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- import copy
- from collections import defaultdict
- from contextlib import contextmanager
- from functools import partial
-
- from django.apps import AppConfig
- from django.apps.registry import Apps
- from django.apps.registry import apps as global_apps
- from django.conf import settings
- from django.core.exceptions import FieldDoesNotExist
- from django.db import models
- from django.db.migrations.utils import field_is_referenced, get_references
- from django.db.models import NOT_PROVIDED
- from django.db.models.fields.related import RECURSIVE_RELATIONSHIP_CONSTANT
- from django.db.models.options import DEFAULT_NAMES, normalize_together
- from django.db.models.utils import make_model_tuple
- from django.utils.functional import cached_property
- from django.utils.module_loading import import_string
- from django.utils.version import get_docs_version
-
- from .exceptions import InvalidBasesError
- from .utils import resolve_relation
-
-
- def _get_app_label_and_model_name(model, app_label=""):
- if isinstance(model, str):
- split = model.split(".", 1)
- return tuple(split) if len(split) == 2 else (app_label, split[0])
- else:
- return model._meta.app_label, model._meta.model_name
-
-
- def _get_related_models(m):
- """Return all models that have a direct relationship to the given model."""
- related_models = [
- subclass
- for subclass in m.__subclasses__()
- if issubclass(subclass, models.Model)
- ]
- related_fields_models = set()
- for f in m._meta.get_fields(include_parents=True, include_hidden=True):
- if (
- f.is_relation
- and f.related_model is not None
- and not isinstance(f.related_model, str)
- ):
- related_fields_models.add(f.model)
- related_models.append(f.related_model)
- # Reverse accessors of foreign keys to proxy models are attached to their
- # concrete proxied model.
- opts = m._meta
- if opts.proxy and m in related_fields_models:
- related_models.append(opts.concrete_model)
- return related_models
-
-
- def get_related_models_tuples(model):
- """
- Return a list of typical (app_label, model_name) tuples for all related
- models for the given model.
- """
- return {
- (rel_mod._meta.app_label, rel_mod._meta.model_name)
- for rel_mod in _get_related_models(model)
- }
-
-
- def get_related_models_recursive(model):
- """
- Return all models that have a direct or indirect relationship
- to the given model.
-
- Relationships are either defined by explicit relational fields, like
- ForeignKey, ManyToManyField or OneToOneField, or by inheriting from another
- model (a superclass is related to its subclasses, but not vice versa). Note,
- however, that a model inheriting from a concrete model is also related to
- its superclass through the implicit *_ptr OneToOneField on the subclass.
- """
- seen = set()
- queue = _get_related_models(model)
- for rel_mod in queue:
- rel_app_label, rel_model_name = (
- rel_mod._meta.app_label,
- rel_mod._meta.model_name,
- )
- if (rel_app_label, rel_model_name) in seen:
- continue
- seen.add((rel_app_label, rel_model_name))
- queue.extend(_get_related_models(rel_mod))
- return seen - {(model._meta.app_label, model._meta.model_name)}
-
-
- class ProjectState:
- """
- Represent the entire project's overall state. This is the item that is
- passed around - do it here rather than at the app level so that cross-app
- FKs/etc. resolve properly.
- """
-
- def __init__(self, models=None, real_apps=None):
- self.models = models or {}
- # Apps to include from main registry, usually unmigrated ones
- if real_apps is None:
- real_apps = set()
- else:
- assert isinstance(real_apps, set)
- self.real_apps = real_apps
- self.is_delayed = False
- # {remote_model_key: {model_key: {field_name: field}}}
- self._relations = None
-
- @property
- def relations(self):
- if self._relations is None:
- self.resolve_fields_and_relations()
- return self._relations
-
- def add_model(self, model_state):
- model_key = model_state.app_label, model_state.name_lower
- self.models[model_key] = model_state
- if self._relations is not None:
- self.resolve_model_relations(model_key)
- if "apps" in self.__dict__: # hasattr would cache the property
- self.reload_model(*model_key)
-
- def remove_model(self, app_label, model_name):
- model_key = app_label, model_name
- del self.models[model_key]
- if self._relations is not None:
- self._relations.pop(model_key, None)
- # Call list() since _relations can change size during iteration.
