遍历关系时，“InstrumentedList”对象没有属性“Location”

Question

我有3个表，在遍历时遇到问题。它们包括一个CAR表、一个位置表和一个CARLOCATION表。汽车保持汽车数据，位置保持位置数据，并且配位数表位于中间，并将汽车链接到其当前位置。

使用Flask和SQLAlchemy，我希望用户能够通过ID搜索汽车，ID通过关系链接到CarLocation表，CarLocation表也通过关系链接到Location表。So Car->；位置->；位置

但是，当我调用Car.CarLocation.Location.Name时，我会收到一个错误，提示：

文件“D:\Documents\GitHub\car\u share\karshare\views.py”，第370行，在searchcar中 CurrentLocation=SearchedCar.CarLocations.Location.Name

AttributeError:“InstrumentedList”对象没有属性“Location”

任何能帮助我的人都是救命恩人

My models.py如下所示：

class Car(db.Model):
    __tablename__ = 'Car'
    __table_args__ = {'schema': 'KarShare'}

    CarID = db.Column(db.Integer, primary_key=True, server_default=db.text(
            "nextval('\"KarShare\".\"Car_CarID_seq\"'::regclass)"))
    Make = db.Column(db.String(64), nullable=False)
    Model = db.Column(db.String(64), nullable=False)
    Year = db.Column(db.Integer, nullable=False)
    Odometer = db.Column(db.Integer, nullable=False)
    CarType = db.Column(db.String(64), nullable=False)
    NumSeats = db.Column(db.Integer, nullable=False)
    FuelType = db.Column(db.String(64), nullable=False)
    CostPerHour = db.Column(db.Float, nullable=False)
    TransmissionType = db.Column(db.String(9), nullable=False)
    Registration = db.Column(db.String(), nullable=False)


class CarLocations(db.Model):
    __tablename__ = 'CarLocations'
    __table_args__ = {'schema': 'KarShare'}

    CarID = db.Column(db.ForeignKey('KarShare.Car.CarID'), primary_key=True,
                      nullable=False)
    CurrentLocationID = db.Column(db.ForeignKey('KarShare.Location.LocationID'),
                                  nullable=True)
    Location = db.relationship("Location", backref="CarLocations",
                               lazy=True)
    Car = db.relationship("Car", backref="CarLocations",lazy=True)


class Location(db.Model):
    __tablename__ = 'Location'
    __table_args__ = {'schema': 'KarShare'}

    LocationID = db.Column(db.Integer, primary_key=True, server_default=db.text(
            "nextval('\"KarShare\".\"Location_LocationID_seq\"'::regclass)"))
    Name = db.Column(db.String(64), index=True, unique=True, nullable=False)
    StreetAddress = db.Column(db.String(128), nullable=False)
    City = db.Column(db.String(64), index=True, nullable=False)
    State = db.Column(db.String(64), index=True, nullable=False)
    Longitude = db.Column(db.Numeric(precision=9, scale=6), nullable=False)
    Latitude = db.Column(db.Numeric(precision=8, scale=6), nullable=False)
    CarSpaces = db.Column(db.Integer, nullable=False)

以及导致错误的简单代码：

     SearchedCar = Car.query.filter_by(CarID=form.search.data).first()
     Make = SearchedCar.Make
     Model = SearchedCar.Model
     Year = SearchedCar.Year
     Odometer = SearchedCar.Odometer
     CarType = SearchedCar.CarType
     NumSeats = SearchedCar.NumSeats
     FuelType = SearchedCar.FuelType
     CostPerHour = SearchedCar.CostPerHour
     TransmissionType = SearchedCar.TransmissionType
     CurrentLocation = SearchedCar.CarLocations.Location.Name
     Registration = SearchedCar.Registration

谢谢你能给我的帮助

Answer 1

Car通过关系有一个CarLocation列表：

- CurrentLocation = SearchedCar.CarLocations.Location.Name
+ if SearchedCar.CarLocations:
+     CurrentLocation = SearchedCar.CarLocations[0].Location.Name