607 lines
25 KiB
Python
607 lines
25 KiB
Python
import copy
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from contextlib import contextmanager
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from django.apps import AppConfig
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from django.apps.registry import Apps, apps as global_apps
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from django.conf import settings
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from django.db import models
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from django.db.models.fields.related import RECURSIVE_RELATIONSHIP_CONSTANT
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from django.db.models.options import DEFAULT_NAMES, normalize_together
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from django.db.models.utils import make_model_tuple
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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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from django.utils.version import get_docs_version
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from .exceptions import InvalidBasesError
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def _get_app_label_and_model_name(model, app_label=''):
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if isinstance(model, str):
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split = model.split('.', 1)
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return tuple(split) if len(split) == 2 else (app_label, split[0])
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else:
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return model._meta.app_label, model._meta.model_name
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def _get_related_models(m):
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"""Return all models that have a direct relationship to the given model."""
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related_models = [
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subclass for subclass in m.__subclasses__()
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if issubclass(subclass, models.Model)
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]
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related_fields_models = set()
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for f in m._meta.get_fields(include_parents=True, include_hidden=True):
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if f.is_relation and f.related_model is not None and not isinstance(f.related_model, str):
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related_fields_models.add(f.model)
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related_models.append(f.related_model)
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# Reverse accessors of foreign keys to proxy models are attached to their
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# concrete proxied model.
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opts = m._meta
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if opts.proxy and m in related_fields_models:
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related_models.append(opts.concrete_model)
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return related_models
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def get_related_models_tuples(model):
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"""
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Return a list of typical (app_label, model_name) tuples for all related
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models for the given model.
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"""
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return {
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(rel_mod._meta.app_label, rel_mod._meta.model_name)
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for rel_mod in _get_related_models(model)
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}
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def get_related_models_recursive(model):
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"""
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Return all models that have a direct or indirect relationship
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to the given model.
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Relationships are either defined by explicit relational fields, like
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ForeignKey, ManyToManyField or OneToOneField, or by inheriting from another
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model (a superclass is related to its subclasses, but not vice versa). Note,
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however, that a model inheriting from a concrete model is also related to
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its superclass through the implicit *_ptr OneToOneField on the subclass.
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"""
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seen = set()
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queue = _get_related_models(model)
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for rel_mod in queue:
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rel_app_label, rel_model_name = rel_mod._meta.app_label, rel_mod._meta.model_name
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if (rel_app_label, rel_model_name) in seen:
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continue
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seen.add((rel_app_label, rel_model_name))
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queue.extend(_get_related_models(rel_mod))
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return seen - {(model._meta.app_label, model._meta.model_name)}
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class ProjectState:
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"""
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Represent the entire project's overall state. This is the item that is
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passed around - do it here rather than at the app level so that cross-app
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FKs/etc. resolve properly.
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"""
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def __init__(self, models=None, real_apps=None):
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self.models = models or {}
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# Apps to include from main registry, usually unmigrated ones
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self.real_apps = real_apps or []
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self.is_delayed = False
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def add_model(self, model_state):
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app_label, model_name = model_state.app_label, model_state.name_lower
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self.models[(app_label, model_name)] = model_state
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if 'apps' in self.__dict__: # hasattr would cache the property
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self.reload_model(app_label, model_name)
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def remove_model(self, app_label, model_name):
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del self.models[app_label, model_name]
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if 'apps' in self.__dict__: # hasattr would cache the property
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self.apps.unregister_model(app_label, model_name)
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# Need to do this explicitly since unregister_model() doesn't clear
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# the cache automatically (#24513)
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self.apps.clear_cache()
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def _find_reload_model(self, app_label, model_name, delay=False):
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if delay:
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self.is_delayed = True
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related_models = set()
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try:
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old_model = self.apps.get_model(app_label, model_name)
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except LookupError:
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pass
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else:
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# Get all relations to and from the old model before reloading,
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# as _meta.apps may change
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if delay:
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related_models = get_related_models_tuples(old_model)
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else:
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related_models = get_related_models_recursive(old_model)
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# Get all outgoing references from the model to be rendered
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model_state = self.models[(app_label, model_name)]
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# Directly related models are the models pointed to by ForeignKeys,
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# OneToOneFields, and ManyToManyFields.
