On Tue, Feb 6, 2018 at 10:14 AM, <an...@cabine.org> wrote:
> Hello.
>
> I'm using a connection pool backed by SQLAlchemy (1.2.1) to access a
> Postgresql (9.6) server using the psycopg2 (2.7.3.2) driver. I have the
> following pool configuration options set:
>
> from sqlalchemy.dialects import postgresql
> DATABASE_POOL_ARGS = {
> 'max_overflow': 0,
> 'pool_size': 3,
> 'recycle': 3600,
> 'timeout': 10,
> 'pre_ping': True,
> 'dialect': postgresql.dialect(),
> }
>
> Whenever an error occurs during the initial ping I get an exception:
>
> 'NoneType' object has no attribute 'Error'
it is unusual for people to use the pool without an engine like that.
You can always get a pool by creating an engine normally and then
grabbing engine.pool. When the engine is created one of the things
it does is load up the DBAPI for the dialect. if you want to do that
manually, it looks like:
from sqlalchemy import pool
from sqlalchemy.dialects import postgresql
import psycopg2
dialect = postgresql.dialect(dbapi=psycopg2)
DATABASE_POOL_ARGS = {
'max_overflow': 0,
'pool_size': 3,
'recycle': 3600,
'timeout': 10,
'pre_ping': True,
'dialect': dialect
}
def creator():
return psycopg2.connect(user='scott', password='tiger', database='test')
p = pool.QueuePool(creator, **DATABASE_POOL_ARGS)
c = p.connect()
conn = c.connection
c.close()
conn.close()
p.connect()
>
> on line 477 of file sqlalchemy/engine/default.py which is:
>
> except self.dbapi.Error as err:
>
> "self" in this case is an object of type
> "sqlalchemy.dialects.postgresql.psycopg2.PGDialect_psycopg2". Instances of
> this class do not seem to have the "dbapi" attribute, only the class itself
> has it. Should I be passing the class and not an instance for the "dialect"
> option? I've tried that and got a different kind of error:
>
> File "//anaconda/envs/opp/lib/python3.6/site-packages/sqlalchemy/pool.py",
> line 812, in _checkout
> result = pool._dialect.do_ping(fairy.connection)
> TypeError: do_ping() missing 1 required positional argument:
> 'dbapi_connection'
>
> Any help would be appreciated, thanks.
>
> André
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
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