Как создать только одну таблицу с SQLAlchemy?

Я не могу создать отдельную таблицу, используя SQLAlchemy.

Я могу создать его, вызвав Base.metadata.create_all(engine), но по мере роста числа таблиц этот вызов занимает много времени.

Я создаю классы таблиц "на лету", а затем заполняю их.

from sqlalchemy import create_engine, Column, Integer, Sequence, String, Date, Float, BIGINT
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

Base = declarative_base()

class HistoricDay():

    id = Column(Integer, Sequence('id_seq'), primary_key=True)
    #  Date, Open, High, Low, Close, Volume, Adj Close
    date = Column(Date)
    open = Column(Float)
    high = Column(Float)
    low = Column(Float)
    close = Column(Float)
    volume = Column(BIGINT)
    adjClose = Column(Float)

    def __init__(self, date, open, high, low, close, volume, adjClose):
        self.date = date
        self.open = open
        self.high = high
        self.low = low
        self.close = close
        self.volume = volume
        self.adjClose = adjClose

def build_daily_history_table_repr(self):
        return "<"+self.__tablename__+"('{}','{}','{}','{}','{}','{}','{}','{}')>".format(self.id, self.date, self.open, self.high, self.low, self.close, self.volume, self.adjClose)

def build_daily_history_table(ticket):
    classname = ticket+"_HistoricDay"
    globals()[classname] = type(classname, (HistoricDay,Base), {'__tablename__' : ticket+"_daily_history"})
    setattr(globals()[classname], '__repr__', build_daily_history_table_repr)

# Initialize the database :: Connection & Metadata retrieval
engine = create_engine('mysql+cymysql://[email protected]/gwc?charset=utf8&use_unicode=0', pool_recycle=3600) # ,echo = True

# SqlAlchemy :: Session setup
Session = sessionmaker(bind=engine)

# Create all tables that do not already exist
Base.metadata.create_all(engine)

# SqlAlchemy :: Starts a session
session = Session()

ticketList = getTicketList()

for ticket in ticketList:
    build_daily_history_table(ticket)
    class_name = ticket+"_HistoricDay"

    meta_create_all_timer = time.time()
    # Create all tables that do not already exist
    # globals()[class_name]('2005-07-24',0,0,0,0,0,0).create(engine)  #doesn't work
    #(globals()[class_name]).__table__.create(engine) #doesn't work
    # session.commit() #doesn't work

    #Base.metadata.create_all(engine) # works but gets very slow
    print("  meta_create_all_timer {}s".format(time.time()-meta_create_all_timer))

    data = getData(ticket)

    for m_date, m_open, m_close, m_high, m_low, m_volume, m_adjClose in data:
        entry = globals()[class_name](m_date, m_open, m_high, m_low, m_close, m_volume, m_adjClose)
        session.add(entry)

    session.commit()

Я видел в документацию, которую вы можете сделать

engine = create_engine('sqlite:///:memory:')

meta = MetaData()

employees = Table('employees', meta,
    Column('employee_id', Integer, primary_key=True),
    Column('employee_name', String(60), nullable=False, key='name'),
    Column('employee_dept', Integer, ForeignKey("departments.department_id"))
)
employees.create(engine)

Однако я не могу понять, как сделать то же самое, что и Table, с declarative_base().

Как я могу это сделать с классами, наследующими от declarative_base()?

Ответы

def build_daily_history_table(ticket):
    classname = ticket + "_HistoricDay"
    ticket = type(classname, (Base, HistoricDay), {'__tablename__' : ticket+"_daily_history"})
    ticket.__repr__ =  build_daily_history_table_repr
    return ticket

build_daily_history_table("test").__table__.create(bind = engine)

2013-10-04 22:36:53,263 INFO sqlalchemy.engine.base.Engine 
CREATE TABLE test_daily_history (
    id INTEGER NOT NULL, 
    date DATE, 
    open FLOAT, 
    high FLOAT, 
    low FLOAT, 
    close FLOAT, 
    volume BIGINT, 
    "adjClose" FLOAT, 
    PRIMARY KEY (id)
)


2013-10-04 22:36:53,263 INFO sqlalchemy.engine.base.Engine ()
2013-10-04 22:36:53,263 INFO sqlalchemy.engine.base.Engine COMMIT

Base.metadata.tables["ticket_daily_history"].create(bind = engine)

Base.metadata.create_all(engine, tables=table_objects)

table_objects = [HistoricDay.__table__]

table_objects = [Base.metadata.tables["historicday"]]

Base.metadata.create_all(db_engine, Base.metadata.tables.values(),checkfirst=True)

Base.metadata.create_all(db_engine, Base.metadata.tables[table_name],checkfirst=True)

from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()
TABLE_PREFIX = "decision_"


class Stock(Base):
    __tablename__ = '{}stocks'.format(TABLE_PREFIX)

    id = Column(Integer, primary_key=True)
    name = Column(String)

class StagePerformance(Base):
    __tablename__ = '{}stage_performance'.format(TABLE_PREFIX)

    id = Column(Integer, primary_key=True)
    date = Column(DateTime)
    stock = relationship("Stock", back_populates="stage_performances")
    period = Column(Integer )
    open = Column(Float)
    high = Column(Float)
    low = Column(Float)
    close = Column(Float)
    change_ratio = Column(Float)
    turnover = Column(Float)
    volume = Column(Float)