[英]Flask SQLAlchemy order_by relationship
我正在使用一個 Flask 應用程序,其中有一個 LargeGroupAttendance model,它引用另一個名為 Attendee 的 model。 我正在嘗試請求符合特定條件的所有 LargeGroupAttendance 對象,但我正在嘗試按參加者 model 的列對它們進行排序 - 這甚至可能嗎? 下面是兩個模型:
""" Attendeee Class """
class Attendee(Base):
__tablename__ = 'attendee'
id = Column(Integer, primary_key=True)
first_name = Column(String(200))
last_name = Column(String(200))
year = Column(String(200))
email = Column(String(100), unique=True)
dorm = Column(String(100))
def __init__(self, first_name, last_name, year, email, dorm):
self.first_name = first_name
self.last_name = last_name
self.year = year
self.email = email
self.dorm = dorm
def __repr__(self):
return '<Attendee %r>' % self.first_name
""" Large Group Attendance Class """
class LargeGroupAttendance(Base):
__tablename__ = 'large_group_attendance'
id = Column(Integer, primary_key=True)
first_time = Column(Integer)
large_group_id = Column(Integer, ForeignKey('large_group.id'))
large_group = relationship("LargeGroup", backref=backref('large_group_attendance', order_by=id))
attendee_id = Column(Integer, ForeignKey('attendee.id'))
attendee = relationship("Attendee", backref=backref('large_group_attendance', order_by=id))
我是否需要向我的與會者 class 添加一些內容才能使這成為可能? 這是我之前嘗試過的查詢,但它沒有 output(也沒有錯誤..)。 我哪里錯了?
attendance_records = db.session.query(LargeGroupAttendance).filter_by(large_group_id=event_id).order_by(desc(LargeGroupAttendance.attendee.first_name))
我認為你需要為你的查詢添加一個連接,如下所示:
.join(LargeGroupAttendance.attendee)
這樣最終的查詢看起來像這樣:
attendance_records = (db.session.query(LargeGroupAttendance).
filter_by(large_group_id = event_id).
join(Attendee, LargeGroupAttendance.attendee).
order_by(desc(Attendee.first_name))
)
請參閱SQLAlchemy:如何在關系字段中排序查詢結果(order_by)? 有關更詳細的解釋
我知道這是一篇舊帖子,但在我搜索時它出現了,所以也許這對其他人有用
""" Attendeee Class """
class Attendee(Base):
__tablename__ = 'attendee'
id = Column(Integer, primary_key=True)
first_name = Column(String(200))
last_name = Column(String(200))
year = Column(String(200))
email = Column(String(100), unique=True)
dorm = Column(String(100))
...
""" Large Group Attendance Class """
class LargeGroupAttendance(Base):
__tablename__ = 'large_group_attendance'
...
attendee_id = Column(Integer, ForeignKey('attendee.id'))
attendee = relationship(
"Attendee",
backref=backref(
'large_group_attendance',
order_by=Attendee.__table__.columns.id
)
)
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