def construct_backend(backend_type=None):
"""
Construct a concrete backend instance based on the backend_type or use the global backend value if not specified.
:param backend_type: get a backend instance based on the specified type (or default)
:return: :class:`Backend`
"""
if backend_type is None:
from aiida.backends import settings
backend_type = settings.BACKEND
if backend_type == 'django':
global _DJANGO_BACKEND
if _DJANGO_BACKEND is None:
from aiida.orm.implementation.django.backend import DjangoBackend
_DJANGO_BACKEND = DjangoBackend()
return _DJANGO_BACKEND
elif backend_type == 'sqlalchemy':
global _SQLA_BACKEND
if _SQLA_BACKEND is None:
from aiida.orm.implementation.sqlalchemy.backend import SqlaBackend
_SQLA_BACKEND = SqlaBackend()
return _SQLA_BACKEND
else:
raise ValueError(
"The specified backend {} is currently not implemented".format(
backend_type))
def _load_backend(self, schema_check=True):
"""Load the backend for the currently configured profile and return it.
.. note:: this will reconstruct the `Backend` instance in `self._backend` so the preferred method to load the
backend is to call `get_backend` which will create it only when not yet instantiated.
:param schema_check: force a database schema check if the database environment has not yet been loaded
:return: the database backend
:rtype: :class:`aiida.orm.implementation.Backend`
"""
from aiida.backends import BACKEND_DJANGO, BACKEND_SQLA
from aiida.common import ConfigurationError, InvalidOperation
from aiida.common.log import configure_logging
from aiida.manage import configuration
profile = self.get_profile()
if profile is None:
raise ConfigurationError(
'Could not determine the current profile. Consider loading a profile using `aiida.load_profile()`.'
)
if configuration.BACKEND_UUID is not None and configuration.BACKEND_UUID != profile.uuid:
raise InvalidOperation(
'cannot load backend because backend of another profile is already loaded'
)
backend_type = profile.database_backend
if backend_type == BACKEND_DJANGO:
from aiida.backends.djsite.utils import load_dbenv, _load_dbenv_noschemacheck
load_backend = load_dbenv if schema_check else _load_dbenv_noschemacheck
elif backend_type == BACKEND_SQLA:
from aiida.backends.sqlalchemy.utils import load_dbenv, _load_dbenv_noschemacheck
load_backend = load_dbenv if schema_check else _load_dbenv_noschemacheck
else:
raise ConfigurationError(
'Invalid backend type {} in profile: {}'.format(
backend_type, profile.name))
# Do NOT reload the backend environment if already loaded, simply reload the backend instance after
if configuration.BACKEND_UUID is None:
load_backend(profile)
configuration.BACKEND_UUID = profile.uuid
# Can only import the backend classes after the backend has been loaded
if backend_type == BACKEND_DJANGO:
from aiida.orm.implementation.django.backend import DjangoBackend
self._backend = DjangoBackend()
elif backend_type == BACKEND_SQLA:
from aiida.orm.implementation.sqlalchemy.backend import SqlaBackend
self._backend = SqlaBackend()
# Reconfigure the logging with `with_orm=True` to make sure that profile specific logging configuration options
# are taken into account and the `DbLogHandler` is configured.
configure_logging(with_orm=True)
return self._backend
def setUpClass_method(self):
self.clean_db()
self.backend = DjangoBackend()