Ensure 'HStoreField' child is a 'CharField'

rest_framework/fields.py

@@ -1687,6 +1687,13 @@ class DictField(Field):
 class HStoreField(DictField):
     child = CharField(allow_blank=True, allow_null=True)
 
+    def __init__(self, *args, **kwargs):
+        super(HStoreField, self).__init__(*args, **kwargs)
+        assert isinstance(self.child, CharField), (
+            "The `child` argument must be an instance of `CharField`, "
+            "as the hstore extension stores values as strings."
+        )
+
 
 class JSONField(Field):
     default_error_messages = {

tests/test_fields.py

@@ -1913,6 +1913,15 @@ class TestHStoreField(FieldValues):
     ]
     field = serializers.HStoreField()
 
+    def test_child_is_charfield(self):
+        with pytest.raises(AssertionError) as exc_info:
+            serializers.HStoreField(child=serializers.IntegerField())
+
+        assert str(exc_info.value) == (
+            "The `child` argument must be an instance of `CharField`, "
+            "as the hstore extension stores values as strings."
+        )
+
     def test_no_source_on_child(self):
         with pytest.raises(AssertionError) as exc_info:
             serializers.HStoreField(child=serializers.CharField(source='other'))