Code source de django.contrib.postgres.fields.array
import json
from django.contrib.postgres import lookups
from django.contrib.postgres.forms import SimpleArrayField
from django.contrib.postgres.validators import ArrayMaxLengthValidator
from django.core import checks, exceptions
from django.db.models import Field, IntegerField, Transform
from django.db.models.lookups import Exact, In
from django.utils.inspect import func_supports_parameter
from django.utils.translation import gettext_lazy as _
from ..utils import prefix_validation_error
from .mixins import CheckFieldDefaultMixin
from .utils import AttributeSetter
__all__ = ['ArrayField']
[docs]class ArrayField(CheckFieldDefaultMixin, Field):
empty_strings_allowed = False
default_error_messages = {
'item_invalid': _('Item %(nth)s in the array did not validate:'),
'nested_array_mismatch': _('Nested arrays must have the same length.'),
}
_default_hint = ('list', '[]')
def __init__(self, base_field, size=None, **kwargs):
self.base_field = base_field
self.size = size
if self.size:
self.default_validators = self.default_validators[:]
self.default_validators.append(ArrayMaxLengthValidator(self.size))
# For performance, only add a from_db_value() method if the base field
# implements it.
if hasattr(self.base_field, 'from_db_value'):
self.from_db_value = self._from_db_value
super().__init__(**kwargs)
@property
def model(self):
try:
return self.__dict__['model']
except KeyError:
raise AttributeError("'%s' object has no attribute 'model'" % self.__class__.__name__)
@model.setter
def model(self, model):
self.__dict__['model'] = model
self.base_field.model = model
def check(self, **kwargs):
errors = super().check(**kwargs)
if self.base_field.remote_field:
errors.append(
checks.Error(
'Base field for array cannot be a related field.',
obj=self,
id='postgres.E002'
)
)
else:
# Remove the field name checks as they are not needed here.
base_errors = self.base_field.check()
if base_errors:
messages = '\n '.join('%s (%s)' % (error.msg, error.id) for error in base_errors)
errors.append(
checks.Error(
'Base field for array has errors:\n %s' % messages,
obj=self,
id='postgres.E001'
)
)
return errors
def set_attributes_from_name(self, name):
super().set_attributes_from_name(name)
self.base_field.set_attributes_from_name(name)
@property
def description(self):
return 'Array of %s' % self.base_field.description
def db_type(self, connection):
size = self.size or ''
return '%s[%s]' % (self.base_field.db_type(connection), size)
def get_db_prep_value(self, value, connection, prepared=False):
if isinstance(value, (list, tuple)):
return [self.base_field.get_db_prep_value(i, connection, prepared=False) for i in value]
return value
def deconstruct(self):
name, path, args, kwargs = super().deconstruct()
if path == 'django.contrib.postgres.fields.array.ArrayField':
path = 'django.contrib.postgres.fields.ArrayField'
kwargs.update({
'base_field': self.base_field.clone(),
'size': self.size,
})
return name, path, args, kwargs
def to_python(self, value):
if isinstance(value, str):
# Assume we're deserializing
vals = json.loads(value)
value = [self.base_field.to_python(val) for val in vals]
return value
def _from_db_value(self, value, expression, connection):
if value is None:
return value
return [
self.base_field.from_db_value(item, expression, connection, {})
if func_supports_parameter(self.base_field.from_db_value, 'context') # RemovedInDjango30Warning
else self.base_field.from_db_value(item, expression, connection)
for item in value
]
def value_to_string(self, obj):
values = []
vals = self.value_from_object(obj)
base_field = self.base_field
for val in vals:
if val is None:
values.append(None)
else:
obj = AttributeSetter(base_field.attname, val)
values.append(base_field.value_to_string(obj))
return json.dumps(values)
def get_transform(self, name):
transform = super().get_transform(name)
if transform:
return transform
if '_' not in name:
try:
index = int(name)
except ValueError:
pass
else:
index += 1 # postgres uses 1-indexing
return IndexTransformFactory(index, self.base_field)
