320 lines
10 KiB
Python
320 lines
10 KiB
Python
import json
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from django.contrib.postgres import lookups
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from django.contrib.postgres.forms import SimpleArrayField
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from django.contrib.postgres.validators import ArrayMaxLengthValidator
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from django.core import checks, exceptions
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from django.db.models import Field, Func, IntegerField, Transform, Value
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from django.db.models.fields.mixins import CheckFieldDefaultMixin
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from django.db.models.lookups import Exact, In
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from django.utils.translation import gettext_lazy as _
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from ..utils import prefix_validation_error
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from .utils import AttributeSetter
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__all__ = ['ArrayField']
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class ArrayField(CheckFieldDefaultMixin, Field):
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empty_strings_allowed = False
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default_error_messages = {
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'item_invalid': _('Item %(nth)s in the array did not validate:'),
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'nested_array_mismatch': _('Nested arrays must have the same length.'),
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}
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_default_hint = ('list', '[]')
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def __init__(self, base_field, size=None, **kwargs):
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self.base_field = base_field
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self.size = size
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if self.size:
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self.default_validators = [*self.default_validators, ArrayMaxLengthValidator(self.size)]
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# For performance, only add a from_db_value() method if the base field
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# implements it.
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if hasattr(self.base_field, 'from_db_value'):
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self.from_db_value = self._from_db_value
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super().__init__(**kwargs)
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@property
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def model(self):
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try:
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return self.__dict__['model']
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except KeyError:
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raise AttributeError("'%s' object has no attribute 'model'" % self.__class__.__name__)
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@model.setter
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def model(self, model):
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self.__dict__['model'] = model
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self.base_field.model = model
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@classmethod
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def _choices_is_value(cls, value):
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return isinstance(value, (list, tuple)) or super()._choices_is_value(value)
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def check(self, **kwargs):
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errors = super().check(**kwargs)
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if self.base_field.remote_field:
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errors.append(
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checks.Error(
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'Base field for array cannot be a related field.',
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obj=self,
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id='postgres.E002'
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)
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)
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else:
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# Remove the field name checks as they are not needed here.
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base_errors = self.base_field.check()
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if base_errors:
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messages = '\n '.join('%s (%s)' % (error.msg, error.id) for error in base_errors)
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errors.append(
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checks.Error(
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'Base field for array has errors:\n %s' % messages,
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obj=self,
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id='postgres.E001'
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)
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)
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return errors
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def set_attributes_from_name(self, name):
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super().set_attributes_from_name(name)
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self.base_field.set_attributes_from_name(name)
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@property
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def description(self):
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return 'Array of %s' % self.base_field.description
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def db_type(self, connection):
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size = self.size or ''
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return '%s[%s]' % (self.base_field.db_type(connection), size)
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def cast_db_type(self, connection):
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size = self.size or ''
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return '%s[%s]' % (self.base_field.cast_db_type(connection), size)
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def get_placeholder(self, value, compiler, connection):
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return '%s::{}'.format(self.db_type(connection))
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def get_db_prep_value(self, value, connection, prepared=False):
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if isinstance(value, (list, tuple)):
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return [self.base_field.get_db_prep_value(i, connection, prepared=False) for i in value]
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return value
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def deconstruct(self):
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name, path, args, kwargs = super().deconstruct()
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if path == 'django.contrib.postgres.fields.array.ArrayField':
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path = 'django.contrib.postgres.fields.ArrayField'
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kwargs.update({
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'base_field': self.base_field.clone(),
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'size': self.size,
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})
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return name, path, args, kwargs
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def to_python(self, value):
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if isinstance(value, str):
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# Assume we're deserializing
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vals = json.loads(value)
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value = [self.base_field.to_python(val) for val in vals]
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return value
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def _from_db_value(self, value, expression, connection):
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if value is None:
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return value
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return [
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self.base_field.from_db_value(item, expression, connection)
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for item in value
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]
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def value_to_string(self, obj):
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values = []
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vals = self.value_from_object(obj)
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base_field = self.base_field
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for val in vals:
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if val is None:
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values.append(None)
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else:
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obj = AttributeSetter(base_field.attname, val)
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values.append(base_field.value_to_string(obj))
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return json.dumps(values)
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def get_transform(self, name):
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transform = super().get_transform(name)
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if transform:
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return transform
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if '_' not in name:
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try:
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index = int(name)
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except ValueError:
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pass
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else:
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index += 1 # postgres uses 1-indexing
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return IndexTransformFactory(index, self.base_field)
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try:
