Instead of using DjangoJSONEncoder, use base_field's value_to_string.

Note this means the serialization of e.g. IntegerRangeField now has
strings for lower and upper, so use to_python when they came back in
(same behaviour as ArrayField, hopefully, from where I also got the
set_attributes_from_name function).

django/contrib/postgres/fields/array.py

@@ -8,14 +8,11 @@ from django.db.models import Field, IntegerField, Transform
 from django.utils import six
 from django.utils.translation import string_concat, ugettext_lazy as _
 
+from .utils import AttributeSetter
+
 __all__ = ['ArrayField']
 
 
-class AttributeSetter(object):
-    def __init__(self, name, value):
-        setattr(self, name, value)
-
-
 class ArrayField(Field):
     empty_strings_allowed = False
     default_error_messages = {

django/contrib/postgres/fields/ranges.py

@@ -3,10 +3,11 @@ import json
 from psycopg2.extras import DateRange, DateTimeTZRange, NumericRange, Range
 
 from django.contrib.postgres import forms, lookups
-from django.core.serializers.json import DjangoJSONEncoder
 from django.db import models
 from django.utils import six
 
+from .utils import AttributeSetter
+
 __all__ = [
     'RangeField', 'IntegerRangeField', 'BigIntegerRangeField',
     'FloatRangeField', 'DateTimeRangeField', 'DateRangeField',
@@ -27,22 +28,32 @@ class RangeField(models.Field):
 
     def to_python(self, value):
         if isinstance(value, six.string_types):
-            value = self.range_type(**json.loads(value))
+            # Assume we're deserializing
+            vals = json.loads(value)
+            for end in ('lower', 'upper'):
+                if end in vals:
+                    vals[end] = self.base_field.to_python(vals[end])
+            value = self.range_type(**vals)
         elif isinstance(value, (list, tuple)):
             value = self.range_type(value[0], value[1])
         return value
 
+    def set_attributes_from_name(self, name):
+        super(RangeField, self).set_attributes_from_name(name)
+        self.base_field.set_attributes_from_name(name)
+
     def value_to_string(self, obj):
         value = self._get_val_from_obj(obj)
         if value is None:
             return None
         if value.isempty:
             return json.dumps({"empty": True})
-        return json.dumps({
+        base_field = self.base_field
-            "lower": value.lower,
+        result = {"bounds": value._bounds}
-            "upper": value.upper,
+        for end in ('lower', 'upper'):
-            "bounds": value._bounds,
+            obj = AttributeSetter(base_field.attname, getattr(value, end))
-        }, cls=DjangoJSONEncoder)
+            result[end] = base_field.value_to_string(obj)
+        return json.dumps(result)
 
     def formfield(self, **kwargs):
         kwargs.setdefault('form_class', self.form_field)

django/contrib/postgres/fields/utils.py

@@ -0,0 +1,3 @@
+class AttributeSetter(object):
+    def __init__(self, name, value):
+        setattr(self, name, value)

tests/postgres_tests/test_ranges.py

@@ -291,7 +291,7 @@ class TestQueringWithRanges(TestCase):
 @skipUnlessPG92
 class TestSerialization(TestCase):
     test_data = (
-        '[{"fields": {"ints": "{\\"upper\\": 10, \\"lower\\": 0, '
+        '[{"fields": {"ints": "{\\"upper\\": \\"10\\", \\"lower\\": \\"0\\", '
         '\\"bounds\\": \\"[)\\"}", "floats": "{\\"empty\\": true}", '
         '"bigints": null, "timestamps": "{\\"upper\\": \\"2014-02-02T12:12:12\\", '
         '\\"lower\\": \\"2014-01-01T00:00:00\\", \\"bounds\\": \\"[)\\"}", '