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)