try:
start, end = name.split('_')
start = int(start) + 1
end = int(end) # don't add one here because postgres slices are weird
except ValueError:
pass
else:
return SliceTransformFactory(start, end)
def validate(self, value, model_instance):
super().validate(value, model_instance)
for index, part in enumerate(value):
try:
self.base_field.validate(part, model_instance)
except exceptions.ValidationError as error:
raise prefix_validation_error(
error,
prefix=self.error_messages['item_invalid'],
code='item_invalid',
params={'nth': index + 1},
)
if isinstance(self.base_field, ArrayField):
if len({len(i) for i in value}) > 1:
raise exceptions.ValidationError(
self.error_messages['nested_array_mismatch'],
code='nested_array_mismatch',
)
def run_validators(self, value):
super().run_validators(value)
for index, part in enumerate(value):
try:
self.base_field.run_validators(part)
except exceptions.ValidationError as error:
raise prefix_validation_error(
error,
prefix=self.error_messages['item_invalid'],
code='item_invalid',
params={'nth': index + 1},
)
def formfield(self, **kwargs):
return super().formfield(**{
'form_class': SimpleArrayField,
'base_field': self.base_field.formfield(),
'max_length': self.size,
**kwargs,
})
@ArrayField.register_lookup
class ArrayContains(lookups.DataContains):
def as_sql(self, qn, connection):
sql, params = super().as_sql(qn, connection)
sql = '%s::%s' % (sql, self.lhs.output_field.db_type(connection))
return sql, params
@ArrayField.register_lookup
class ArrayContainedBy(lookups.ContainedBy):
def as_sql(self, qn, connection):
sql, params = super().as_sql(qn, connection)
sql = '%s::%s' % (sql, self.lhs.output_field.db_type(connection))
return sql, params
@ArrayField.register_lookup
class ArrayExact(Exact):
def as_sql(self, qn, connection):
sql, params = super().as_sql(qn, connection)
sql = '%s::%s' % (sql, self.lhs.output_field.db_type(connection))
return sql, params
@ArrayField.register_lookup
class ArrayOverlap(lookups.Overlap):
def as_sql(self, qn, connection):
sql, params = super().as_sql(qn, connection)
sql = '%s::%s' % (sql, self.lhs.output_field.db_type(connection))
return sql, params
@ArrayField.register_lookup
class ArrayLenTransform(Transform):
lookup_name = 'len'
output_field = IntegerField()
def as_sql(self, compiler, connection):
lhs, params = compiler.compile(self.lhs)
# Distinguish NULL and empty arrays
return (
'CASE WHEN %(lhs)s IS NULL THEN NULL ELSE '
'coalesce(array_length(%(lhs)s, 1), 0) END'
) % {'lhs': lhs}, params
@ArrayField.register_lookup
class ArrayInLookup(In):
def get_prep_lookup(self):
values = super().get_prep_lookup()
if hasattr(self.rhs, '_prepare'):
# Subqueries don't need further preparation.
return values
# In.process_rhs() expects values to be hashable, so convert lists
# to tuples.
prepared_values = []
for value in values:
if hasattr(value, 'resolve_expression'):
prepared_values.append(value)
else:
prepared_values.append(tuple(value))
return prepared_values
class IndexTransform(Transform):
def __init__(self, index, base_field, *args, **kwargs):
super().__init__(*args, **kwargs)
self.index = index
self.base_field = base_field
def as_sql(self, compiler, connection):
lhs, params = compiler.compile(self.lhs)
return '%s[%s]' % (lhs, self.index), params
@property
def output_field(self):
return self.base_field
class IndexTransformFactory:
def __init__(self, index, base_field):
self.index = index
self.base_field = base_field
def __call__(self, *args, **kwargs):
return IndexTransform(self.index, self.base_field, *args, **kwargs)
class SliceTransform(Transform):
def __init__(self, start, end, *args, **kwargs):
super().__init__(*args, **kwargs)
self.start = start
self.end = end
def as_sql(self, compiler, connection):
lhs, params = compiler.compile(self.lhs)
return '%s[%s:%s]' % (lhs, self.start, self.end), params
class SliceTransformFactory:
def __init__(self, start, end):
self.start = start
self.end = end
def __call__(self, *args, **kwargs):
return SliceTransform(self.start, self.end, *args, **kwargs)
