Source code for django.contrib.postgres.fields.hstore

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.translation import ugettext_lazy as _

__all__ = ['HStoreField']


[docs]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):
        value = self._get_val_from_obj(obj)
        return json.dumps(value)

    def formfield(self, **kwargs):
        defaults = {
            'form_class': forms.HStoreField,
        }
        defaults.update(kwargs)
        return super(HStoreField, self).formfield(**defaults)


HStoreField.register_lookup(lookups.DataContains)
HStoreField.register_lookup(lookups.ContainedBy)


@HStoreField.register_lookup
class HasKeyLookup(lookups.PostgresSimpleLookup):
    lookup_name = 'has_key'
    operator = '?'


@HStoreField.register_lookup
class HasKeysLookup(lookups.PostgresSimpleLookup):
    lookup_name = 'has_keys'
    operator = '?&'


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(lookups.FunctionTransform):
    lookup_name = 'keys'
    function = 'akeys'
    output_field = ArrayField(TextField())


@HStoreField.register_lookup
class ValuesTransform(lookups.FunctionTransform):
    lookup_name = 'values'
    function = 'avals'
    output_field = ArrayField(TextField())