mysteriendrama/lib/python3.11/site-packages/django/db/models/utils.py

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2023-07-22 12:04:19 +02:00
import functools
from collections import namedtuple
def make_model_tuple(model):
"""
Take a model or a string of the form "app_label.ModelName" and return a
corresponding ("app_label", "modelname") tuple. If a tuple is passed in,
assume it's a valid model tuple already and return it unchanged.
"""
try:
if isinstance(model, tuple):
model_tuple = model
elif isinstance(model, str):
app_label, model_name = model.split(".")
model_tuple = app_label, model_name.lower()
else:
model_tuple = model._meta.app_label, model._meta.model_name
assert len(model_tuple) == 2
return model_tuple
except (ValueError, AssertionError):
raise ValueError(
"Invalid model reference '%s'. String model references "
"must be of the form 'app_label.ModelName'." % model
)
def resolve_callables(mapping):
"""
Generate key/value pairs for the given mapping where the values are
evaluated if they're callable.
"""
for k, v in mapping.items():
yield k, v() if callable(v) else v
def unpickle_named_row(names, values):
return create_namedtuple_class(*names)(*values)
@functools.lru_cache
def create_namedtuple_class(*names):
# Cache type() with @lru_cache since it's too slow to be called for every
# QuerySet evaluation.
def __reduce__(self):
return unpickle_named_row, (names, tuple(self))
return type(
"Row",
(namedtuple("Row", names),),
{"__reduce__": __reduce__, "__slots__": ()},
)
class AltersData:
"""
Make subclasses preserve the alters_data attribute on overridden methods.
"""
def __init_subclass__(cls, **kwargs):
for fn_name, fn in vars(cls).items():
if callable(fn) and not hasattr(fn, "alters_data"):
for base in cls.__bases__:
if base_fn := getattr(base, fn_name, None):
if hasattr(base_fn, "alters_data"):
fn.alters_data = base_fn.alters_data
break
super().__init_subclass__(**kwargs)