281 lines
10 KiB
Python
281 lines
10 KiB
Python
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"""
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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 equivalent explicit `Serializer` class.
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"""
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from django.db import DataError
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from django.utils.translation import gettext_lazy as _
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from rest_framework.exceptions import ValidationError
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from rest_framework.utils.representation import smart_repr
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# Robust filter and exist implementations. Ensures that queryset.exists() for
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# an invalid value returns `False`, rather than raising an error.
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# Refs https://github.com/encode/django-rest-framework/issues/3381
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def qs_exists(queryset):
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try:
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return queryset.exists()
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except (TypeError, ValueError, DataError):
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return False
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def qs_filter(queryset, **kwargs):
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try:
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return queryset.filter(**kwargs)
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except (TypeError, ValueError, DataError):
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return queryset.none()
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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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Should be applied to an individual field on the serializer.
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"""
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message = _('This field must be unique.')
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requires_context = True
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def __init__(self, queryset, message=None, lookup='exact'):
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self.queryset = queryset
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self.message = message or self.message
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self.lookup = lookup
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def filter_queryset(self, value, queryset, field_name):
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"""
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Filter the queryset to all instances matching the given attribute.
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"""
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filter_kwargs = {'%s__%s' % (field_name, self.lookup): value}
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return qs_filter(queryset, **filter_kwargs)
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def exclude_current_instance(self, queryset, instance):
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"""
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If an instance is being updated, then do not include
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that instance itself as a uniqueness conflict.
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"""
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if instance is not None:
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return queryset.exclude(pk=instance.pk)
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return queryset
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def __call__(self, value, serializer_field):
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# Determine the underlying model field name. This may not be the
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# same as the serializer field name if `source=<>` is set.
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field_name = serializer_field.source_attrs[-1]
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# Determine the existing instance, if this is an update operation.
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instance = getattr(serializer_field.parent, 'instance', None)
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queryset = self.queryset
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queryset = self.filter_queryset(value, queryset, field_name)
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queryset = self.exclude_current_instance(queryset, instance)
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if qs_exists(queryset):
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raise ValidationError(self.message, code='unique')
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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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Should be applied to the serializer class, not to an individual field.
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"""
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message = _('The fields {field_names} must make a unique set.')
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missing_message = _('This field is required.')
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requires_context = True
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def __init__(self, queryset, fields, message=None):
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self.queryset = queryset
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self.fields = fields
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self.message = message or self.message
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def enforce_required_fields(self, attrs, serializer):
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"""
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The `UniqueTogetherValidator` always forces an implied 'required'
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state on the fields it applies to.
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"""
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if serializer.instance is not None:
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return
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missing_items = {
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field_name: self.missing_message
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for field_name in self.fields
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if serializer.fields[field_name].source not in attrs
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}
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if missing_items:
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raise ValidationError(missing_items, code='required')
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def filter_queryset(self, attrs, queryset, serializer):
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"""
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Filter the queryset to all instances matching the given attributes.
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"""
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# field names => field sources
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sources = [
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serializer.fields[field_name].source
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for field_name in self.fields
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]
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# If this is an update, then any unprovided field should
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# have it's value set based on the existing instance attribute.
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if serializer.instance is not None:
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for source in sources:
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if source not in attrs:
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attrs[source] = getattr(serializer.instance, source)
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# Determine the filter keyword arguments and filter the queryset.
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filter_kwargs = {
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source: attrs[source]
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for source in sources
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}
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return qs_filter(queryset, **filter_kwargs)
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def exclude_current_instance(self, attrs, queryset, instance):
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"""
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If an instance is being updated, then do not include
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that instance itself as a uniqueness conflict.
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"""
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if instance is not None:
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return queryset.exclude(pk=instance.pk)
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return queryset
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def __call__(self, attrs, serializer):
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self.enforce_required_fields(attrs, serializer)
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queryset = self.queryset
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queryset = self.filter_queryset(attrs, queryset, serializer)
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queryset = self.exclude_current_instance(attrs, queryset, serializer.instance)
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# Ignore validation if any field is None
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checked_values = [
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value for field, value in attrs.items() if field in self.fields
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]
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if None not in checked_values and qs_exists(queryset):
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field_names = ', '.join(self.fields)
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message = self.message.format(field_names=field_names)
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raise ValidationError(message, code='unique')
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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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class ProhibitSurrogateCharactersValidator:
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message = _('Surrogate characters are not allowed: U+{code_point:X}.')
