From a639a7c4a436bb1a666032f02354f78bf1242e68 Mon Sep 17 00:00:00 2001
From: Daniel Hahler <git@thequod.de>
Date: Wed, 30 May 2018 16:38:23 +0200
Subject: [PATCH] Fix DictField.get_value to return `empty`

Without this, an empty field is not considered to be empty and then
validators might fail, e.g.
django.contrib.postgres.validators.RangeMinValueValidator with

> E   TypeError: '<' not supported between instances of 'NoneType' and 'int'
---
 rest_framework/fields.py | 9 ++++++++-
 tests/test_fields.py     | 7 ++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 70c210c16..07bfb96f1 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -1708,10 +1708,17 @@ class DictField(Field):
         self.child.bind(field_name='', parent=self)
 
     def get_value(self, dictionary):
+        if self.field_name not in dictionary:
+            if getattr(self.root, 'partial', False):
+                return empty
         # We override the default field access in order to support
         # dictionaries in HTML forms.
         if html.is_html_input(dictionary):
-            return html.parse_html_dict(dictionary, prefix=self.field_name)
+            val = dictionary.getlist(self.field_name, {})
+            if len(val) > 0:
+                # Support QueryDict lists in HTML input.
+                return val
+            return html.parse_html_list(dictionary, prefix=self.field_name, default=empty)
         return dictionary.get(self.field_name, empty)
 
     def to_internal_value(self, data):
diff --git a/tests/test_fields.py b/tests/test_fields.py
index 9a1d04979..165641121 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -16,7 +16,7 @@ from django.utils.timezone import activate, deactivate, override, utc
 import rest_framework
 from rest_framework import exceptions, serializers
 from rest_framework.compat import ProhibitNullCharactersValidator
-from rest_framework.fields import DjangoImageField, is_simple_callable
+from rest_framework.fields import DjangoImageField, empty, is_simple_callable
 
 try:
     import typings
@@ -168,6 +168,11 @@ class TestEmpty:
         output = field.run_validation()
         assert output is 123
 
+    def test_dictfield_empty(self):
+        field = serializers.DictField()
+        field.field_name = 'dict_field'
+        assert field.get_value(QueryDict()) is empty
+
 
 class TestSource:
     def test_source(self):