Python 如何使用SQLAlchemy建立表之间的关系？

使用SQLAlchemy，给定如下表：

locations_table = Table('locations', metadata,
    Column('id',        Integer, primary_key=True),
    Column('name', Text),
)

players_table = Table('players', metadata,
    Column('id',                 Integer, primary_key=True),
    Column('email',           Text),
    Column('password',   Text),
    Column('location_id',  ForeignKey('locations.id'))
)

class Location(object):
    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return '<Location: %s, %s>' % (self.name)

mapper(Location, locations_table)

class Player(object):
    def __init__(self, email, password, location_id):
        self.email = email
        self.password = password
        self.location_id = location_id

    def __repr__(self):
        return '<Player: %s>' % self.email

mapper(Player, players_table)

# assign location to player using a Location object, as opposed to an ID
player.location = location
# access the Location object associated with the player directly
print player.location.name

以及以下类别：

locations_table = Table('locations', metadata,
    Column('id',        Integer, primary_key=True),
    Column('name', Text),
)

players_table = Table('players', metadata,
    Column('id',                 Integer, primary_key=True),
    Column('email',           Text),
    Column('password',   Text),
    Column('location_id',  ForeignKey('locations.id'))
)

class Location(object):
    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return '<Location: %s, %s>' % (self.name)

mapper(Location, locations_table)

class Player(object):
    def __init__(self, email, password, location_id):
        self.email = email
        self.password = password
        self.location_id = location_id

    def __repr__(self):
        return '<Player: %s>' % self.email

mapper(Player, players_table)

# assign location to player using a Location object, as opposed to an ID
player.location = location
# access the Location object associated with the player directly
print player.location.name

简化的

我将如何修改它以支持以下操作：

locations_table = Table('locations', metadata,
    Column('id',        Integer, primary_key=True),
    Column('name', Text),
)

players_table = Table('players', metadata,
    Column('id',                 Integer, primary_key=True),
    Column('email',           Text),
    Column('password',   Text),
    Column('location_id',  ForeignKey('locations.id'))
)

class Location(object):
    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return '<Location: %s, %s>' % (self.name)

mapper(Location, locations_table)

class Player(object):
    def __init__(self, email, password, location_id):
        self.email = email
        self.password = password
        self.location_id = location_id

    def __repr__(self):
        return '<Player: %s>' % self.email

mapper(Player, players_table)

# assign location to player using a Location object, as opposed to an ID
player.location = location
# access the Location object associated with the player directly
print player.location.name

如果炼金术允许：

# print all players having a certain location
print location.players

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？使用sqlalchemy的关系功能：

---

使用sqlalchemy的关系功能：

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这应该适合您：

mapperPlayer，players\u表，属性={'location'=relationLocation，uselist=False，backref=backref'players'}

---

这样您就可以直接访问该位置，因为您不会得到列表。除此之外，您还可以执行location.players，它将返回一个InstrumentedList，这样您就可以对播放器进行测试，这应该对您有用：

mapperPlayer，players\u表，属性={'location'=relationLocation，uselist=False，backref=backref'players'}

这样您就可以直接访问该位置，因为您不会得到列表。除此之外，您还可以执行location.players，它将返回一个InstrumentedList，这样您就可以对播放器进行测试