Fixed #24844 -- Corrected has_changed implementation for HStoreField.

        for key, val in value.items():

            value[key] = six.text_type(val)

        return value

    def has_changed(self, initial, data):

        """

        Return True if data differs from initial.

        """

        # For purposes of seeing whether something has changed, None is

        # the same as an empty dict, if the data or initial value we get

        # is None, replace it w/ {}.

        initial_value = self.to_python(initial)

        return super(forms.HStoreField, self).has_changed(initial_value, data)

* Fixed crash during :djadmin:`makemigrations` if a migrations module either

  is missing ``__init__.py`` or is a file (:ticket:`24848`).

* Fixed ``exists()`` returning incorrect results after annotation with

* Fixed ``QuerySet.exists()`` returning incorrect results after annotation with

  ``Count()`` (:ticket:`24835`).

* Corrected ``HStoreField.has_changed()`` (:ticket:`24844`).

from django.contrib.postgres.fields import HStoreField

from django.contrib.postgres.validators import KeysValidator

from django.core import exceptions, serializers

from django.forms import Form

from django.test import TestCase

from .models import HStoreModel

        form_field = model_field.formfield()

        self.assertIsInstance(form_field, forms.HStoreField)

    def test_empty_field_has_not_changed(self):

        class HStoreFormTest(Form):

            f1 = HStoreField()

        form_w_hstore = HStoreFormTest()

        self.assertFalse(form_w_hstore.has_changed())

class TestValidator(TestCase):