Question

插入多行并返回主键时，我注意到一些奇怪的事情。如果我在isert查询中添加使用参数值，我会得到预期的行为，但是当将值传递给游标时，不会返回任何内容。

这可能是一个错误，还是我误解了什么？

我的sqlachemy版本是0.9.4，低于如何重现错误：

from sqlalchemy import create_engine, Column, Unicode, DateTime
from sqlalchemy import Float, ForeignKey, BigInteger, Enum, Integer, Boolean
from sqlalchemy.orm import relationship, sessionmaker
from sqlalchemy.ext.declarative import declarative_base


cmd= 'postgresql+psycopg2://lfiaschi:mypswd@localhost:5432/test_db'

Base = declarative_base()

class Test(Base):
    __tablename__ = 'test'
    db_id = Column(BigInteger, primary_key=True, autoincrement=True)
    name = Column(Unicode(255), nullable=False)


engine=create_engine(cmd, encoding='utf8', implicit_returning=False)
Base.metadata.drop_all(engine)
Base.metadata.create_all(engine)


N=10
rows = [{'name': str(i)} for i in range(N)]

#If the values are specified at this point the primary keys seem correctly returned
ins_statement1 = Test.__table__.insert(returning=[Test.__table__.c.db_id]).values(rows)

connection = engine.connect()


res1 = connection.execute(ins_statement1)
correct_ids = res1.fetchall()
print correct_ids
assert len(correct_ids) == N


ins_statement1 = Test.__table__.insert(returning=[Test.__table__.c.db_id])

#If we specify the values here
res2 = connection.execute(ins_statement1,rows)

res2.fetchall() #BOOOM!

我得到的错误是：

 File "bug_sqlalchemy.py", line 42, in <module>
    res2.fetchall() #BOOOM!
  File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/sqlalchemy/engine/result.py", line 788, in fetchall
    self.cursor, self.context)
  File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1108, in _handle_dbapi_exception
    exc_info
  File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 185, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb)
  File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/sqlalchemy/engine/result.py", line 782, in fetchall
    l = self.process_rows(self._fetchall_impl())
  File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/sqlalchemy/engine/result.py", line 749, in _fetchall_impl
    return self.cursor.fetchall()
sqlalchemy.exc.ProgrammingError: (ProgrammingError) no results to fetch None None

有人能解释一下这个区别吗？

重新插入插入行的主键的最合适方法是什么？

插入多行并返回主键时Sqlalchemy奇怪的行为

0 个答案: