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Я создал простое приложение Pyramid, которое использует SQLAlchemy, pyramid_tm, pyramid_beaker и alembic. База данных - PostgreSQL, а адаптер - pg8000. Теперь я пытаюсь внедрить логин, но первый запрос БД к базе данных создает транзакцию BEGIN и вешает навсегда. Я хотел бы настроить транзакции только при необходимости (UPDATE, DELETE, INSERT и более сложные многозадачные запросы).Как не начинать транзакцию автоматически в Pyramid?
models/user.py:
from sqlalchemy import Column
from sqlalchemy import Unicode
from sqlalchemy import Sequence
from sqlalchemy import Integer
from sqlalchemy import Index
from sqlalchemy import CheckConstraint
from sqlalchemy import text
from sqlalchemy import func
from sqlalchemy.dialects.postgresql import TIMESTAMP
from pyramid.security import Allow
import sqlalchemy.orm.exc as a_exc
import logging
log = logging.getLogger(__name__)
from ..models import DBSession
from ..models import Base
class UserNotFoundException(ValueError):
pass
class User(Base):
__tablename__ = 'users'
__table_args__ = (
CheckConstraint("login ~* '^[a-z]{3,}$'", name = __tablename__ + "_chk_login"),
CheckConstraint("login != ''", name = __tablename__ + "_chk_login_not_empty"),
CheckConstraint("password != ''", name = __tablename__ + "_chk_pw_not_empty"),
Index(__tablename__ + "_idx_lower_login", text("lower(login)"), unique = True),
)
id = Column(Integer, Sequence('users_id_seq'), primary_key = True)
login = Column(Unicode(64), unique = True, nullable = False, server_default = text("''"))
password = Column(Unicode(255), nullable = False, server_default = text("''"))
added = Column(TIMESTAMP, nullable = False, server_default = text("NOW()"))
@property
def __acl__(self):
return [(Allow, self.login, 'view'), ]
def __init__(self, login, password):
self.login = login
self.password = password
@classmethod
def get_user(self, login):
try:
u = DBSession.query(User).filter(User.login == login).one()
DBSession.flush()
return u
except a_exc.NoResultFound as exc:
raise UserNotFoundException(exc)
@classmethod
def get_user_count(self):
u = DBSession.query(func.count(User.id)).scalar()
DBSession.flush()
return u
@classmethod
def create_session(self, login: str, password: str) -> object:
u = self.get_user(login)
import bcrypt
password = password.encode('utf-8')
try:
verified = bcrypt.checkpw(password = password, hashed_password = u.password.encode('utf-8'))
except Exception as exc:
raise
if verified != True:
raise Exception("Coulnd't verify password hash")
return {'userid': u.id}
@classmethod
def add_user(self, login, password):
import bcrypt
password = password.encode('utf-8')
encrypted_pw = bcrypt.hashpw(password, bcrypt.gensalt())
verified = False
log.debug("Encrypted PW: '%s'", encrypted_pw)
try:
verified = bcrypt.checkpw(password = password, hashed_password = encrypted_pw)
except Exception:
raise
if verified != True:
raise Exception("Coulnd't verify password hash")
try:
DBSession.begin(subtransactions=True)
DBSession.add(User(login = login, password = encrypted_pw.decode()))
DBSession.commit()
log.debug("User added: '%s'", login)
except Exception as exc:
DBSession.rollback()
log.debug("User add failed for user '%s'", login)
raise
views/views.py:
@view_config(route_name = 'login', renderer = 'templates/login.pt')
def app_login_view(request: Request):
if request.authenticated_userid:
# Already logged in -> redirect
import pyramid.httpexceptions as exc
return exc.HTTPFound(request.route_path('home'))
user_not_found_error = {
'page_background': 'warning',
'page_title': _(u"Login failed"),
'page_text': _(u"Check username and password."),
}
form_user = request.POST.get('user')
form_password = request.POST.get('password')
from ..models import User, UserNotFoundException
if User.get_user_count() == 0:
# No users in DB
log.debug("Creating admin user")
User.add_user(u"admin", u"admin")
try:
ses = User.create_session(form_user, form_password)
request.session['userid'] = ses['userid']
request.session.save()
remember(request, ses['userid'])
except UserNotFoundException as exc:
log.debug("User '%s' not found in database", form_user)
return user_not_found_error
except:
raise
# Redirect to front page
import pyramid.httpexceptions as exc
return exc.HTTPFound(request.route_path('home'))
Вход:
INFO sqlalchemy.engine.base.Engine.dbconn BEGIN (implicit)
INFO sqlalchemy.engine.base.Engine.dbconn SELECT count(users.id) AS count_1
FROM users
INFO sqlalchemy.engine.base.Engine.dbconn()
DEBUG [waitress] Creating admin user
DEBUG [user][waitress] Encrypted PW: 'b'$2b$12$n6mN973Gz0wwX7B0kWI.Ae099h7mvLo.mEI.D2NFjZKaLKbGebK16''
INFO sqlalchemy.engine.base.Engine.dbconn INSERT INTO users (id, login, password) VALUES (nextval('users_id_seq'), %s, %s) RETURNING users.id
INFO sqlalchemy.engine.base.Engine.dbconn ('admin', '$2b$12$n6mN973Gz0wwX7B0kWI.Ae099h7mvLo.mEI.D2NFjZKaLKbGebK16')
INFO [sqlalchemy.engine.base.Engine.dbconn:109][waitress] INSERT INTO users (id, login, password) VALUES (nextval('users_id_seq'), %s, %s) RETURNING users.id
INFO [sqlalchemy.engine.base.Engine.dbconn:109][waitress] ('admin', '$2b$12$n6mN973Gz0wwX7B0kWI.Ae099h7mvLo.mEI.D2NFjZKaLKbGebK16')
... Hangs here forever ...
Если удалить subtransactions=True из add_user() я получаю:
sqlalchemy.exc.InvalidRequestError: A transaction is already begun. Use subtransactions=True to allow subtransactions.
Кроме того, когда я отправляю к /login я вижу переменные сессии в закладке Request Vars в DebugToolbar с _accessed_time и _creation_time, но ничего о ID_пользователе и после редиректа на / нет никаких переменных сессии вообще.
Вы не должны делиться сеансом SQLAlchemy между запросами. Создайте (и впоследствии уничтожите) новую «сессию» для каждого запроса. – univerio