- for related_model_key, model_relations in list(self._relations.items()):
- model_relations.pop(model_key, None)
- if not model_relations:
- del self._relations[related_model_key]
- if "apps" in self.__dict__: # hasattr would cache the property
- self.apps.unregister_model(*model_key)
- # Need to do this explicitly since unregister_model() doesn't clear
- # the cache automatically (#24513)
- self.apps.clear_cache()
-
- def rename_model(self, app_label, old_name, new_name):
- # Add a new model.
- old_name_lower = old_name.lower()
- new_name_lower = new_name.lower()
- renamed_model = self.models[app_label, old_name_lower].clone()
- renamed_model.name = new_name
- self.models[app_label, new_name_lower] = renamed_model
- # Repoint all fields pointing to the old model to the new one.
- old_model_tuple = (app_label, old_name_lower)
- new_remote_model = f"{app_label}.{new_name}"
- to_reload = set()
- for model_state, name, field, reference in get_references(
- self, old_model_tuple
- ):
- changed_field = None
- if reference.to:
- changed_field = field.clone()
- changed_field.remote_field.model = new_remote_model
- if reference.through:
- if changed_field is None:
- changed_field = field.clone()
- changed_field.remote_field.through = new_remote_model
- if changed_field:
- model_state.fields[name] = changed_field
- to_reload.add((model_state.app_label, model_state.name_lower))
- if self._relations is not None:
- old_name_key = app_label, old_name_lower
- new_name_key = app_label, new_name_lower
- if old_name_key in self._relations:
- self._relations[new_name_key] = self._relations.pop(old_name_key)
- for model_relations in self._relations.values():
- if old_name_key in model_relations:
- model_relations[new_name_key] = model_relations.pop(old_name_key)
- # Reload models related to old model before removing the old model.
- self.reload_models(to_reload, delay=True)
- # Remove the old model.
- self.remove_model(app_label, old_name_lower)
- self.reload_model(app_label, new_name_lower, delay=True)
-
- def alter_model_options(self, app_label, model_name, options, option_keys=None):
- model_state = self.models[app_label, model_name]
- model_state.options = {**model_state.options, **options}
- if option_keys:
- for key in option_keys:
- if key not in options:
- model_state.options.pop(key, False)
- self.reload_model(app_label, model_name, delay=True)
-
- def remove_model_options(self, app_label, model_name, option_name, value_to_remove):
- model_state = self.models[app_label, model_name]
- if objs := model_state.options.get(option_name):
- model_state.options[option_name] = [
- obj for obj in objs if tuple(obj) != tuple(value_to_remove)
- ]
- self.reload_model(app_label, model_name, delay=True)
-
- def alter_model_managers(self, app_label, model_name, managers):
- model_state = self.models[app_label, model_name]
- model_state.managers = list(managers)
- self.reload_model(app_label, model_name, delay=True)
-
- def _append_option(self, app_label, model_name, option_name, obj):
- model_state = self.models[app_label, model_name]
- model_state.options[option_name] = [*model_state.options[option_name], obj]
- self.reload_model(app_label, model_name, delay=True)
-
- def _remove_option(self, app_label, model_name, option_name, obj_name):
- model_state = self.models[app_label, model_name]
- objs = model_state.options[option_name]
- model_state.options[option_name] = [obj for obj in objs if obj.name != obj_name]
- self.reload_model(app_label, model_name, delay=True)
-
- def add_index(self, app_label, model_name, index):
- self._append_option(app_label, model_name, "indexes", index)
-
- def remove_index(self, app_label, model_name, index_name):
- self._remove_option(app_label, model_name, "indexes", index_name)
-
- def rename_index(self, app_label, model_name, old_index_name, new_index_name):
- model_state = self.models[app_label, model_name]
- objs = model_state.options["indexes"]
-
- new_indexes = []
- for obj in objs:
- if obj.name == old_index_name:
- obj = obj.clone()
- obj.name = new_index_name
- new_indexes.append(obj)
-
- model_state.options["indexes"] = new_indexes
- self.reload_model(app_label, model_name, delay=True)
-
- def add_constraint(self, app_label, model_name, constraint):
- self._append_option(app_label, model_name, "constraints", constraint)
-
- def remove_constraint(self, app_label, model_name, constraint_name):
- self._remove_option(app_label, model_name, "constraints", constraint_name)
-
- def add_field(self, app_label, model_name, name, field, preserve_default):
- # If preserve default is off, don't use the default for future state.
