From 6fda742b890e7fc86250fb0c55bbd75fb828f652 Mon Sep 17 00:00:00 2001
From: Ryan P Kilby <rpkilby@ncsu.edu>
Date: Tue, 5 Dec 2017 00:35:48 -0500
Subject: [PATCH] Add HStoreField

---
 rest_framework/fields.py       |  4 ++++
 rest_framework/serializers.py  | 11 ++++-------
 tests/test_fields.py           | 34 ++++++++++++++++++++++++++++++++++
 tests/test_model_serializer.py |  2 +-
 4 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index a710df7b4..b39f394f6 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -1684,6 +1684,10 @@ class DictField(Field):
         }
 
 
+class HStoreField(DictField):
+    child = CharField(allow_blank=True, allow_null=True)
+
+
 class JSONField(Field):
     default_error_messages = {
         'invalid': _('Value must be valid JSON.')
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index e2ea0d744..69341d51e 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -54,9 +54,9 @@ from rest_framework.validators import (
 from rest_framework.fields import (  # NOQA # isort:skip
     BooleanField, CharField, ChoiceField, DateField, DateTimeField, DecimalField,
     DictField, DurationField, EmailField, Field, FileField, FilePathField, FloatField,
-    HiddenField, IPAddressField, ImageField, IntegerField, JSONField, ListField,
-    ModelField, MultipleChoiceField, NullBooleanField, ReadOnlyField, RegexField,
-    SerializerMethodField, SlugField, TimeField, URLField, UUIDField,
+    HiddenField, HStoreField, IPAddressField, ImageField, IntegerField, JSONField,
+    ListField, ModelField, MultipleChoiceField, NullBooleanField, ReadOnlyField,
+    RegexField, SerializerMethodField, SlugField, TimeField, URLField, UUIDField,
 )
 from rest_framework.relations import (  # NOQA # isort:skip
     HyperlinkedIdentityField, HyperlinkedRelatedField, ManyRelatedField,
@@ -1541,10 +1541,7 @@ if hasattr(models, 'IPAddressField'):
     ModelSerializer.serializer_field_mapping[models.IPAddressField] = IPAddressField
 
 if postgres_fields:
-    class CharMappingField(DictField):
-        child = CharField(allow_blank=True)
-
-    ModelSerializer.serializer_field_mapping[postgres_fields.HStoreField] = CharMappingField
+    ModelSerializer.serializer_field_mapping[postgres_fields.HStoreField] = HStoreField
     ModelSerializer.serializer_field_mapping[postgres_fields.ArrayField] = ListField
     ModelSerializer.serializer_field_mapping[postgres_fields.JSONField] = JSONField
 
diff --git a/tests/test_fields.py b/tests/test_fields.py
index fc9ce192a..88bf21678 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -1897,6 +1897,40 @@ class TestUnvalidatedDictField(FieldValues):
     field = serializers.DictField()
 
 
+class TestHStoreField(FieldValues):
+    """
+    Values for `ListField` with CharField as child.
+    """
+    valid_inputs = [
+        ({'a': 1, 'b': '2', 3: 3}, {'a': '1', 'b': '2', '3': '3'}),
+        ({'a': 1, 'b': None}, {'a': '1', 'b': None}),
+    ]
+    invalid_inputs = [
+        ('not a dict', ['Expected a dictionary of items but got type "str".']),
+    ]
+    outputs = [
+        ({'a': 1, 'b': '2', 3: 3}, {'a': '1', 'b': '2', '3': '3'}),
+    ]
+    field = serializers.HStoreField()
+
+    def test_no_source_on_child(self):
+        with pytest.raises(AssertionError) as exc_info:
+            serializers.HStoreField(child=serializers.CharField(source='other'))
+
+        assert str(exc_info.value) == (
+            "The `source` argument is not meaningful when applied to a `child=` field. "
+            "Remove `source=` from the field declaration."
+        )
+
+    def test_allow_null(self):
+        """
+        If `allow_null=True` then `None` is a valid input.
+        """
+        field = serializers.HStoreField(allow_null=True)
+        output = field.run_validation(None)
+        assert output is None
+
+
 class TestJSONField(FieldValues):
     """
     Values for `JSONField`.
diff --git a/tests/test_model_serializer.py b/tests/test_model_serializer.py
index 72011c447..e55afe03e 100644
--- a/tests/test_model_serializer.py
+++ b/tests/test_model_serializer.py
@@ -392,7 +392,7 @@ class TestPosgresFieldsMapping(TestCase):
 
         expected = dedent("""
             TestSerializer():
-                hstore_field = CharMappingField()
+                hstore_field = HStoreField()
         """)
         self.assertEqual(unicode_repr(TestSerializer()), expected)