批量保存复杂对象SQLAlchemy

Question

association_table = Table("association_table",
                          Base.metadata,
                          Column("show_id", Integer(), ForeignKey("show_times.id"), primary_key=True),
                          Column("theater_id", Integer(), ForeignKey("theaters.id")))

association_table2 = Table("association_table2",
                           Base.metadata,
                           Column("show_id", Integer(), ForeignKey("show_times.id"), primary_key=True),
                           Column("movie_id", Integer(), ForeignKey("movies.id")))



class Movie(Base):
    __tablename__ = "movies"
    id = Column(Integer, primary_key=True)
    title = Column(String(), unique=True)
    plot = Column(String())
    duration = Column(String())
    rating = Column(String())
    trailer = Column(String())
    imdb = Column(String())
    poster = Column(String())
    summary = Column(String())

class Theater(Base):
    __tablename__ = "theaters"
    id = Column(Integer, primary_key=True)
    zip_code = Column(String())
    city = Column(String())
    state = Column(String())
    address = Column(String())
    phone_number = Column(String())


class Showtime(Base):
    __tablename__ = "show_times"
    id = Column(Integer, primary_key=True)
    date = Column(Date())
    theaterz = relationship("Theater", secondary=association_table)
    moviez = relationship("Movie", secondary=association_table2)
    showtimes = Column(String())

假设我们有电影对象:

movie_1 = Movie(title="Cap Murica",
              plot="Cap punches his way to freedom",
              duration="2 hours")

movie_2 = Movie(title="Cap Murica 22222",
              plot="Cap punches his way to freedom again",
              duration="2 hours")

和戏剧对象:

theater = Theater(name="Regal Cinemas",
                  zip_code="00000",
                  city="Houston",
                  state="TX")

我们如何将其大量保存到show_times模型中？

我试过这样做:

movies = [movie_1, movie_2] # these movie objects are from the code snippet above

show_times = Showtime(date="5/19/2016",
                      theaterz=[theater],
                      moviez=movies)
session.add(show_times)
session.commit()

欢呼上述作品.但是当我这样批量做的时候:

showtime_lists = [show_time1, show_time2, showtime3] # these are basically just the same show time objects as above

session.bulk_save_objects(showtime_lists)
session.commit()

它不会失败,但数据也不会持久存储到数据库中.

我的意思是,是否可以show_time单独添加每个会话？批量插入会更好,但我不明白为什么数据不会持久化,如果这样做.

Answer 1

Session.bulk_save_objects()对于您的用例而言,它是一个太低级别的API,它持久存在多个模型对象及其关系.文档清楚如下:

警告

批量保存功能允许以大多数其他工作单元功能为代价的行的低延迟INSERT/UPDATE.默认情况下,将忽略对象管理,关系处理和SQL子句支持等功能,以支持原始的INSERT/UPDATES记录.

在使用此方法之前,请阅读批量操作的警告列表,并完全测试并确认使用这些系统开发的所有代码的功能.

您应该使用Session.add_all()向会话添加实例集合.它将一次处理一个实例,但这是您必须为高级功能(如关系处理)支付的价格.

所以,而不是

session.bulk_save_objects(showtime_lists)
session.commit()

做

session.add_all(showtime_lists)
session.commit()