django1/django/db/migrations/state.py

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from __future__ import unicode_literals
import copy
from collections import OrderedDict
from django.apps import AppConfig
from django.apps.registry import Apps, apps as global_apps
from django.conf import settings
from django.db import models
from django.db.models.fields.proxy import OrderWrt
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 import six
from django.utils.encoding import force_text, smart_text
from django.utils.functional import cached_property
from django.utils.module_loading import import_string
from django.utils.version import get_docs_version
class InvalidBasesError(ValueError):
pass
def _get_app_label_and_model_name(model, app_label=''):
if isinstance(model, six.string_types):
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_recursive(model):
"""
Returns 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.
"""
def _related_models(m):
return [
f.related_model for f in m._meta.get_fields(include_parents=True, include_hidden=True)
if f.is_relation and not isinstance(f.related_model, six.string_types)
] + [
subclass for subclass in m.__subclasses__()
if issubclass(subclass, models.Model)
]
seen = set()
queue = _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(_related_models(rel_mod))
return seen - {(model._meta.app_label, model._meta.model_name)}
class ProjectState(object):
"""
Represents the entire project's overall state.
This is the item that is passed around - we 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
self.real_apps = real_apps or []
def add_model(self, model_state):
app_label, model_name = model_state.app_label, model_state.name_lower
self.models[(app_label, model_name)] = model_state
if 'apps' in self.__dict__: # hasattr would cache the property
self.reload_model(app_label, model_name)
def remove_model(self, app_label, model_name):
del self.models[app_label, model_name]
if 'apps' in self.__dict__: # hasattr would cache the property
self.apps.unregister_model(app_label, model_name)
# Need to do this explicitly since unregister_model() doesn't clear
# the cache automatically (#24513)
self.apps.clear_cache()
def reload_model(self, app_label, model_name):
if 'apps' in self.__dict__: # hasattr would cache the property
try:
old_model = self.apps.get_model(app_label, model_name)
except LookupError:
related_models = set()
else:
# Get all relations to and from the old model before reloading,
# as _meta.apps may change
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)]
for name, field in model_state.fields:
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.remote_field.model, app_label)
related_models.add((rel_app_label, rel_model_name.lower()))
# Include the model itself
related_models.add((app_label, model_name))
# Unregister all related models
for rel_app_label, rel_model_name in related_models:
self.apps.unregister_model(rel_app_label, rel_model_name)
# Need to do it once all models are unregistered to avoid corrupting
# existing models' _meta
self.apps.clear_cache()
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)
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def clone(self):
"Returns 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()
return new_state
@cached_property
def apps(self):
return StateApps(self.real_apps, self.models)
@property
def concrete_apps(self):
self.apps = StateApps(self.real_apps, self.models, ignore_swappable=True)
return self.apps
@classmethod
def from_apps(cls, apps):
"Takes in an Apps and returns 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):
if set(self.models.keys()) != set(other.models.keys()):
return False
if set(self.real_apps) != set(other.real_apps):
return False
return all(model == other.models[key] for key, model in self.models.items())
def __ne__(self, other):
return not (self == other)
class AppConfigStub(AppConfig):
"""
Stubs a Django AppConfig. Only provides a label, and a dict of models.
"""
# Not used, but required by AppConfig.__init__
path = ''
def __init__(self, label):
self.label = label
# 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.
super(AppConfigStub, self).__init__(label, None)
def import_models(self, all_models):
self.models = all_models
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 + list(app_labels))]
super(StateApps, self).__init__(app_configs)
self.render_multiple(list(models.values()) + self.real_models)
# There shouldn't be any operations pending at this point.
pending_models = set(self._pending_operations)
if ignore_swappable:
pending_models -= {make_model_tuple(settings.AUTH_USER_MODEL)}
if pending_models:
msg = "Unhandled pending operations for models: %s"
labels = (".".join(model_key) for model_key in self._pending_operations)
raise ValueError(msg % ", ".join(labels))
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.
self.ready = False
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):
self.ready = True
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
self.ready = True
self.clear_cache()
def clone(self):
"""
Return a clone of this registry, mainly used by the migration framework.
"""
clone = StateApps([], {})
clone.all_models = copy.deepcopy(self.all_models)
clone.app_configs = copy.deepcopy(self.app_configs)
# 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].models = OrderedDict()
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(object):
"""
Represents a Django Model. We don't use the actual Model class
as it's not designed to have its options changed - instead, we
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 = force_text(name)
self.fields = fields
self.options = options or {}
self.bases = bases or (models.Model, )
self.managers = managers or []
# Sanity-check that fields is NOT a dict. It must be ordered.
if isinstance(self.fields, dict):
raise ValueError("ModelState.fields cannot be a dict - it must be a list of 2-tuples.")
