428 lines
17 KiB
Python
428 lines
17 KiB
Python
import functools
|
|
import sys
|
|
import threading
|
|
import warnings
|
|
from collections import Counter, defaultdict
|
|
from functools import partial
|
|
|
|
from django.core.exceptions import AppRegistryNotReady, ImproperlyConfigured
|
|
|
|
from .config import AppConfig
|
|
|
|
|
|
class Apps:
|
|
"""
|
|
A registry that stores the configuration of installed applications.
|
|
|
|
It also keeps track of models, e.g. to provide reverse relations.
|
|
"""
|
|
|
|
def __init__(self, installed_apps=()):
|
|
# installed_apps is set to None when creating the master registry
|
|
# because it cannot be populated at that point. Other registries must
|
|
# provide a list of installed apps and are populated immediately.
|
|
if installed_apps is None and hasattr(sys.modules[__name__], 'apps'):
|
|
raise RuntimeError("You must supply an installed_apps argument.")
|
|
|
|
# Mapping of app labels => model names => model classes. Every time a
|
|
# model is imported, ModelBase.__new__ calls apps.register_model which
|
|
# creates an entry in all_models. All imported models are registered,
|
|
# regardless of whether they're defined in an installed application
|
|
# and whether the registry has been populated. Since it isn't possible
|
|
# to reimport a module safely (it could reexecute initialization code)
|
|
# all_models is never overridden or reset.
|
|
self.all_models = defaultdict(dict)
|
|
|
|
# Mapping of labels to AppConfig instances for installed apps.
|
|
self.app_configs = {}
|
|
|
|
# Stack of app_configs. Used to store the current state in
|
|
# set_available_apps and set_installed_apps.
|
|
self.stored_app_configs = []
|
|
|
|
# Whether the registry is populated.
|
|
self.apps_ready = self.models_ready = self.ready = False
|
|
# For the autoreloader.
|
|
self.ready_event = threading.Event()
|
|
|
|
# Lock for thread-safe population.
|
|
self._lock = threading.RLock()
|
|
self.loading = False
|
|
|
|
# Maps ("app_label", "modelname") tuples to lists of functions to be
|
|
# called when the corresponding model is ready. Used by this class's
|
|
# `lazy_model_operation()` and `do_pending_operations()` methods.
|
|
self._pending_operations = defaultdict(list)
|
|
|
|
# Populate apps and models, unless it's the master registry.
|
|
if installed_apps is not None:
|
|
self.populate(installed_apps)
|
|
|
|
def populate(self, installed_apps=None):
|
|
"""
|
|
Load application configurations and models.
|
|
|
|
Import each application module and then each model module.
|
|
|
|
It is thread-safe and idempotent, but not reentrant.
|
|
"""
|
|
if self.ready:
|
|
return
|
|
|
|
# populate() might be called by two threads in parallel on servers
|
|
# that create threads before initializing the WSGI callable.
|
|
with self._lock:
|
|
if self.ready:
|
|
return
|
|
|
|
# An RLock prevents other threads from entering this section. The
|
|
# compare and set operation below is atomic.
|
|
if self.loading:
|
|
# Prevent reentrant calls to avoid running AppConfig.ready()
|
|
# methods twice.
|
|
raise RuntimeError("populate() isn't reentrant")
|
|
self.loading = True
|
|
|
|
# Phase 1: initialize app configs and import app modules.
|
|
for entry in installed_apps:
|
|
if isinstance(entry, AppConfig):
|
|
app_config = entry
|
|
else:
|
|
app_config = AppConfig.create(entry)
|
|
if app_config.label in self.app_configs:
|
|
raise ImproperlyConfigured(
|
|
"Application labels aren't unique, "
|
|
"duplicates: %s" % app_config.label)
|
|
|
|
self.app_configs[app_config.label] = app_config
|
|
app_config.apps = self
|
|
|
|
# Check for duplicate app names.
|
|
counts = Counter(
|
|
app_config.name for app_config in self.app_configs.values())
|
|
duplicates = [
|
|
name for name, count in counts.most_common() if count > 1]
|
|
if duplicates:
|
|
raise ImproperlyConfigured(
|
|
"Application names aren't unique, "
|
|
"duplicates: %s" % ", ".join(duplicates))
