Mi aplicación se conecta a múltiples bases de datos usando una técnica similar a this. Funciona siempre que no intente acceder a diferentes bases de datos en la misma solicitud. Después de examinar de nuevo a la secuencia de comandos que veo que han escrito un comentario para este fin:¿Cómo puedo usar varias bases de datos en la misma solicitud en Cherrypy y SQLAlchemy?
SQLAlchemy integration for CherryPy,
such that you can access multiple databases,
but only one of these databases per request or thread.
Mi aplicación ahora me requiere para obtener los datos de la base de datos Una base de datos y B. ¿Es posible hacer esto en una sola petición ?
favor ver más abajo para las fuentes y ejemplos:
Ejemplo de Trabajo 1:
from model import meta
my_object_instance = meta.main_session().query(MyObject).filter(
MyObject.id == 1
).one()
de Trabajo Ejemplo 2:
from model import meta
my_user = meta.user_session().query(User).filter(
User.id == 1
).one()
Error Ejemplo:
from model import meta
my_object_instance = meta.main_session().query(MyObject).filter(
MyObject.id == 1
).one()
my_user = meta.user_session().query(User).filter(
User.id == 1
).one()
Este errores con:
(sqlalchemy.exc.ProgrammingError) (1146, "Table 'main_db.user' doesn't exist")
Fuentes:
# meta.py
import cherrypy
import sqlalchemy
from sqlalchemy import MetaData
from sqlalchemy.orm import scoped_session, sessionmaker
from sqlalchemy.ext.declarative import declarative_base
# Return an Engine
def create_engine(defaultschema = True, schema = "", **kwargs):
# A blank DB is the same as no DB so to specify a non-schema-specific connection just override with defaultschema = False
connectionString = 'mysql://%s:%[email protected]%s/%s?charset=utf8' % (
store['application'].config['main']['database-server-config-username'],
store['application'].config['main']['database-server-config-password'],
store['application'].config['main']['database-server-config-host'],
store['application'].config['main']['database-server-config-defaultschema'] if defaultschema else schema
)
# Create engine object. we pass **kwargs through so this call can be extended
return sqlalchemy.create_engine(connectionString, echo=True, pool_recycle=10, echo_pool=True, encoding='utf-8', **kwargs)
# Engines
main_engine = create_engine()
user_engine = None
# Sessions
_main_session = None
_user_session = None
# Metadata
main_metadata = MetaData()
main_metadata.bind = main_engine
user_metadata = MetaData()
# No idea what bases are/do but nothing works without them
main_base = declarative_base(metadata = main_metadata)
user_base = declarative_base(metadata = user_metadata)
# An easy collection of user database connections
engines = {}
# Each thread gets a session based on this object
GlobalSession = scoped_session(sessionmaker(autoflush=True, autocommit=False, expire_on_commit=False))
def main_session():
_main_session = cherrypy.request.main_dbsession
_main_session.configure(bind=main_engine)
return _main_session
def user_session():
_user_session = cherrypy.request.user_dbsession
_user_session.configure(bind = get_user_engine())
return _user_session
def get_user_engine():
# Get dburi from the users instance
dburi = cherrypy.session['auth']['user'].instance.database
# Store this engine for future use
if dburi in engines:
engine = engines.get(dburi)
else:
engine = engines[dburi] = create_engine(defaultschema = False, schema = dburi)
# Return Engine
return engine
def get_user_metadata():
user_metadata.bind = get_user_engine()
return user_metadata
# open a new session for the life of the request
def open_dbsession():
cherrypy.request.user_dbsession = cherrypy.thread_data.scoped_session_class
cherrypy.request.main_dbsession = cherrypy.thread_data.scoped_session_class
return
# close the session for this request
def close_dbsession():
if hasattr(cherrypy.request, "user_dbsession"):
try:
cherrypy.request.user_dbsession.flush()
cherrypy.request.user_dbsession.remove()
del cherrypy.request.user_dbsession
except:
pass
if hasattr(cherrypy.request, "main_dbsession"):
try:
cherrypy.request.main_dbsession.flush()
cherrypy.request.main_dbsession.remove()
del cherrypy.request.main_dbsession
except:
pass
return
# initialize the session factory class for the selected thread
def connect(thread_index):
cherrypy.thread_data.scoped_session_class = scoped_session(sessionmaker(autoflush=True, autocommit=False))
return
# add the hooks to cherrypy
cherrypy.tools.dbsession_open = cherrypy.Tool('on_start_resource', open_dbsession)
cherrypy.tools.dbsession_close = cherrypy.Tool('on_end_resource', close_dbsession)
cherrypy.engine.subscribe('start_thread', connect)
No quiero 'responder' mi propia pregunta pero la solución parece ser agregar una scoped_session extra para la otra base de datos en 'connect' para que parezca' def connect (thread_index): cherrypy.thread_data.user_scoped_session_class = scoped_session (sessionmaker (autoflush = True, autocommit = False)) cherrypy.thread_data.main_scoped_session_class = scoped_session (sessionmaker (autoflush = True, autocommit = False)) return' y luego los referencia por separado en 'open_dbsession' – OrganicPanda