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direct_related_models = set()
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for field in model_state.fields.values():
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if field.is_relation:
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if field.remote_field.model == RECURSIVE_RELATIONSHIP_CONSTANT:
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continue
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rel_app_label, rel_model_name = _get_app_label_and_model_name(field.related_model, app_label)
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direct_related_models.add((rel_app_label, rel_model_name.lower()))
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# For all direct related models recursively get all related models.
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related_models.update(direct_related_models)
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for rel_app_label, rel_model_name in direct_related_models:
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try:
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rel_model = self.apps.get_model(rel_app_label, rel_model_name)
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except LookupError:
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pass
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else:
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if delay:
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related_models.update(get_related_models_tuples(rel_model))
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else:
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related_models.update(get_related_models_recursive(rel_model))
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# Include the model itself
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related_models.add((app_label, model_name))
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return related_models
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def reload_model(self, app_label, model_name, delay=False):
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if 'apps' in self.__dict__: # hasattr would cache the property
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related_models = self._find_reload_model(app_label, model_name, delay)
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self._reload(related_models)
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def reload_models(self, models, delay=True):
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if 'apps' in self.__dict__: # hasattr would cache the property
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related_models = set()
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for app_label, model_name in models:
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related_models.update(self._find_reload_model(app_label, model_name, delay))
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self._reload(related_models)
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def _reload(self, related_models):
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# Unregister all related models
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with self.apps.bulk_update():
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for rel_app_label, rel_model_name in related_models:
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self.apps.unregister_model(rel_app_label, rel_model_name)
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states_to_be_rendered = []
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# Gather all models states of those models that will be rerendered.
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# This includes:
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# 1. All related models of unmigrated apps
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for model_state in self.apps.real_models:
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if (model_state.app_label, model_state.name_lower) in related_models:
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states_to_be_rendered.append(model_state)
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# 2. All related models of migrated apps
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for rel_app_label, rel_model_name in related_models:
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try:
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model_state = self.models[rel_app_label, rel_model_name]
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except KeyError:
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pass
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else:
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states_to_be_rendered.append(model_state)
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# Render all models
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self.apps.render_multiple(states_to_be_rendered)
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def clone(self):
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"""Return an exact copy of this ProjectState."""
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new_state = ProjectState(
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models={k: v.clone() for k, v in self.models.items()},
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real_apps=self.real_apps,
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)
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if 'apps' in self.__dict__:
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new_state.apps = self.apps.clone()
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new_state.is_delayed = self.is_delayed
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return new_state
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def clear_delayed_apps_cache(self):
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if self.is_delayed and 'apps' in self.__dict__:
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del self.__dict__['apps']
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@cached_property
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def apps(self):
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return StateApps(self.real_apps, self.models)
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@property
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def concrete_apps(self):
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self.apps = StateApps(self.real_apps, self.models, ignore_swappable=True)
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return self.apps
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@classmethod
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def from_apps(cls, apps):
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"""Take an Apps and return a ProjectState matching it."""
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app_models = {}
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for model in apps.get_models(include_swapped=True):
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model_state = ModelState.from_model(model)
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app_models[(model_state.app_label, model_state.name_lower)] = model_state
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return cls(app_models)
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def __eq__(self, other):
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return self.models == other.models and set(self.real_apps) == set(other.real_apps)
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class AppConfigStub(AppConfig):
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"""Stub of an AppConfig. Only provides a label and a dict of models."""
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# Not used, but required by AppConfig.__init__
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path = ''
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def __init__(self, label):
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self.label = label
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# App-label and app-name are not the same thing, so technically passing
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# in the label here is wrong. In practice, migrations don't care about
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# the app name, but we need something unique, and the label works fine.
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super().__init__(label, None)
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def import_models(self):
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self.models = self.apps.all_models[self.label]
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class StateApps(Apps):
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"""
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Subclass of the global Apps registry class to better handle dynamic model
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additions and removals.
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"""
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def __init__(self, real_apps, models, ignore_swappable=False):
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# Any apps in self.real_apps should have all their models included
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# in the render. We don't use the original model instances as there
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# are some variables that refer to the Apps object.
