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86 lines
2.9 KiB
Python
86 lines
2.9 KiB
Python
"""
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We perform uniqueness checks explicitly on the serializer class, rather
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the using Django's `.full_clean()`.
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This gives us better separation of concerns, allows us to use single-step
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object creation, and makes it possible to switch between using the implicit
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`ModelSerializer` class and an equivelent explicit `Serializer` class.
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"""
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from django.core.exceptions import ValidationError
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from django.utils.translation import ugettext_lazy as _
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from rest_framework.utils.representation import smart_repr
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class UniqueValidator:
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"""
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Validator that corresponds to `unique=True` on a model field.
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"""
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# Validators with `requires_context` will have the field instance
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# passed to them when the field is instantiated.
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requires_context = True
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message = _('This field must be unique.')
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def __init__(self, queryset):
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self.queryset = queryset
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self.serializer_field = None
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def __call__(self, value):
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field = self.serializer_field
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# Determine the model field name that the serializer field corresponds to.
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field_name = field.source_attrs[0] if field.source_attrs else field.field_name
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# Determine the existing instance, if this is an update operation.
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instance = getattr(field.parent, 'instance', None)
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# Ensure uniqueness.
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filter_kwargs = {field_name: value}
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queryset = self.queryset.filter(**filter_kwargs)
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if instance:
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queryset = queryset.exclude(pk=instance.pk)
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if queryset.exists():
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raise ValidationError(self.message)
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def __repr__(self):
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return '<%s(queryset=%s)>' % (
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self.__class__.__name__,
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smart_repr(self.queryset)
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)
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class UniqueTogetherValidator:
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"""
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Validator that corresponds to `unique_together = (...)` on a model class.
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"""
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requires_context = True
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message = _('The fields {field_names} must make a unique set.')
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def __init__(self, queryset, fields):
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self.queryset = queryset
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self.fields = fields
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self.serializer_field = None
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def __call__(self, value):
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serializer = self.serializer_field
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# Determine the existing instance, if this is an update operation.
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instance = getattr(serializer, 'instance', None)
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# Ensure uniqueness.
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filter_kwargs = dict([
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(field_name, value[field_name]) for field_name in self.fields
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])
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queryset = self.queryset.filter(**filter_kwargs)
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if instance:
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queryset = queryset.exclude(pk=instance.pk)
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if queryset.exists():
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field_names = ', '.join(self.fields)
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raise ValidationError(self.message.format(field_names=field_names))
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def __repr__(self):
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return '<%s(queryset=%s, fields=%s)>' % (
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self.__class__.__name__,
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smart_repr(self.queryset),
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smart_repr(self.fields)
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)
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