.String(10), nullable=True)
    type = db.Column(db.String(255))
    oic = db.Column(db.String(255))
    sm = db.Column(db.String(255))
    so = db.Column(db.String(255))
    sl = db.Column(db.String(255))
    ro = db.Column(db.String(255))
    scribe = db.Column(db.String(255))
    notes = db.Column(db.Text)

    teams = db.relationship('SearchTeam', backref='search')

    def __init__(self, location, date, start_time, type, oic, sm, so, sl, ro, scribe):
        self.location = location
        self.date = date
        self.start_time = start_time
        self.type = type
        self.oic = oic
        self.sm = sm
        self.so = so
        self.sl = sl
        self.ro = ro
        self.scribe = scribe

SearchTeam：

class SearchTeam(db.Model):
    __tablename__ = 'search_teams'

    id = db.Column(db.Integer, primary_key=True)
    uuid = db.Column(UUID(as_uuid=True), unique=True, nullable=False, default=uuid.uuid4)
    search_id = db.Column(db.Integer, db.ForeignKey('searches.id'))
    team_leader = db.Column(db.String(255), nullable=False)
    medic = db.Column(db.String(255), nullable=False)
    responder_1 = db.Column(db.String(255), nullable=True)
    responder_2 = db.Column(db.String(255), nullable=True)
    responder_3 = db.Column(db.String(255), nullable=True)

    def __init__(self, search, team_leader, medic, responder_1, responder_2, responder_3):
        self.search = search
        self.team_leader = team_leader
        self.medic = medic
        self.responder_1 = responder_1
        self.responder_2 = responder_2
        self.responder_3 = responder_3

Answer 1

在深入研究之后，我能够通过简单地将SearchTeam模型导入到Search模型中来实现这一点。

不是100%确定为什么/如何修复它，因为我使用过类似关系的其他项目不需要这样做，但它现在起作用了，这是主要的事情。

Answer 2

你可以将backref改为'searches‘。另请参阅https://docs.sqlalchemy.org/en/13/orm/backref.html

teams = db.relationship('SearchTeam', backref='search')