285 lines
12 KiB
Python
285 lines
12 KiB
Python
from django.apps import AppConfig
|
|
from django.apps.registry import Apps, apps as global_apps
|
|
from django.db import models
|
|
from django.db.models.options import DEFAULT_NAMES, normalize_together
|
|
from django.db.models.fields.related import do_pending_lookups
|
|
from django.utils import six
|
|
from django.utils.module_loading import import_string
|
|
|
|
|
|
class InvalidBasesError(ValueError):
|
|
pass
|
|
|
|
|
|
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 {}
|
|
self.apps = None
|
|
# Apps to include from main registry, usually unmigrated ones
|
|
self.real_apps = real_apps or []
|
|
|
|
def add_model_state(self, model_state):
|
|
self.models[(model_state.app_label, model_state.name.lower())] = model_state
|
|
|
|
def clone(self):
|
|
"Returns an exact copy of this ProjectState"
|
|
return ProjectState(
|
|
models=dict((k, v.clone()) for k, v in self.models.items()),
|
|
real_apps=self.real_apps,
|
|
)
|
|
|
|
def render(self, include_real=None):
|
|
"Turns the project state into actual models in a new Apps"
|
|
if self.apps is None:
|
|
# 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.
|
|
real_models = []
|
|
for app_label in self.real_apps:
|
|
app = global_apps.get_app_config(app_label)
|
|
for model in app.get_models():
|
|
real_models.append(ModelState.from_model(model))
|
|
# Populate the app registry with a stub for each application.
|
|
app_labels = set(model_state.app_label for model_state in self.models.values())
|
|
self.apps = Apps([AppConfigStub(label) for label in sorted(self.real_apps + list(app_labels))])
|
|
# 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.
|
|
unrendered_models = list(self.models.values()) + real_models
|
|
while unrendered_models:
|
|
new_unrendered_models = []
|
|
for model in unrendered_models:
|
|
try:
|
|
model.render(self.apps)
|
|
except InvalidBasesError:
|
|
new_unrendered_models.append(model)
|
|
if len(new_unrendered_models) == len(unrendered_models):
|
|
raise InvalidBasesError("Cannot resolve bases for %r" % new_unrendered_models)
|
|
unrendered_models = new_unrendered_models
|
|
# make sure apps has no dangling references
|
|
if self.apps._pending_lookups:
|
|
# There's some lookups left. See if we can first resolve them
|
|
# ourselves - sometimes fields are added after class_prepared is sent
|
|
for lookup_model, operations in self.apps._pending_lookups.items():
|
|
try:
|
|
model = self.apps.get_model(lookup_model[0], lookup_model[1])
|
|
except LookupError:
|
|
# Raise an error with a best-effort helpful message
|
|
# (only for the first issue). Error message should look like:
|
|
# "ValueError: Lookup failed for model referenced by
|
|
# field migrations.Book.author: migrations.Author"
|
|
raise ValueError("Lookup failed for model referenced by field {field}: {model[0]}.{model[1]}".format(
|
|
field=operations[0][1],
|
|
model=lookup_model
|
|
))
|
|
else:
|
|
do_pending_lookups(model)
|
|
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():
|
|
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):
|
|
super(AppConfigStub, self).__init__(label, None)
|
|
|
|
def import_models(self, all_models):
|
|
self.models = all_models
|
|
|
|
|
|
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):
|
|
self.app_label = app_label
|
|
self.name = name
|
|
self.fields = fields
|
|
self.options = options or {}
|
|
self.bases = bases or (models.Model, )
|
|
# 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.")
|
|
|
|
@classmethod
|
|
def from_model(cls, model):
|
|
"""
|
|
Feed me a model, get a ModelState representing it out.
|
|
"""
|
|
# Deconstruct the fields
|
|
fields = []
|
|
for field in model._meta.local_fields:
|
|
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,
|
|
))
|
|
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
|
|
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))
|
|
else:
|
|
options[name] = model._meta.original_attrs[name]
|
|
|
|
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(
|
|
(
|
|
"%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,)
|
|
return cls(
|
|
model._meta.app_label,
|
|
model._meta.object_name,
|
|
fields,
|
|
options,
|
|
bases,
|
|
)
|
|
|
|
def clone(self):
|
|
"Returns an exact copy of this ModelState"
|
|
# We deep-clone the fields using deconstruction
|
|
fields = []
|
|
for name, field in self.fields:
|
|
_, path, args, kwargs = field.deconstruct()
|
|
field_class = import_string(path)
|
|
fields.append((name, field_class(*args, **kwargs)))
|
|
# Now make a copy
|
|
return self.__class__(
|
|
app_label=self.app_label,
|
|
name=self.name,
|
|
fields=fields,
|
|
options=dict(self.options),
|
|
bases=self.bases,
|
|
)
|
|
|
|
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)
|
|
if "unique_together" in meta_contents:
|
|
meta_contents["unique_together"] = list(meta_contents["unique_together"])
|
|
meta = type("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.fields)
|
|
body['Meta'] = meta
|
|
body['__module__'] = "__fake__"
|
|
# Then, make a Model object
|
|
return type(
|
|
str(self.name),
|
|
bases,
|
|
body,
|
|
)
|
|
|
|
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 __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)
|
|
)
|
|
|
|
def __ne__(self, other):
|
|
return not (self == other)
|