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start, end = name.split('_')
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start = int(start) + 1
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end = int(end) # don't add one here because postgres slices are weird
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except ValueError:
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pass
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else:
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return SliceTransformFactory(start, end)
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def validate(self, value, model_instance):
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super().validate(value, model_instance)
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for index, part in enumerate(value):
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try:
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self.base_field.validate(part, model_instance)
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except exceptions.ValidationError as error:
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raise prefix_validation_error(
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error,
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prefix=self.error_messages['item_invalid'],
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code='item_invalid',
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params={'nth': index + 1},
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)
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if isinstance(self.base_field, ArrayField):
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if len({len(i) for i in value}) > 1:
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raise exceptions.ValidationError(
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self.error_messages['nested_array_mismatch'],
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code='nested_array_mismatch',
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)
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def run_validators(self, value):
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super().run_validators(value)
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for index, part in enumerate(value):
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try:
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self.base_field.run_validators(part)
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except exceptions.ValidationError as error:
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raise prefix_validation_error(
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error,
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prefix=self.error_messages['item_invalid'],
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code='item_invalid',
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params={'nth': index + 1},
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)
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def formfield(self, **kwargs):
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return super().formfield(**{
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'form_class': SimpleArrayField,
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'base_field': self.base_field.formfield(),
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'max_length': self.size,
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**kwargs,
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})
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class ArrayRHSMixin:
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def __init__(self, lhs, rhs):
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if isinstance(rhs, (tuple, list)):
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expressions = []
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for value in rhs:
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if not hasattr(value, 'resolve_expression'):
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field = lhs.output_field
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value = Value(field.base_field.get_prep_value(value))
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expressions.append(value)
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rhs = Func(
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*expressions,
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function='ARRAY',
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template='%(function)s[%(expressions)s]',
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)
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super().__init__(lhs, rhs)
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def process_rhs(self, compiler, connection):
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rhs, rhs_params = super().process_rhs(compiler, connection)
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cast_type = self.lhs.output_field.cast_db_type(connection)
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return '%s::%s' % (rhs, cast_type), rhs_params
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@ArrayField.register_lookup
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class ArrayContains(ArrayRHSMixin, lookups.DataContains):
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pass
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@ArrayField.register_lookup
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class ArrayContainedBy(ArrayRHSMixin, lookups.ContainedBy):
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pass
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@ArrayField.register_lookup
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class ArrayExact(ArrayRHSMixin, Exact):
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pass
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@ArrayField.register_lookup
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class ArrayOverlap(ArrayRHSMixin, lookups.Overlap):
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pass
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@ArrayField.register_lookup
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class ArrayLenTransform(Transform):
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lookup_name = 'len'
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output_field = IntegerField()
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def as_sql(self, compiler, connection):
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lhs, params = compiler.compile(self.lhs)
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# Distinguish NULL and empty arrays
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return (
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'CASE WHEN %(lhs)s IS NULL THEN NULL ELSE '
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'coalesce(array_length(%(lhs)s, 1), 0) END'
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) % {'lhs': lhs}, params
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@ArrayField.register_lookup
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class ArrayInLookup(In):
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def get_prep_lookup(self):
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values = super().get_prep_lookup()
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if hasattr(values, 'resolve_expression'):
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return values
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# In.process_rhs() expects values to be hashable, so convert lists
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# to tuples.
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prepared_values = []
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for value in values:
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if hasattr(value, 'resolve_expression'):
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prepared_values.append(value)
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else:
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prepared_values.append(tuple(value))
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return prepared_values
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class IndexTransform(Transform):
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def __init__(self, index, base_field, *args, **kwargs):
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super().__init__(*args, **kwargs)
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self.index = index
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self.base_field = base_field
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def as_sql(self, compiler, connection):
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lhs, params = compiler.compile(self.lhs)
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return '%s[%%s]' % lhs, params + [self.index]
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@property
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def output_field(self):
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return self.base_field
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class IndexTransformFactory:
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def __init__(self, index, base_field):
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self.index = index
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self.base_field = base_field
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def __call__(self, *args, **kwargs):
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return IndexTransform(self.index, self.base_field, *args, **kwargs)
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class SliceTransform(Transform):
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def __init__(self, start, end, *args, **kwargs):
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super().__init__(*args, **kwargs)
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self.start = start
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self.end = end
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def as_sql(self, compiler, connection):
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lhs, params = compiler.compile(self.lhs)
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return '%s[%%s:%%s]' % lhs, params + [self.start, self.end]
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class SliceTransformFactory:
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def __init__(self, start, end):
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self.start = start
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self.end = end
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def __call__(self, *args, **kwargs):
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return SliceTransform(self.start, self.end, *args, **kwargs)
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