django-rest-framework/rest_framework/validators.py

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