|
|
|
|
self.apps_ready = True
|
|
|
|
# Phase 2: import models modules.
|
|
for app_config in self.app_configs.values():
|
|
app_config.import_models()
|
|
|
|
self.clear_cache()
|
|
|
|
self.models_ready = True
|
|
|
|
# Phase 3: run ready() methods of app configs.
|
|
for app_config in self.get_app_configs():
|
|
app_config.ready()
|
|
|
|
self.ready = True
|
|
self.ready_event.set()
|
|
|
|
def check_apps_ready(self):
|
|
"""Raise an exception if all apps haven't been imported yet."""
|
|
if not self.apps_ready:
|
|
from django.conf import settings
|
|
# If "not ready" is due to unconfigured settings, accessing
|
|
# INSTALLED_APPS raises a more helpful ImproperlyConfigured
|
|
# exception.
|
|
settings.INSTALLED_APPS
|
|
raise AppRegistryNotReady("Apps aren't loaded yet.")
|
|
|
|
def check_models_ready(self):
|
|
"""Raise an exception if all models haven't been imported yet."""
|
|
if not self.models_ready:
|
|
raise AppRegistryNotReady("Models aren't loaded yet.")
|
|
|
|
def get_app_configs(self):
|
|
"""Import applications and return an iterable of app configs."""
|
|
self.check_apps_ready()
|
|
return self.app_configs.values()
|
|
|
|
def get_app_config(self, app_label):
|
|
"""
|
|
Import applications and returns an app config for the given label.
|
|
|
|
Raise LookupError if no application exists with this label.
|
|
"""
|
|
self.check_apps_ready()
|
|
try:
|
|
return self.app_configs[app_label]
|
|
except KeyError:
|
|
message = "No installed app with label '%s'." % app_label
|
|
for app_config in self.get_app_configs():
|
|
if app_config.name == app_label:
|
|
message += " Did you mean '%s'?" % app_config.label
|
|
break
|
|
raise LookupError(message)
|
|
|
|
# This method is performance-critical at least for Django's test suite.
|
|
@functools.lru_cache(maxsize=None)
|
|
def get_models(self, include_auto_created=False, include_swapped=False):
|
|
"""
|
|
Return a list of all installed models.
|
|
|
|
By default, the following models aren't included:
|
|
|
|
- auto-created models for many-to-many relations without
|
|
an explicit intermediate table,
|
|
- models that have been swapped out.
|
|
|
|
Set the corresponding keyword argument to True to include such models.
|
|
"""
|
|
self.check_models_ready()
|
|
|
|
result = []
|
|
for app_config in self.app_configs.values():
|
|
result.extend(app_config.get_models(include_auto_created, include_swapped))
|
|
return result
|
|
|
|
def get_model(self, app_label, model_name=None, require_ready=True):
|
|
"""
|
|
Return the model matching the given app_label and model_name.
|
|
|
|
As a shortcut, app_label may be in the form <app_label>.<model_name>.
|
|
|
|
model_name is case-insensitive.
|
|
|
|
Raise LookupError if no application exists with this label, or no
|
|
model exists with this name in the application. Raise ValueError if
|
|
called with a single argument that doesn't contain exactly one dot.
|
|
"""
|
|
if require_ready:
|
|
self.check_models_ready()
|
|
else:
|
|
self.check_apps_ready()
|
|
|
|
if model_name is None:
|
|
app_label, model_name = app_label.split('.')
|
|
|
|
app_config = self.get_app_config(app_label)
|
|
|
|
if not require_ready and app_config.models is None:
|
|
app_config.import_models()
|
|
|
|
return app_config.get_model(model_name, require_ready=require_ready)
|
|
|
|
def register_model(self, app_label, model):
