django1/django/db/utils.py

283 lines
8.8 KiB
Python

from functools import wraps
import os
import pkgutil
from threading import local
import warnings
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.utils.functional import cached_property
from django.utils.importlib import import_module
from django.utils.module_loading import import_by_path
from django.utils._os import upath
from django.utils import six
DEFAULT_DB_ALIAS = 'default'
class Error(Exception if six.PY3 else StandardError):
pass
class InterfaceError(Error):
pass
class DatabaseError(Error):
pass
class DataError(DatabaseError):
pass
class OperationalError(DatabaseError):
pass
class IntegrityError(DatabaseError):
pass
class InternalError(DatabaseError):
pass
class ProgrammingError(DatabaseError):
pass
class NotSupportedError(DatabaseError):
pass
class DatabaseErrorWrapper(object):
"""
Context manager and decorator that re-throws 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):
# Under Python 2.6, exc_value can still be a string.
try:
args = tuple(exc_value.args)
except AttributeError:
args = (exc_value,)
dj_exc_value = dj_exc_type(*args)
if six.PY3:
dj_exc_value.__cause__ = exc_value
# 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
six.reraise(dj_exc_type, dj_exc_value, traceback)
def __call__(self, func):
@wraps(func)
def inner(*args, **kwargs):
with self:
return func(*args, **kwargs)
return inner
def load_backend(backend_name):
# Look for a fully qualified database backend name
try:
return import_module('.base', backend_name)
except ImportError as e_user:
# The database backend wasn't found. Display a helpful error message
# listing all possible (built-in) database backends.
backend_dir = os.path.join(os.path.dirname(upath(__file__)), 'backends')
try:
builtin_backends = [
name for _, name, ispkg in pkgutil.iter_modules([backend_dir])
if ispkg and name != 'dummy']
except EnvironmentError:
builtin_backends = []
if backend_name not in ['django.db.backends.%s' % b for b in
builtin_backends]:
backend_reprs = map(repr, sorted(builtin_backends))
error_msg = ("%r isn't an available database backend.\n"
"Try using 'django.db.backends.XXX', where XXX "
"is one of:\n %s\nError was: %s" %
(backend_name, ", ".join(backend_reprs), e_user))
raise ImproperlyConfigured(error_msg)
else:
# If there's some other error, this must be an error in Django
raise
class ConnectionDoesNotExist(Exception):
pass
class ConnectionHandler(object):
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 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):
"""
Puts 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)
if settings.TRANSACTIONS_MANAGED:
warnings.warn(
"TRANSACTIONS_MANAGED is deprecated. Use AUTOCOMMIT instead.",
PendingDeprecationWarning, stacklevel=2)
conn.setdefault('AUTOCOMMIT', 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', 'UTC' if settings.USE_TZ else settings.TIME_ZONE)
for setting in ['NAME', 'USER', 'PASSWORD', 'HOST', 'PORT']:
conn.setdefault(setting, '')
for setting in ['TEST_CHARSET', 'TEST_COLLATION', 'TEST_NAME', 'TEST_MIRROR']:
conn.setdefault(setting, None)
def __getitem__(self, alias):
if hasattr(self._connections, alias):
return getattr(self._connections, alias)
self.ensure_defaults(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]
class ConnectionRouter(object):
def __init__(self, routers=None):
"""
If routers is not specified, will 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, six.string_types):
router = import_by_path(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
try:
return hints['instance']._state.db or DEFAULT_DB_ALIAS
except KeyError:
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_syncdb(self, db, model):
for router in self.routers:
try:
method = router.allow_syncdb
except AttributeError:
# If the router doesn't have a method, skip to the next one.
pass
else:
allow = method(db, model)
if allow is not None:
return allow
return True