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