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# FKs/M2Ms from real apps are also not included as they just
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# mess things up with partial states (due to lack of dependencies)
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self.real_models = []
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for app_label in real_apps:
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app = global_apps.get_app_config(app_label)
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for model in app.get_models():
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self.real_models.append(ModelState.from_model(model, exclude_rels=True))
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# Populate the app registry with a stub for each application.
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app_labels = {model_state.app_label for model_state in models.values()}
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app_configs = [AppConfigStub(label) for label in sorted([*real_apps, *app_labels])]
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super().__init__(app_configs)
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# These locks get in the way of copying as implemented in clone(),
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# which is called whenever Django duplicates a StateApps before
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# updating it.
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self._lock = None
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self.ready_event = None
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self.render_multiple([*models.values(), *self.real_models])
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# There shouldn't be any operations pending at this point.
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from django.core.checks.model_checks import _check_lazy_references
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ignore = {make_model_tuple(settings.AUTH_USER_MODEL)} if ignore_swappable else set()
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errors = _check_lazy_references(self, ignore=ignore)
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if errors:
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raise ValueError("\n".join(error.msg for error in errors))
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@contextmanager
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def bulk_update(self):
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# Avoid clearing each model's cache for each change. Instead, clear
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# all caches when we're finished updating the model instances.
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ready = self.ready
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self.ready = False
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try:
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yield
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finally:
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self.ready = ready
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self.clear_cache()
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def render_multiple(self, model_states):
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# We keep trying to render the models in a loop, ignoring invalid
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# base errors, until the size of the unrendered models doesn't
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# decrease by at least one, meaning there's a base dependency loop/
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# missing base.
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if not model_states:
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return
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# Prevent that all model caches are expired for each render.
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with self.bulk_update():
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unrendered_models = model_states
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while unrendered_models:
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new_unrendered_models = []
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for model in unrendered_models:
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try:
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model.render(self)
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except InvalidBasesError:
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new_unrendered_models.append(model)
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if len(new_unrendered_models) == len(unrendered_models):
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raise InvalidBasesError(
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"Cannot resolve bases for %r\nThis can happen if you are inheriting models from an "
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"app with migrations (e.g. contrib.auth)\n in an app with no migrations; see "
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"https://docs.djangoproject.com/en/%s/topics/migrations/#dependencies "
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"for more" % (new_unrendered_models, get_docs_version())
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)
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unrendered_models = new_unrendered_models
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def clone(self):
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"""Return a clone of this registry."""
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clone = StateApps([], {})
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clone.all_models = copy.deepcopy(self.all_models)
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clone.app_configs = copy.deepcopy(self.app_configs)
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# Set the pointer to the correct app registry.
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for app_config in clone.app_configs.values():
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app_config.apps = clone
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# No need to actually clone them, they'll never change
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clone.real_models = self.real_models
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return clone
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def register_model(self, app_label, model):
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self.all_models[app_label][model._meta.model_name] = model
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if app_label not in self.app_configs:
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self.app_configs[app_label] = AppConfigStub(app_label)
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self.app_configs[app_label].apps = self
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self.app_configs[app_label].models = {}
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self.app_configs[app_label].models[model._meta.model_name] = model
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self.do_pending_operations(model)
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self.clear_cache()
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def unregister_model(self, app_label, model_name):
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try:
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del self.all_models[app_label][model_name]
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del self.app_configs[app_label].models[model_name]
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except KeyError:
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pass
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class ModelState:
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"""
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Represent a Django Model. Don't use the actual Model class as it's not
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designed to have its options changed - instead, mutate this one and then
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render it into a Model as required.
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Note that while you are allowed to mutate .fields, you are not allowed
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to mutate the Field instances inside there themselves - you must instead
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assign new ones, as these are not detached during a clone.
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"""
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def __init__(self, app_label, name, fields, options=None, bases=None, managers=None):
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self.app_label = app_label
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self.name = name
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self.fields = dict(fields)
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self.options = options or {}
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self.options.setdefault('indexes', [])
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self.options.setdefault('constraints', [])
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self.bases = bases or (models.Model,)
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self.managers = managers or []
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for name, field in self.fields.items():
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# Sanity-check that fields are NOT already bound to a model.
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if hasattr(field, 'model'):
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raise ValueError(
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'ModelState.fields cannot be bound to a model - "%s" is.' % name
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)
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# Sanity-check that relation fields are NOT referring to a model class.
