57 lines
1.8 KiB
Python
57 lines
1.8 KiB
Python
from django.core import checks
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NOT_PROVIDED = object()
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class FieldCacheMixin:
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"""Provide an API for working with the model's fields value cache."""
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def get_cache_name(self):
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raise NotImplementedError
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def get_cached_value(self, instance, default=NOT_PROVIDED):
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cache_name = self.get_cache_name()
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try:
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return instance._state.fields_cache[cache_name]
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except KeyError:
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if default is NOT_PROVIDED:
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raise
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return default
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def is_cached(self, instance):
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return self.get_cache_name() in instance._state.fields_cache
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def set_cached_value(self, instance, value):
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instance._state.fields_cache[self.get_cache_name()] = value
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def delete_cached_value(self, instance):
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del instance._state.fields_cache[self.get_cache_name()]
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class CheckFieldDefaultMixin:
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_default_hint = ('<valid default>', '<invalid default>')
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def _check_default(self):
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if self.has_default() and self.default is not None and not callable(self.default):
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return [
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checks.Warning(
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"%s default should be a callable instead of an instance "
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"so that it's not shared between all field instances." % (
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self.__class__.__name__,
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),
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hint=(
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'Use a callable instead, e.g., use `%s` instead of '
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'`%s`.' % self._default_hint
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),
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obj=self,
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id='fields.E010',
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)
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]
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else:
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return []
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def check(self, **kwargs):
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errors = super().check(**kwargs)
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errors.extend(self._check_default())
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return errors
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