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- import inspect
- import types
- from collections import defaultdict
- from itertools import chain
-
- from django.apps import apps
- from django.conf import settings
- from django.core.checks import Error, Tags, Warning, register
-
-
- @register(Tags.models)
- def check_all_models(app_configs=None, **kwargs):
- db_table_models = defaultdict(list)
- errors = []
- if app_configs is None:
- models = apps.get_models()
- else:
- models = chain.from_iterable(app_config.get_models() for app_config in app_configs)
- for model in models:
- if model._meta.managed and not model._meta.proxy:
- db_table_models[model._meta.db_table].append(model._meta.label)
- if not inspect.ismethod(model.check):
- errors.append(
- Error(
- "The '%s.check()' class method is currently overridden by %r."
- % (model.__name__, model.check),
- obj=model,
- id='models.E020'
- )
- )
- else:
- errors.extend(model.check(**kwargs))
- if settings.DATABASE_ROUTERS:
- error_class, error_id = Warning, 'models.W035'
- error_hint = (
- 'You have configured settings.DATABASE_ROUTERS. Verify that %s '
- 'are correctly routed to separate databases.'
- )
- else:
- error_class, error_id = Error, 'models.E028'
- error_hint = None
- for db_table, model_labels in db_table_models.items():
- if len(model_labels) != 1:
- model_labels_str = ', '.join(model_labels)
- errors.append(
- error_class(
- "db_table '%s' is used by multiple models: %s."
- % (db_table, model_labels_str),
- obj=db_table,
- hint=(error_hint % model_labels_str) if error_hint else None,
- id=error_id,
- )
- )
- return errors
-
-
- def _check_lazy_references(apps, ignore=None):
- """
- Ensure all lazy (i.e. string) model references have been resolved.
-
- Lazy references are used in various places throughout Django, primarily in
- related fields and model signals. Identify those common cases and provide
- more helpful error messages for them.
-
- The ignore parameter is used by StateApps to exclude swappable models from
- this check.
- """
- pending_models = set(apps._pending_operations) - (ignore or set())
-
- # Short circuit if there aren't any errors.
- if not pending_models:
- return []
-
- from django.db.models import signals
- model_signals = {
- signal: name for name, signal in vars(signals).items()
- if isinstance(signal, signals.ModelSignal)
- }
-
- def extract_operation(obj):
- """
- Take a callable found in Apps._pending_operations and identify the
- original callable passed to Apps.lazy_model_operation(). If that
- callable was a partial, return the inner, non-partial function and
- any arguments and keyword arguments that were supplied with it.
-
- obj is a callback defined locally in Apps.lazy_model_operation() and
- annotated there with a `func` attribute so as to imitate a partial.
- """
- operation, args, keywords = obj, [], {}
- while hasattr(operation, 'func'):
- # The or clauses are redundant but work around a bug (#25945) in
- # functools.partial in Python <= 3.5.1.
- args.extend(getattr(operation, 'args', []) or [])
- keywords.update(getattr(operation, 'keywords', {}) or {})
- operation = operation.func
- return operation, args, keywords
-
- def app_model_error(model_key):
- try:
- apps.get_app_config(model_key[0])
- model_error = "app '%s' doesn't provide model '%s'" % model_key
- except LookupError:
- model_error = "app '%s' isn't installed" % model_key[0]
- return model_error
-
- # Here are several functions which return CheckMessage instances for the
- # most common usages of lazy operations throughout Django. These functions
- # take the model that was being waited on as an (app_label, modelname)
- # pair, the original lazy function, and its positional and keyword args as
- # determined by extract_operation().
-
- def field_error(model_key, func, args, keywords):
- error_msg = (
- "The field %(field)s was declared with a lazy reference "
- "to '%(model)s', but %(model_error)s."
- )
- params = {
- 'model': '.'.join(model_key),
- 'field': keywords['field'],
- 'model_error': app_model_error(model_key),
- }
- return Error(error_msg % params, obj=keywords['field'], id='fields.E307')
-
- def signal_connect_error(model_key, func, args, keywords):
- error_msg = (
- "%(receiver)s was connected to the '%(signal)s' signal with a "
- "lazy reference to the sender '%(model)s', but %(model_error)s."
- )
- receiver = args[0]
- # The receiver is either a function or an instance of class
- # defining a `__call__` method.
- if isinstance(receiver, types.FunctionType):
- description = "The function '%s'" % receiver.__name__
- elif isinstance(receiver, types.MethodType):
- description = "Bound method '%s.%s'" % (receiver.__self__.__class__.__name__, receiver.__name__)
- else:
- description = "An instance of class '%s'" % receiver.__class__.__name__
- signal_name = model_signals.get(func.__self__, 'unknown')
- params = {
- 'model': '.'.join(model_key),
- 'receiver': description,
- 'signal': signal_name,
- 'model_error': app_model_error(model_key),
- }
- return Error(error_msg % params, obj=receiver.__module__, id='signals.E001')
-
- def default_error(model_key, func, args, keywords):
- error_msg = "%(op)s contains a lazy reference to %(model)s, but %(model_error)s."
- params = {
- 'op': func,
- 'model': '.'.join(model_key),
- 'model_error': app_model_error(model_key),
- }
- return Error(error_msg % params, obj=func, id='models.E022')
-
- # Maps common uses of lazy operations to corresponding error functions
- # defined above. If a key maps to None, no error will be produced.
- # default_error() will be used for usages that don't appear in this dict.
- known_lazy = {
- ('django.db.models.fields.related', 'resolve_related_class'): field_error,
- ('django.db.models.fields.related', 'set_managed'): None,
- ('django.dispatch.dispatcher', 'connect'): signal_connect_error,
- }
-
- def build_error(model_key, func, args, keywords):
- key = (func.__module__, func.__name__)
- error_fn = known_lazy.get(key, default_error)
- return error_fn(model_key, func, args, keywords) if error_fn else None
-
- return sorted(filter(None, (
- build_error(model_key, *extract_operation(func))
- for model_key in pending_models
- for func in apps._pending_operations[model_key]
- )), key=lambda error: error.msg)
-
-
- @register(Tags.models)
- def check_lazy_references(app_configs=None, **kwargs):
- return _check_lazy_references(apps)
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