- if not preserve_default:
- field = field.clone()
- field.default = NOT_PROVIDED
- else:
- field = field
- model_key = app_label, model_name
- self.models[model_key].fields[name] = field
- if self._relations is not None:
- self.resolve_model_field_relations(model_key, name, field)
- # Delay rendering of relationships if it's not a relational field.
- delay = not field.is_relation
- self.reload_model(*model_key, delay=delay)
-
- def remove_field(self, app_label, model_name, name):
- model_key = app_label, model_name
- model_state = self.models[model_key]
- old_field = model_state.fields.pop(name)
- if self._relations is not None:
- self.resolve_model_field_relations(model_key, name, old_field)
- # Delay rendering of relationships if it's not a relational field.
- delay = not old_field.is_relation
- self.reload_model(*model_key, delay=delay)
-
- def alter_field(self, app_label, model_name, name, field, preserve_default):
- if not preserve_default:
- field = field.clone()
- field.default = NOT_PROVIDED
- else:
- field = field
- model_key = app_label, model_name
- fields = self.models[model_key].fields
- if self._relations is not None:
- old_field = fields.pop(name)
- if old_field.is_relation:
- self.resolve_model_field_relations(model_key, name, old_field)
- fields[name] = field
- if field.is_relation:
- self.resolve_model_field_relations(model_key, name, field)
- else:
- fields[name] = field
- # TODO: investigate if old relational fields must be reloaded or if
- # it's sufficient if the new field is (#27737).
- # Delay rendering of relationships if it's not a relational field and
- # not referenced by a foreign key.
- delay = not field.is_relation and not field_is_referenced(
- self, model_key, (name, field)
- )
- self.reload_model(*model_key, delay=delay)
-
- def rename_field(self, app_label, model_name, old_name, new_name):
- model_key = app_label, model_name
- model_state = self.models[model_key]
- # Rename the field.
- fields = model_state.fields
- try:
- found = fields.pop(old_name)
- except KeyError:
- raise FieldDoesNotExist(
- f"{app_label}.{model_name} has no field named '{old_name}'"
- )
- fields[new_name] = found
- for field in fields.values():
- # Fix from_fields to refer to the new field.
- from_fields = getattr(field, "from_fields", None)
- if from_fields:
- field.from_fields = tuple(
- [
- new_name if from_field_name == old_name else from_field_name
- for from_field_name in from_fields
- ]
- )
- # Fix index/unique_together to refer to the new field.
- options = model_state.options
- for option in ("index_together", "unique_together"):
- if option in options:
- options[option] = [
- [new_name if n == old_name else n for n in together]
- for together in options[option]
- ]
- # Fix to_fields to refer to the new field.
- delay = True
- references = get_references(self, model_key, (old_name, found))
- for *_, field, reference in references:
- delay = False
- if reference.to:
- remote_field, to_fields = reference.to
- if getattr(remote_field, "field_name", None) == old_name:
- remote_field.field_name = new_name
- if to_fields:
- field.to_fields = tuple(
- [
- new_name if to_field_name == old_name else to_field_name
- for to_field_name in to_fields
- ]
- )
- if self._relations is not None:
- old_name_lower = old_name.lower()
- new_name_lower = new_name.lower()
- for to_model in self._relations.values():
- if old_name_lower in to_model[model_key]:
- field = to_model[model_key].pop(old_name_lower)
- field.name = new_name_lower
- to_model[model_key][new_name_lower] = field
- self.reload_model(*model_key, delay=delay)
-
- def _find_reload_model(self, app_label, model_name, delay=False):
- if delay:
- self.is_delayed = True
-
- related_models = set()
-
- try:
- old_model = self.apps.get_model(app_label, model_name)
- except LookupError:
- pass
- else:
- # Get all relations to and from the old model before reloading,
- # as _meta.apps may change
- if delay:
- related_models = get_related_models_tuples(old_model)
- else:
- related_models = get_related_models_recursive(old_model)
-
- # Get all outgoing references from the model to be rendered
- model_state = self.models[(app_label, model_name)]
- # Directly related models are the models pointed to by ForeignKeys,
- # OneToOneFields, and ManyToManyFields.
