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import json
from django.contrib.postgres import forms, lookups
from django.contrib.postgres.fields.array import ArrayField
from django.core import exceptions
from django.db.models import Field, TextField, Transform
from django.utils import six
from django.utils.encoding import force_text
from django.utils.translation import ugettext_lazy as _
__all__ = ['HStoreField']
class HStoreField(Field):
empty_strings_allowed = False
description = _('Map of strings to strings')
default_error_messages = {
'not_a_string': _('The value of "%(key)s" is not a string.'),
}
def db_type(self, connection):
return 'hstore'
def get_transform(self, name):
transform = super(HStoreField, self).get_transform(name)
if transform:
return transform
return KeyTransformFactory(name)
def validate(self, value, model_instance):
super(HStoreField, self).validate(value, model_instance)
for key, val in value.items():
if not isinstance(val, six.string_types):
raise exceptions.ValidationError(
self.error_messages['not_a_string'],
code='not_a_string',
params={'key': key},
)
def to_python(self, value):
if isinstance(value, six.string_types):
value = json.loads(value)
return value
def value_to_string(self, obj):
return json.dumps(self.value_from_object(obj))
def formfield(self, **kwargs):
defaults = {
'form_class': forms.HStoreField,
}
defaults.update(kwargs)
return super(HStoreField, self).formfield(**defaults)
def get_prep_value(self, value):
value = super(HStoreField, self).get_prep_value(value)
if isinstance(value, dict):
prep_value = {}
for key, val in value.items():
key = force_text(key)
if val is not None:
val = force_text(val)
prep_value[key] = val
value = prep_value
if isinstance(value, list):
value = [force_text(item) for item in value]
return value
HStoreField.register_lookup(lookups.DataContains)
HStoreField.register_lookup(lookups.ContainedBy)
HStoreField.register_lookup(lookups.HasKey)
HStoreField.register_lookup(lookups.HasKeys)
HStoreField.register_lookup(lookups.HasAnyKeys)
class KeyTransform(Transform):
output_field = TextField()
def __init__(self, key_name, *args, **kwargs):
super(KeyTransform, self).__init__(*args, **kwargs)
self.key_name = key_name
def as_sql(self, compiler, connection):
lhs, params = compiler.compile(self.lhs)
return '(%s -> %%s)' % lhs, [self.key_name] + params
class KeyTransformFactory(object):
def __init__(self, key_name):
self.key_name = key_name
def __call__(self, *args, **kwargs):
return KeyTransform(self.key_name, *args, **kwargs)
@HStoreField.register_lookup
class KeysTransform(Transform):
lookup_name = 'keys'
function = 'akeys'
output_field = ArrayField(TextField())
@HStoreField.register_lookup
class ValuesTransform(Transform):
lookup_name = 'values'
function = 'avals'
output_field = ArrayField(TextField())
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