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code = 'surrogate_characters_not_allowed'
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def __call__(self, value):
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for surrogate_character in (ch for ch in str(value)
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if 0xD800 <= ord(ch) <= 0xDFFF):
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message = self.message.format(code_point=ord(surrogate_character))
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raise ValidationError(message, code=self.code)
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class BaseUniqueForValidator:
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message = None
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missing_message = _('This field is required.')
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requires_context = True
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def __init__(self, queryset, field, date_field, message=None):
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self.queryset = queryset
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self.field = field
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self.date_field = date_field
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self.message = message or self.message
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def enforce_required_fields(self, attrs):
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"""
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The `UniqueFor<Range>Validator` classes always force an implied
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'required' state on the fields they are applied to.
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"""
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missing_items = {
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field_name: self.missing_message
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for field_name in [self.field, self.date_field]
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if field_name not in attrs
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}
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if missing_items:
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raise ValidationError(missing_items, code='required')
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def filter_queryset(self, attrs, queryset, field_name, date_field_name):
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raise NotImplementedError('`filter_queryset` must be implemented.')
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def exclude_current_instance(self, attrs, queryset, instance):
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"""
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If an instance is being updated, then do not include
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that instance itself as a uniqueness conflict.
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"""
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if instance is not None:
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return queryset.exclude(pk=instance.pk)
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return queryset
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def __call__(self, attrs, serializer):
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# Determine the underlying model field names. These may not be the
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# same as the serializer field names if `source=<>` is set.
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field_name = serializer.fields[self.field].source_attrs[-1]
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date_field_name = serializer.fields[self.date_field].source_attrs[-1]
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self.enforce_required_fields(attrs)
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queryset = self.queryset
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queryset = self.filter_queryset(attrs, queryset, field_name, date_field_name)
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queryset = self.exclude_current_instance(attrs, queryset, serializer.instance)
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if qs_exists(queryset):
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message = self.message.format(date_field=self.date_field)
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raise ValidationError({
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self.field: message
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}, code='unique')
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def __repr__(self):
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return '<%s(queryset=%s, field=%s, date_field=%s)>' % (
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self.__class__.__name__,
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smart_repr(self.queryset),
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smart_repr(self.field),
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smart_repr(self.date_field)
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)
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class UniqueForDateValidator(BaseUniqueForValidator):
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message = _('This field must be unique for the "{date_field}" date.')
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def filter_queryset(self, attrs, queryset, field_name, date_field_name):
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value = attrs[self.field]
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date = attrs[self.date_field]
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filter_kwargs = {}
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filter_kwargs[field_name] = value
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filter_kwargs['%s__day' % date_field_name] = date.day
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filter_kwargs['%s__month' % date_field_name] = date.month
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filter_kwargs['%s__year' % date_field_name] = date.year
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return qs_filter(queryset, **filter_kwargs)
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class UniqueForMonthValidator(BaseUniqueForValidator):
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message = _('This field must be unique for the "{date_field}" month.')
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def filter_queryset(self, attrs, queryset, field_name, date_field_name):
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value = attrs[self.field]
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date = attrs[self.date_field]
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filter_kwargs = {}
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filter_kwargs[field_name] = value
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filter_kwargs['%s__month' % date_field_name] = date.month
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return qs_filter(queryset, **filter_kwargs)
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class UniqueForYearValidator(BaseUniqueForValidator):
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message = _('This field must be unique for the "{date_field}" year.')
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def filter_queryset(self, attrs, queryset, field_name, date_field_name):
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value = attrs[self.field]
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date = attrs[self.date_field]
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filter_kwargs = {}
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filter_kwargs[field_name] = value
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filter_kwargs['%s__year' % date_field_name] = date.year
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return qs_filter(queryset, **filter_kwargs)
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