[Sqlalchemy-tickets] Issue #3088: Sqlalchemy: possible bug when inserting rows and returning the primary key (zzzeek/sqlalchemy)

[lfiaschi <iss...@bi...>]

New issue 3088: Sqlalchemy: possible bug when inserting rows and returning the primary key
https://bitbucket.org/zzzeek/sqlalchemy/issue/3088/sqlalchemy-possible-bug-when-inserting

lfiaschi:

Hi, 
I noticed something strange when inserting multiple rows and returning the primary keys. 
If I add use the parameter values in the isert query I get the expected behaviour, hower when passing the values to the cursor, nothing is returned.

Is it possibly a bug?

My sqlachemy version is 0.9.4, below how to reproduce the error:




```
#!python

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!
```

The error is 


```
#!

Traceback (most recent call last):
  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


```