- direct_related_models = set()
- for field in model_state.fields.values():
- if field.is_relation:
- if field.remote_field.model == RECURSIVE_RELATIONSHIP_CONSTANT:
- continue
- rel_app_label, rel_model_name = _get_app_label_and_model_name(
- field.related_model, app_label
- )
- direct_related_models.add((rel_app_label, rel_model_name.lower()))
-
- # For all direct related models recursively get all related models.
- related_models.update(direct_related_models)
- for rel_app_label, rel_model_name in direct_related_models:
- try:
- rel_model = self.apps.get_model(rel_app_label, rel_model_name)
- except LookupError:
- pass
- else:
- if delay:
- related_models.update(get_related_models_tuples(rel_model))
- else:
- related_models.update(get_related_models_recursive(rel_model))
-
- # Include the model itself
- related_models.add((app_label, model_name))
-
- return related_models
-
- def reload_model(self, app_label, model_name, delay=False):
- if "apps" in self.__dict__: # hasattr would cache the property
- related_models = self._find_reload_model(app_label, model_name, delay)
- self._reload(related_models)
-
- def reload_models(self, models, delay=True):
- if "apps" in self.__dict__: # hasattr would cache the property
- related_models = set()
- for app_label, model_name in models:
- related_models.update(
- self._find_reload_model(app_label, model_name, delay)
- )
- self._reload(related_models)
-
- def _reload(self, related_models):
- # Unregister all related models
- with self.apps.bulk_update():
- for rel_app_label, rel_model_name in related_models:
- self.apps.unregister_model(rel_app_label, rel_model_name)
-
- states_to_be_rendered = []
- # Gather all models states of those models that will be rerendered.
- # This includes:
- # 1. All related models of unmigrated apps
- for model_state in self.apps.real_models:
- if (model_state.app_label, model_state.name_lower) in related_models:
- states_to_be_rendered.append(model_state)
-
- # 2. All related models of migrated apps
- for rel_app_label, rel_model_name in related_models:
- try:
- model_state = self.models[rel_app_label, rel_model_name]
- except KeyError:
- pass
- else:
- states_to_be_rendered.append(model_state)
-
- # Render all models
- self.apps.render_multiple(states_to_be_rendered)
-
- def update_model_field_relation(
- self,
- model,
- model_key,
- field_name,
- field,
- concretes,
- ):
- remote_model_key = resolve_relation(model, *model_key)
- if remote_model_key[0] not in self.real_apps and remote_model_key in concretes:
- remote_model_key = concretes[remote_model_key]
- relations_to_remote_model = self._relations[remote_model_key]
- if field_name in self.models[model_key].fields:
- # The assert holds because it's a new relation, or an altered
- # relation, in which case references have been removed by
- # alter_field().
- assert field_name not in relations_to_remote_model[model_key]
- relations_to_remote_model[model_key][field_name] = field
- else:
- del relations_to_remote_model[model_key][field_name]
- if not relations_to_remote_model[model_key]:
- del relations_to_remote_model[model_key]
-
- def resolve_model_field_relations(
- self,
- model_key,
- field_name,
- field,
- concretes=None,
- ):
- remote_field = field.remote_field
- if not remote_field:
- return
- if concretes is None:
- concretes, _ = self._get_concrete_models_mapping_and_proxy_models()
-
- self.update_model_field_relation(
- remote_field.model,
- model_key,
- field_name,
- field,
- concretes,
- )
-
- through = getattr(remote_field, "through", None)
- if not through:
- return
- self.update_model_field_relation(
- through, model_key, field_name, field, concretes
- )
-
- def resolve_model_relations(self, model_key, concretes=None):
- if concretes is None:
- concretes, _ = self._get_concrete_models_mapping_and_proxy_models()
-
- model_state = self.models[model_key]
- for field_name, field in model_state.fields.items():
- self.resolve_model_field_relations(model_key, field_name, field, concretes)
-
- def resolve_fields_and_relations(self):
- # Resolve fields.