|
|
# Since this method is called when models are imported, it cannot
|
|
# perform imports because of the risk of import loops. It mustn't
|
|
# call get_app_config().
|
|
model_name = model._meta.model_name
|
|
app_models = self.all_models[app_label]
|
|
if model_name in app_models:
|
|
if (model.__name__ == app_models[model_name].__name__ and
|
|
model.__module__ == app_models[model_name].__module__):
|
|
warnings.warn(
|
|
"Model '%s.%s' was already registered. "
|
|
"Reloading models is not advised as it can lead to inconsistencies, "
|
|
"most notably with related models." % (app_label, model_name),
|
|
RuntimeWarning, stacklevel=2)
|
|
else:
|
|
raise RuntimeError(
|
|
"Conflicting '%s' models in application '%s': %s and %s." %
|
|
(model_name, app_label, app_models[model_name], model))
|
|
app_models[model_name] = model
|
|
self.do_pending_operations(model)
|
|
self.clear_cache()
|
|
|
|
def is_installed(self, app_name):
|
|
"""
|
|
Check whether an application with this name exists in the registry.
|
|
|
|
app_name is the full name of the app e.g. 'django.contrib.admin'.
|
|
"""
|
|
self.check_apps_ready()
|
|
return any(ac.name == app_name for ac in self.app_configs.values())
|
|
|
|
def get_containing_app_config(self, object_name):
|
|
"""
|
|
Look for an app config containing a given object.
|
|
|
|
object_name is the dotted Python path to the object.
|
|
|
|
Return the app config for the inner application in case of nesting.
|
|
Return None if the object isn't in any registered app config.
|
|
"""
|
|
self.check_apps_ready()
|
|
candidates = []
|
|
for app_config in self.app_configs.values():
|
|
if object_name.startswith(app_config.name):
|
|
subpath = object_name[len(app_config.name):]
|
|
if subpath == '' or subpath[0] == '.':
|
|
candidates.append(app_config)
|
|
if candidates:
|
|
return sorted(candidates, key=lambda ac: -len(ac.name))[0]
|
|
|
|
def get_registered_model(self, app_label, model_name):
|
|
"""
|
|
Similar to get_model(), but doesn't require that an app exists with
|
|
the given app_label.
|
|
|
|
It's safe to call this method at import time, even while the registry
|
|
is being populated.
|
|
"""
|
|
model = self.all_models[app_label].get(model_name.lower())
|
|
if model is None:
|
|
raise LookupError(
|
|
"Model '%s.%s' not registered." % (app_label, model_name))
|
|
return model
|
|
|
|
@functools.lru_cache(maxsize=None)
|
|
def get_swappable_settings_name(self, to_string):
|
|
"""
|
|
For a given model string (e.g. "auth.User"), return the name of the
|
|
corresponding settings name if it refers to a swappable model. If the
|
|
referred model is not swappable, return None.
|
|
|
|
This method is decorated with lru_cache because it's performance
|
|
critical when it comes to migrations. Since the swappable settings don't
|
|
change after Django has loaded the settings, there is no reason to get
|
|
the respective settings attribute over and over again.
|
|
"""
|
|
for model in self.get_models(include_swapped=True):
|
|
swapped = model._meta.swapped
|
|
# Is this model swapped out for the model given by to_string?
|
|
if swapped and swapped == to_string:
|
|
return model._meta.swappable
|
|
# Is this model swappable and the one given by to_string?
|
|
if model._meta.swappable and model._meta.label == to_string:
|
|
return model._meta.swappable
|
|
return None
|
|
|
|
def set_available_apps(self, available):
|
|
"""
|
|
Restrict the set of installed apps used by get_app_config[s].
|
|
|
|
available must be an iterable of application names.
|
|
|
|
set_available_apps() must be balanced with unset_available_apps().
|
|
|
|
Primarily used for performance optimization in TransactionTestCase.
|
|
|
|
This method is safe in the sense that it doesn't trigger any imports.
|
|
"""
|
|
available = set(available)
|
|
installed = {app_config.name for app_config in self.get_app_configs()}
|
|
if not available.issubset(installed):
|
|
raise ValueError(
|
|
"Available apps isn't a subset of installed apps, extra apps: %s"
|
|
% ", ".join(available - installed)
|
|
)
|
|
|
|
self.stored_app_configs.append(self.app_configs)
|
|
self.app_configs = {
|
|
label: app_config
|
|
for label, app_config in self.app_configs.items()
|
|
if app_config.name in available
|
|
}
|
|
self.clear_cache()
|
|
|
|
def unset_available_apps(self):
|
|
"""Cancel a previous call to set_available_apps()."""