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if field.is_relation and hasattr(field.related_model, '_meta'):
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raise ValueError(
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'ModelState.fields cannot refer to a model class - "%s.to" does. '
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'Use a string reference instead.' % name
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)
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if field.many_to_many and hasattr(field.remote_field.through, '_meta'):
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raise ValueError(
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'ModelState.fields cannot refer to a model class - "%s.through" does. '
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'Use a string reference instead.' % name
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)
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# Sanity-check that indexes have their name set.
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for index in self.options['indexes']:
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if not index.name:
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raise ValueError(
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"Indexes passed to ModelState require a name attribute. "
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"%r doesn't have one." % index
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)
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@cached_property
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def name_lower(self):
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return self.name.lower()
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@classmethod
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def from_model(cls, model, exclude_rels=False):
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"""Given a model, return a ModelState representing it."""
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# Deconstruct the fields
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fields = []
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for field in model._meta.local_fields:
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if getattr(field, "remote_field", None) and exclude_rels:
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continue
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if isinstance(field, models.OrderWrt):
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continue
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name = field.name
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try:
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fields.append((name, field.clone()))
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except TypeError as e:
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raise TypeError("Couldn't reconstruct field %s on %s: %s" % (
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name,
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model._meta.label,
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e,
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))
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if not exclude_rels:
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for field in model._meta.local_many_to_many:
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name = field.name
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try:
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fields.append((name, field.clone()))
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except TypeError as e:
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raise TypeError("Couldn't reconstruct m2m field %s on %s: %s" % (
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name,
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model._meta.object_name,
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e,
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))
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# Extract the options
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options = {}
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for name in DEFAULT_NAMES:
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# Ignore some special options
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if name in ["apps", "app_label"]:
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continue
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elif name in model._meta.original_attrs:
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if name == "unique_together":
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ut = model._meta.original_attrs["unique_together"]
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options[name] = set(normalize_together(ut))
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elif name == "index_together":
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it = model._meta.original_attrs["index_together"]
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options[name] = set(normalize_together(it))
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elif name == "indexes":
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indexes = [idx.clone() for idx in model._meta.indexes]
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for index in indexes:
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if not index.name:
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index.set_name_with_model(model)
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options['indexes'] = indexes
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elif name == 'constraints':
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options['constraints'] = [con.clone() for con in model._meta.constraints]
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else:
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options[name] = model._meta.original_attrs[name]
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# If we're ignoring relationships, remove all field-listing model
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# options (that option basically just means "make a stub model")
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if exclude_rels:
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for key in ["unique_together", "index_together", "order_with_respect_to"]:
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if key in options:
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del options[key]
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# Private fields are ignored, so remove options that refer to them.
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elif options.get('order_with_respect_to') in {field.name for field in model._meta.private_fields}:
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del options['order_with_respect_to']
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def flatten_bases(model):
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bases = []
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for base in model.__bases__:
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if hasattr(base, "_meta") and base._meta.abstract:
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bases.extend(flatten_bases(base))
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else:
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bases.append(base)
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return bases
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# We can't rely on __mro__ directly because we only want to flatten
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# abstract models and not the whole tree. However by recursing on
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# __bases__ we may end up with duplicates and ordering issues, we
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# therefore discard any duplicates and reorder the bases according
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# to their index in the MRO.
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flattened_bases = sorted(set(flatten_bases(model)), key=lambda x: model.__mro__.index(x))
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# Make our record
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|
bases = tuple(
|
|
(
|
|
base._meta.label_lower
|
|
if hasattr(base, "_meta") else
|
|
base
|
|
)
|
|
for base in flattened_bases
|
|
)
|
|
# Ensure at least one base inherits from models.Model
|
|
if not any((isinstance(base, str) or issubclass(base, models.Model)) for base in bases):
|
|
bases = (models.Model,)
|
|
|
|
managers = []
|
|
manager_names = set()
|
|
default_manager_shim = None
|
|
for manager in model._meta.managers:
|
|
if manager.name in manager_names:
|
|
# Skip overridden managers.
|
|
continue
|
|
elif manager.use_in_migrations:
|
|
# Copy managers usable in migrations.
|
|
new_manager = copy.copy(manager)
|
|
new_manager._set_creation_counter()
|
|
elif manager is model._base_manager or manager is model._default_manager:
|
|
# Shim custom managers used as default and base managers.
|
|
new_manager = models.Manager()
|
|
new_manager.model = manager.model
|
|
new_manager.name = manager.name
|
|
if manager is model._default_manager:
|
|
default_manager_shim = new_manager
|
|
else:
|
|
continue
|
|
manager_names.add(manager.name)
|
|
managers.append((manager.name, new_manager))
|
|
|
|
# Ignore a shimmed default manager called objects if it's the only one.
|
|
if managers == [('objects', default_manager_shim)]:
|
|
managers = []
|
|
|
|
# Construct the new ModelState
|
|
return cls(
|
|
model._meta.app_label,
|
|
model._meta.object_name,
|
|
fields,
|
|
options,
|
|
bases,
|
|
managers,
|
|
)
|
|
|
|
def construct_managers(self):
|
|
"""Deep-clone the managers using deconstruction."""
|
|
# Sort all managers by their creation counter
|
|
sorted_managers = sorted(self.managers, key=lambda v: v[1].creation_counter)
|
|
for mgr_name, manager in sorted_managers:
|
|
as_manager, manager_path, qs_path, args, kwargs = manager.deconstruct()
|
|
if as_manager:
|
|
qs_class = import_string(qs_path)
|
|
yield mgr_name, qs_class.as_manager()
|
|
else:
|
|
manager_class = import_string(manager_path)
|
|
yield mgr_name, manager_class(*args, **kwargs)
|
|
|
|
def clone(self):
|
|
"""Return an exact copy of this ModelState."""
|
|
return self.__class__(
|
|
app_label=self.app_label,
|
|
name=self.name,
|
|
fields=dict(self.fields),
|
|
# Since options are shallow-copied here, operations such as
|
|
# AddIndex must replace their option (e.g 'indexes') rather
|
|
# than mutating it.
|
|
options=dict(self.options),
|
|
bases=self.bases,
|
|
managers=list(self.managers),
|
|
)
|
|
|
|
def render(self, apps):
|
|
"""Create a Model object from our current state into the given apps."""
|
|
# First, make a Meta object
|
|
meta_contents = {'app_label': self.app_label, 'apps': apps, **self.options}
|
|
meta = type("Meta", (), meta_contents)
|
|
# Then, work out our bases
|
|
try:
|
|
bases = tuple(
|
|
(apps.get_model(base) if isinstance(base, str) else base)
|
|
for base in self.bases
|
|
)
|
|
except LookupError:
|
|
raise InvalidBasesError("Cannot resolve one or more bases from %r" % (self.bases,))
|
|
# Clone fields for the body, add other bits.
|
|
body = {name: field.clone() for name, field in self.fields.items()}
|
|
body['Meta'] = meta
|
|
body['__module__'] = "__fake__"
|
|
|
|
# Restore managers
|
|
body.update(self.construct_managers())
|
|
# Then, make a Model object (apps.register_model is called in __new__)
|
|
return type(self.name, bases, body)
|
|
|
|
def get_index_by_name(self, name):
|
|
for index in self.options['indexes']:
|
|
if index.name == name:
|
|
return index
|
|
raise ValueError("No index named %s on model %s" % (name, self.name))
|
|
|
|
def get_constraint_by_name(self, name):
|
|
for constraint in self.options['constraints']:
|
|
if constraint.name == name:
|
|
return constraint
|
|
raise ValueError('No constraint named %s on model %s' % (name, self.name))
|
|
|
|
def __repr__(self):
|
|
return "<%s: '%s.%s'>" % (self.__class__.__name__, self.app_label, self.name)
|
|
|
|
def __eq__(self, other):
|
|
return (
|
|
(self.app_label == other.app_label) and
|
|
(self.name == other.name) and
|
|
(len(self.fields) == len(other.fields)) and
|
|
all(
|
|
k1 == k2 and f1.deconstruct()[1:] == f2.deconstruct()[1:]
|
|
for (k1, f1), (k2, f2) in zip(
|
|
sorted(self.fields.items()),
|
|
sorted(other.fields.items()),
|
|
)
|
|
) and
|
|
(self.options == other.options) and
|
|
(self.bases == other.bases) and
|
|
(self.managers == other.managers)
|
|
)
|