- for model_state in self.models.values():
- for field_name, field in model_state.fields.items():
- field.name = field_name
- # Resolve relations.
- # {remote_model_key: {model_key: {field_name: field}}}
- self._relations = defaultdict(partial(defaultdict, dict))
- concretes, proxies = self._get_concrete_models_mapping_and_proxy_models()
-
- for model_key in concretes:
- self.resolve_model_relations(model_key, concretes)
-
- for model_key in proxies:
- self._relations[model_key] = self._relations[concretes[model_key]]
-
- def get_concrete_model_key(self, model):
- (
- concrete_models_mapping,
- _,
- ) = self._get_concrete_models_mapping_and_proxy_models()
- model_key = make_model_tuple(model)
- return concrete_models_mapping[model_key]
-
- def _get_concrete_models_mapping_and_proxy_models(self):
- concrete_models_mapping = {}
- proxy_models = {}
- # Split models to proxy and concrete models.
- for model_key, model_state in self.models.items():
- if model_state.options.get("proxy"):
- proxy_models[model_key] = model_state
- # Find a concrete model for the proxy.
- concrete_models_mapping[
- model_key
- ] = self._find_concrete_model_from_proxy(
- proxy_models,
- model_state,
- )
- else:
- concrete_models_mapping[model_key] = model_key
- return concrete_models_mapping, proxy_models
-
- def _find_concrete_model_from_proxy(self, proxy_models, model_state):
- for base in model_state.bases:
- if not (isinstance(base, str) or issubclass(base, models.Model)):
- continue
- base_key = make_model_tuple(base)
- base_state = proxy_models.get(base_key)
- if not base_state:
- # Concrete model found, stop looking at bases.
- return base_key
- return self._find_concrete_model_from_proxy(proxy_models, base_state)
-
- def clone(self):
- """Return an exact copy of this ProjectState."""
- new_state = ProjectState(
- models={k: v.clone() for k, v in self.models.items()},
- real_apps=self.real_apps,
- )
- if "apps" in self.__dict__:
- new_state.apps = self.apps.clone()
- new_state.is_delayed = self.is_delayed
- return new_state
-
- def clear_delayed_apps_cache(self):
- if self.is_delayed and "apps" in self.__dict__:
- del self.__dict__["apps"]
-
- @cached_property
- def apps(self):
- return StateApps(self.real_apps, self.models)
-
- @classmethod
- def from_apps(cls, apps):
- """Take an Apps and return a ProjectState matching it."""
- app_models = {}
- for model in apps.get_models(include_swapped=True):
- model_state = ModelState.from_model(model)
- app_models[(model_state.app_label, model_state.name_lower)] = model_state
- return cls(app_models)
-
- def __eq__(self, other):
- return self.models == other.models and self.real_apps == other.real_apps
-
-
- class AppConfigStub(AppConfig):
- """Stub of an AppConfig. Only provides a label and a dict of models."""
-
- def __init__(self, label):
- self.apps = None
- self.models = {}
- # App-label and app-name are not the same thing, so technically passing
- # in the label here is wrong. In practice, migrations don't care about
- # the app name, but we need something unique, and the label works fine.
- self.label = label
- self.name = label
-
- def import_models(self):
- self.models = self.apps.all_models[self.label]
-
-
- class StateApps(Apps):
- """
- Subclass of the global Apps registry class to better handle dynamic model
- additions and removals.
- """
-
- def __init__(self, real_apps, models, ignore_swappable=False):
- # Any apps in self.real_apps should have all their models included
- # in the render. We don't use the original model instances as there
- # are some variables that refer to the Apps object.