# Sanity-check that fields are NOT already bound to a model.
for name, field in fields:
if hasattr(field, 'model'):
raise ValueError(
'ModelState.fields cannot be bound to a model - "%s" is.' % name
)
@cached_property
def name_lower(self):
return self.name.lower()
@classmethod
def from_model(cls, model, exclude_rels=False):
"""
Feed me a model, get a ModelState representing it out.
"""
# Deconstruct the fields
fields = []
for field in model._meta.local_fields:
if getattr(field, "remote_field", None) and exclude_rels:
continue
if isinstance(field, OrderWrt):
continue
name, path, args, kwargs = field.deconstruct()
field_class = import_string(path)
try:
fields.append((name, field_class(*args, **kwargs)))
except TypeError as e:
raise TypeError("Couldn't reconstruct field %s on %s.%s: %s" % (
name,
model._meta.app_label,
model._meta.object_name,
e,
))
if not exclude_rels:
for field in model._meta.local_many_to_many:
name, path, args, kwargs = field.deconstruct()
field_class = import_string(path)
try:
fields.append((name, field_class(*args, **kwargs)))
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
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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))
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else:
options[name] = model._meta.original_attrs[name]
# Force-convert all options to text_type (#23226)
options = cls.force_text_recursive(options)
# 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]
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.
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flattened_bases = sorted(set(flatten_bases(model)), key=lambda x: model.__mro__.index(x))
# Make our record
bases = tuple(
(
"%s.%s" % (base._meta.app_label, base._meta.model_name)
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, six.string_types) or issubclass(base, models.Model)) for base in bases):
bases = (models.Model,)
# Constructs all managers on the model
managers = {}
def reconstruct_manager(mgr):
as_manager, manager_path, qs_path, args, kwargs = mgr.deconstruct()
if as_manager:
qs_class = import_string(qs_path)
instance = qs_class.as_manager()
else:
manager_class = import_string(manager_path)
instance = manager_class(*args, **kwargs)
# We rely on the ordering of the creation_counter of the original
# instance
managers[mgr.name] = (mgr.creation_counter, instance)
if hasattr(model, "_default_manager"):
default_manager_name = model._default_manager.name
# Make sure the default manager is always the first
if model._default_manager.use_in_migrations:
reconstruct_manager(model._default_manager)
else:
# Force this manager to be the first and thus default
managers[default_manager_name] = (0, models.Manager())
# Sort all managers by their creation counter
for _, manager, _ in sorted(model._meta.managers):
if manager.name == "_base_manager" or not manager.use_in_migrations:
continue
reconstruct_manager(manager)
# Sort all managers by their creation counter but take only name and
# instance for further processing
managers = [
(name, instance) for name, (cc, instance) in
sorted(managers.items(), key=lambda v: v[1])
]
if managers == [(default_manager_name, models.Manager())]:
managers = []
else:
managers = []
# Construct the new ModelState
return cls(
model._meta.app_label,
model._meta.object_name,
fields,
options,
bases,
managers,
)
@classmethod
def force_text_recursive(cls, value):
if isinstance(value, six.string_types):
return smart_text(value)
elif isinstance(value, list):
return [cls.force_text_recursive(x) for x in value]
elif isinstance(value, tuple):
return tuple(cls.force_text_recursive(x) for x in value)
elif isinstance(value, set):
return set(cls.force_text_recursive(x) for x in value)
elif isinstance(value, dict):
return {
cls.force_text_recursive(k): cls.force_text_recursive(v)
for k, v in value.items()
}
return value
def construct_fields(self):
"Deep-clone the fields using deconstruction"
for name, field in self.fields:
_, path, args, kwargs = field.deconstruct()
field_class = import_string(path)
yield name, field_class(*args, **kwargs)
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):
"Returns an exact copy of this ModelState"
return self.__class__(
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app_label=self.app_label,
name=self.name,
fields=list(self.construct_fields()),
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options=dict(self.options),
bases=self.bases,
managers=list(self.construct_managers()),
)
def render(self, apps):
"Creates 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}
meta_contents.update(self.options)
meta = type(str("Meta"), tuple(), meta_contents)
# Then, work out our bases
try:
bases = tuple(
(apps.get_model(base) if isinstance(base, six.string_types) else base)
for base in self.bases
)
except LookupError:
raise InvalidBasesError("Cannot resolve one or more bases from %r" % (self.bases,))
# Turn fields into a dict for the body, add other bits
body = dict(self.construct_fields())
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(
str(self.name),
bases,
body,
)
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def get_field_by_name(self, name):
for fname, field in self.fields:
if fname == name:
return field
raise ValueError("No field called %s on model %s" % (name, self.name))
def __repr__(self):
return "<ModelState: '%s.%s'>" % (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(self.fields, other.fields)) and
(self.options == other.options) and
(self.bases == other.bases) and
(self.managers == other.managers)
)
def __ne__(self, other):
return not (self == other)