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