- # FKs/M2Ms from real apps are also not included as they just
- # mess things up with partial states (due to lack of dependencies)
- self.real_models = []
- for app_label in real_apps:
- app = global_apps.get_app_config(app_label)
- for model in app.get_models():
- self.real_models.append(ModelState.from_model(model, exclude_rels=True))
- # Populate the app registry with a stub for each application.
- app_labels = {model_state.app_label for model_state in models.values()}
- app_configs = [
- AppConfigStub(label) for label in sorted([*real_apps, *app_labels])
- ]
- super().__init__(app_configs)
-
- # These locks get in the way of copying as implemented in clone(),
- # which is called whenever Django duplicates a StateApps before
- # updating it.
- self._lock = None
- self.ready_event = None
-
- self.render_multiple([*models.values(), *self.real_models])
-
- # There shouldn't be any operations pending at this point.
- from django.core.checks.model_checks import _check_lazy_references
-
- ignore = (
- {make_model_tuple(settings.AUTH_USER_MODEL)} if ignore_swappable else set()
- )
- errors = _check_lazy_references(self, ignore=ignore)
- if errors:
- raise ValueError("\n".join(error.msg for error in errors))
-
- @contextmanager
- def bulk_update(self):
- # Avoid clearing each model's cache for each change. Instead, clear
- # all caches when we're finished updating the model instances.
- ready = self.ready
- self.ready = False
- try:
- yield
- finally:
- self.ready = ready
- self.clear_cache()
-
- def render_multiple(self, model_states):
- # We keep trying to render the models in a loop, ignoring invalid
- # base errors, until the size of the unrendered models doesn't
- # decrease by at least one, meaning there's a base dependency loop/
- # missing base.
- if not model_states:
- return
- # Prevent that all model caches are expired for each render.
- with self.bulk_update():
- unrendered_models = model_states
- while unrendered_models:
- new_unrendered_models = []
- for model in unrendered_models:
- try:
- model.render(self)
- except InvalidBasesError:
- new_unrendered_models.append(model)
- if len(new_unrendered_models) == len(unrendered_models):
- raise InvalidBasesError(
- "Cannot resolve bases for %r\nThis can happen if you are "
- "inheriting models from an app with migrations (e.g. "
- "contrib.auth)\n in an app with no migrations; see "
- "https://docs.djangoproject.com/en/%s/topics/migrations/"
- "#dependencies for more"
- % (new_unrendered_models, get_docs_version())
- )
- unrendered_models = new_unrendered_models
-
- def clone(self):
- """Return a clone of this registry."""
- clone = StateApps([], {})
- clone.all_models = copy.deepcopy(self.all_models)
- clone.app_configs = copy.deepcopy(self.app_configs)
- # Set the pointer to the correct app registry.
- for app_config in clone.app_configs.values():
- app_config.apps = clone
- # No need to actually clone them, they'll never change
- clone.real_models = self.real_models
- return clone
-
- def register_model(self, app_label, model):
- self.all_models[app_label][model._meta.model_name] = model
- if app_label not in self.app_configs:
- self.app_configs[app_label] = AppConfigStub(app_label)
- self.app_configs[app_label].apps = self
- self.app_configs[app_label].models[model._meta.model_name] = model
- self.do_pending_operations(model)
- self.clear_cache()
-
- def unregister_model(self, app_label, model_name):
- try:
- del self.all_models[app_label][model_name]
- del self.app_configs[app_label].models[model_name]
- except KeyError:
- pass
-
-
- class ModelState:
- """
- Represent a Django Model. Don't use the actual Model class as it's not
- designed to have its options changed - instead, mutate this one and then
- render it into a Model as required.
-
- Note that while you are allowed to mutate .fields, you are not allowed
- to mutate the Field instances inside there themselves - you must instead
- assign new ones, as these are not detached during a clone.
- """
-
- def __init__(
- self, app_label, name, fields, options=None, bases=None, managers=None
- ):
- self.app_label = app_label
- self.name = name
- self.fields = dict(fields)
- self.options = options or {}
- self.options.setdefault("indexes", [])
- self.options.setdefault("constraints", [])
- self.bases = bases or (models.Model,)
- self.managers = managers or []
- for name, field in self.fields.items():
- # Sanity-check that fields are NOT already bound to a model.
