• Language: en

Source code for django.db.utils

import os
import pkgutil
from importlib import import_module
from threading import local

from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.utils.functional import cached_property
from django.utils.module_loading import import_string

DEFAULT_DB_ALIAS = 'default'
DJANGO_VERSION_PICKLE_KEY = '_django_version'

[docs]class Error(Exception): pass
[docs]class InterfaceError(Error): pass
[docs]class DatabaseError(Error): pass
[docs]class DataError(DatabaseError): pass
[docs]class OperationalError(DatabaseError): pass
[docs]class IntegrityError(DatabaseError): pass
[docs]class InternalError(DatabaseError): pass
[docs]class ProgrammingError(DatabaseError): pass
[docs]class NotSupportedError(DatabaseError): pass
class DatabaseErrorWrapper: """ Context manager and decorator that reraises backend-specific database exceptions using Django's common wrappers. """ def __init__(self, wrapper): """ wrapper is a database wrapper. It must have a Database attribute defining PEP-249 exceptions. """ self.wrapper = wrapper def __enter__(self): pass def __exit__(self, exc_type, exc_value, traceback): if exc_type is None: return for dj_exc_type in ( DataError, OperationalError, IntegrityError, InternalError, ProgrammingError, NotSupportedError, DatabaseError, InterfaceError, Error, ): db_exc_type = getattr(self.wrapper.Database, dj_exc_type.__name__) if issubclass(exc_type, db_exc_type): dj_exc_value = dj_exc_type(*exc_value.args) # Only set the 'errors_occurred' flag for errors that may make # the connection unusable. if dj_exc_type not in (DataError, IntegrityError): self.wrapper.errors_occurred = True raise dj_exc_value.with_traceback(traceback) from exc_value def __call__(self, func): # Note that we are intentionally not using @wraps here for performance # reasons. Refs #21109. def inner(*args, **kwargs): with self: return func(*args, **kwargs) return inner def load_backend(backend_name): """ Return a database backend's "base" module given a fully qualified database backend name, or raise an error if it doesn't exist. """ # This backend was renamed in Django 1.9. if backend_name == 'django.db.backends.postgresql_psycopg2': backend_name = 'django.db.backends.postgresql' try: return import_module('%s.base' % backend_name) except ImportError as e_user: # The database backend wasn't found. Display a helpful error message # listing all built-in database backends. backend_dir = os.path.join(os.path.dirname(__file__), 'backends') builtin_backends = [ name for _, name, ispkg in pkgutil.iter_modules([backend_dir]) if ispkg and name not in {'base', 'dummy', 'postgresql_psycopg2'} ] if backend_name not in ['django.db.backends.%s' % b for b in builtin_backends]: backend_reprs = map(repr, sorted(builtin_backends)) raise ImproperlyConfigured( "%r isn't an available database backend.\n" "Try using 'django.db.backends.XXX', where XXX is one of:\n" " %s" % (backend_name, ", ".join(backend_reprs)) ) from e_user else: # If there's some other error, this must be an error in Django raise class ConnectionDoesNotExist(Exception): pass class ConnectionHandler: def __init__(self, databases=None): """ databases is an optional dictionary of database definitions (structured like settings.DATABASES). """ self._databases = databases self._connections = local() @cached_property def databases(self): if self._databases is None: self._databases = settings.DATABASES if self._databases == {}: self._databases = { DEFAULT_DB_ALIAS: { 'ENGINE': 'django.db.backends.dummy', }, } if self._databases[DEFAULT_DB_ALIAS] == {}: self._databases[DEFAULT_DB_ALIAS]['ENGINE'] = 'django.db.backends.dummy' if DEFAULT_DB_ALIAS not in self._databases: raise ImproperlyConfigured("You must define a '%s' database" % DEFAULT_DB_ALIAS) return self._databases def ensure_defaults(self, alias): """ Put the defaults into the settings dictionary for a given connection where no settings is provided. """ try: conn = self.databases[alias] except KeyError: raise ConnectionDoesNotExist("The connection %s doesn't exist" % alias) conn.setdefault('ATOMIC_REQUESTS', False) conn.setdefault('AUTOCOMMIT', True) conn.setdefault('ENGINE', 'django.db.backends.dummy') if conn['ENGINE'] == 'django.db.backends.' or not conn['ENGINE']: conn['ENGINE'] = 'django.db.backends.dummy' conn.setdefault('CONN_MAX_AGE', 0) conn.setdefault('OPTIONS', {}) conn.setdefault('TIME_ZONE', None) for setting in ['NAME', 'USER', 'PASSWORD', 'HOST', 'PORT']: conn.setdefault(setting, '') def prepare_test_settings(self, alias): """ Make sure the test settings are available in the 'TEST' sub-dictionary. """ try: conn = self.databases[alias] except KeyError: raise ConnectionDoesNotExist("The connection %s doesn't exist" % alias) test_settings = conn.setdefault('TEST', {}) for key in ['CHARSET', 'COLLATION', 'NAME', 'MIRROR']: test_settings.setdefault(key, None) def __getitem__(self, alias): if hasattr(self._connections, alias): return getattr(self._connections, alias) self.ensure_defaults(alias) self.prepare_test_settings(alias) db = self.databases[alias] backend = load_backend(db['ENGINE']) conn = backend.DatabaseWrapper(db, alias) setattr(self._connections, alias, conn) return conn def __setitem__(self, key, value): setattr(self._connections, key, value) def __delitem__(self, key): delattr(self._connections, key) def __iter__(self): return iter(self.databases) def all(self): return [self[alias] for alias in self] def close_all(self): for alias in self: try: connection = getattr(self._connections, alias) except AttributeError: continue connection.close() class ConnectionRouter: def __init__(self, routers=None): """ If routers is not specified, default to settings.DATABASE_ROUTERS. """ self._routers = routers @cached_property def routers(self): if self._routers is None: self._routers = settings.DATABASE_ROUTERS routers = [] for r in self._routers: if isinstance(r, str): router = import_string(r)() else: router = r routers.append(router) return routers def _router_func(action): def _route_db(self, model, **hints): chosen_db = None for router in self.routers: try: method = getattr(router, action) except AttributeError: # If the router doesn't have a method, skip to the next one. pass else: chosen_db = method(model, **hints) if chosen_db: return chosen_db instance = hints.get('instance') if instance is not None and instance._state.db: return instance._state.db return DEFAULT_DB_ALIAS return _route_db db_for_read = _router_func('db_for_read') db_for_write = _router_func('db_for_write') def allow_relation(self, obj1, obj2, **hints): for router in self.routers: try: method = router.allow_relation except AttributeError: # If the router doesn't have a method, skip to the next one. pass else: allow = method(obj1, obj2, **hints) if allow is not None: return allow return obj1._state.db == obj2._state.db def allow_migrate(self, db, app_label, **hints): for router in self.routers: try: method = router.allow_migrate except AttributeError: # If the router doesn't have a method, skip to the next one. continue allow = method(db, app_label, **hints) if allow is not None: return allow return True def allow_migrate_model(self, db, model): return self.allow_migrate( db, model._meta.app_label, model_name=model._meta.model_name, model=model, ) def get_migratable_models(self, app_config, db, include_auto_created=False): """Return app models allowed to be migrated on provided db.""" models = app_config.get_models(include_auto_created=include_auto_created) return [model for model in models if self.allow_migrate_model(db, model)]
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