|
|
self.app_configs = self.stored_app_configs.pop()
|
|
self.clear_cache()
|
|
|
|
def set_installed_apps(self, installed):
|
|
"""
|
|
Enable a different set of installed apps for get_app_config[s].
|
|
|
|
installed must be an iterable in the same format as INSTALLED_APPS.
|
|
|
|
set_installed_apps() must be balanced with unset_installed_apps(),
|
|
even if it exits with an exception.
|
|
|
|
Primarily used as a receiver of the setting_changed signal in tests.
|
|
|
|
This method may trigger new imports, which may add new models to the
|
|
registry of all imported models. They will stay in the registry even
|
|
after unset_installed_apps(). Since it isn't possible to replay
|
|
imports safely (e.g. that could lead to registering listeners twice),
|
|
models are registered when they're imported and never removed.
|
|
"""
|
|
if not self.ready:
|
|
raise AppRegistryNotReady("App registry isn't ready yet.")
|
|
self.stored_app_configs.append(self.app_configs)
|
|
self.app_configs = {}
|
|
self.apps_ready = self.models_ready = self.loading = self.ready = False
|
|
self.clear_cache()
|
|
self.populate(installed)
|
|
|
|
def unset_installed_apps(self):
|
|
"""Cancel a previous call to set_installed_apps()."""
|
|
self.app_configs = self.stored_app_configs.pop()
|
|
self.apps_ready = self.models_ready = self.ready = True
|
|
self.clear_cache()
|
|
|
|
def clear_cache(self):
|
|
"""
|
|
Clear all internal caches, for methods that alter the app registry.
|
|
|
|
This is mostly used in tests.
|
|
"""
|
|
# Call expire cache on each model. This will purge
|
|
# the relation tree and the fields cache.
|
|
self.get_models.cache_clear()
|
|
if self.ready:
|
|
# Circumvent self.get_models() to prevent that the cache is refilled.
|
|
# This particularly prevents that an empty value is cached while cloning.
|
|
for app_config in self.app_configs.values():
|
|
for model in app_config.get_models(include_auto_created=True):
|
|
model._meta._expire_cache()
|
|
|
|
def lazy_model_operation(self, function, *model_keys):
|
|
"""
|
|
Take a function and a number of ("app_label", "modelname") tuples, and
|
|
when all the corresponding models have been imported and registered,
|
|
call the function with the model classes as its arguments.
|
|
|
|
The function passed to this method must accept exactly n models as
|
|
arguments, where n=len(model_keys).
|
|
"""
|
|
# Base case: no arguments, just execute the function.
|
|
if not model_keys:
|
|
function()
|
|
# Recursive case: take the head of model_keys, wait for the
|
|
# corresponding model class to be imported and registered, then apply
|
|
# that argument to the supplied function. Pass the resulting partial
|
|
# to lazy_model_operation() along with the remaining model args and
|
|
# repeat until all models are loaded and all arguments are applied.
|
|
else:
|
|
next_model, *more_models = model_keys
|
|
|
|
# This will be executed after the class corresponding to next_model
|
|
# has been imported and registered. The `func` attribute provides
|
|
# duck-type compatibility with partials.
|
|
def apply_next_model(model):
|
|
next_function = partial(apply_next_model.func, model)
|
|
self.lazy_model_operation(next_function, *more_models)
|
|
apply_next_model.func = function
|
|
|
|
# If the model has already been imported and registered, partially
|
|
# apply it to the function now. If not, add it to the list of
|
|
# pending operations for the model, where it will be executed with
|
|
# the model class as its sole argument once the model is ready.
|
|
try:
|
|
model_class = self.get_registered_model(*next_model)
|
|
except LookupError:
|
|
self._pending_operations[next_model].append(apply_next_model)
|
|
else:
|
|
apply_next_model(model_class)
|
|
|
|
def do_pending_operations(self, model):
|
|
"""
|
|
Take a newly-prepared model and pass it to each function waiting for
|
|
it. This is called at the very end of Apps.register_model().
|
|
"""
|
|
key = model._meta.app_label, model._meta.model_name
|
|
for function in self._pending_operations.pop(key, []):
|
|
function(model)
|
|
|
|
|
|
apps = Apps(installed_apps=None)
|