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- from importlib import import_module
- from django.utils.version import get_docs_version
- def deconstructible(*args, path=None):
- """
- Class decorator that allows the decorated class to be serialized
- by the migrations subsystem.
- The `path` kwarg specifies the import path.
- """
- def decorator(klass):
- def __new__(cls, *args, **kwargs):
-
- obj = super(klass, cls).__new__(cls)
- obj._constructor_args = (args, kwargs)
- return obj
- def deconstruct(obj):
- """
- Return a 3-tuple of class import path, positional arguments,
- and keyword arguments.
- """
-
- if path and type(obj) is klass:
- module_name, _, name = path.rpartition(".")
- else:
- module_name = obj.__module__
- name = obj.__class__.__name__
-
- module = import_module(module_name)
- if not hasattr(module, name):
- raise ValueError(
- "Could not find object %s in %s.\n"
- "Please note that you cannot serialize things like inner "
- "classes. Please move the object into the main module "
- "body to use migrations.\n"
- "For more information, see "
- "https://docs.djangoproject.com/en/%s/topics/migrations/"
- "#serializing-values" % (name, module_name, get_docs_version())
- )
- return (
- (
- path
- if path and type(obj) is klass
- else f"{obj.__class__.__module__}.{name}"
- ),
- obj._constructor_args[0],
- obj._constructor_args[1],
- )
- klass.__new__ = staticmethod(__new__)
- klass.deconstruct = deconstruct
- return klass
- if not args:
- return decorator
- return decorator(*args)
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