- if hasattr(field, "model"):
- raise ValueError(
- 'ModelState.fields cannot be bound to a model - "%s" is.' % name
- )
- # Sanity-check that relation fields are NOT referring to a model class.
- if field.is_relation and hasattr(field.related_model, "_meta"):
- raise ValueError(
- 'ModelState.fields cannot refer to a model class - "%s.to" does. '
- "Use a string reference instead." % name
- )
- if field.many_to_many and hasattr(field.remote_field.through, "_meta"):
- raise ValueError(
- 'ModelState.fields cannot refer to a model class - "%s.through" '
- "does. Use a string reference instead." % name
- )
- # Sanity-check that indexes have their name set.
- for index in self.options["indexes"]:
- if not index.name:
- raise ValueError(
- "Indexes passed to ModelState require a name attribute. "
- "%r doesn't have one." % index
- )
-
- @cached_property
- def name_lower(self):
- return self.name.lower()
-
- def get_field(self, field_name):
- if field_name == "_order":
- field_name = self.options.get("order_with_respect_to", field_name)
- return self.fields[field_name]
-
- @classmethod
- def from_model(cls, model, exclude_rels=False):
- """Given a model, return a ModelState representing it."""
- # Deconstruct the fields
- fields = []
- for field in model._meta.local_fields:
- if getattr(field, "remote_field", None) and exclude_rels:
- continue
- if isinstance(field, models.OrderWrt):
- continue
- name = field.name
- try:
- fields.append((name, field.clone()))
- except TypeError as e:
- raise TypeError(
- "Couldn't reconstruct field %s on %s: %s"
- % (
- name,
- model._meta.label,
- e,
- )
- )
- if not exclude_rels:
- for field in model._meta.local_many_to_many:
- name = field.name
- try:
- fields.append((name, field.clone()))
- except TypeError as e:
- raise TypeError(
- "Couldn't reconstruct m2m field %s on %s: %s"
- % (
- name,
- model._meta.object_name,
- e,
- )
- )
- # Extract the options
- options = {}
- for name in DEFAULT_NAMES:
- # Ignore some special options
- if name in ["apps", "app_label"]:
- continue
- elif name in model._meta.original_attrs:
- if name == "unique_together":
- ut = model._meta.original_attrs["unique_together"]
- options[name] = set(normalize_together(ut))
- elif name == "index_together":
- it = model._meta.original_attrs["index_together"]
- options[name] = set(normalize_together(it))
- elif name == "indexes":
- indexes = [idx.clone() for idx in model._meta.indexes]
- for index in indexes:
- if not index.name:
- index.set_name_with_model(model)
- options["indexes"] = indexes
- elif name == "constraints":
- options["constraints"] = [
- con.clone() for con in model._meta.constraints
- ]
- else:
- options[name] = model._meta.original_attrs[name]
- # If we're ignoring relationships, remove all field-listing model
- # options (that option basically just means "make a stub model")
- if exclude_rels:
- for key in ["unique_together", "index_together", "order_with_respect_to"]:
- if key in options:
- del options[key]
- # Private fields are ignored, so remove options that refer to them.
- elif options.get("order_with_respect_to") in {
- field.name for field in model._meta.private_fields
- }:
- del options["order_with_respect_to"]
-
- def flatten_bases(model):
- bases = []
- for base in model.__bases__:
- if hasattr(base, "_meta") and base._meta.abstract:
- bases.extend(flatten_bases(base))
- else:
- bases.append(base)
- return bases
-
- # We can't rely on __mro__ directly because we only want to flatten
- # abstract models and not the whole tree. However by recursing on
- # __bases__ we may end up with duplicates and ordering issues, we
- # therefore discard any duplicates and reorder the bases according
- # to their index in the MRO.
- flattened_bases = sorted(
- set(flatten_bases(model)), key=lambda x: model.__mro__.index(x)
- )
-
- # Make our record
- 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)
- )
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