From d3430ce6d7c031499e30397e008aa06d5158af18 Mon Sep 17 00:00:00 2001
From: Andrew Backer <awbacker@gmail.com>
Date: Tue, 13 Feb 2018 15:37:33 +0800
Subject: [PATCH] Allow for indexed keys in list field default value check
 (?field[0]=)

---
 rest_framework/fields.py |  3 ++-
 tests/test_fields.py     | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 0684abfc2..ed34e5582 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -1610,7 +1610,8 @@ class ListField(Field):
         # lists in HTML forms.
         if html.is_html_input(dictionary):
             if self.field_name not in dictionary:
-                return empty
+                if not any(k.startswith("%s[" % self.field_name) for k in dictionary):
+                    return empty
             val = dictionary.getlist(self.field_name, [])
             if len(val) > 0:
                 # Support QueryDict lists in HTML input.
diff --git a/tests/test_fields.py b/tests/test_fields.py
index 03613bbf9..e57e0ab43 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -472,6 +472,18 @@ class TestHTMLInput:
         assert serializer.is_valid()
         assert serializer.validated_data == {'a': 1, 'scores': [1, 3]}
 
+    def test_querydict_list_input_supports_indexed_keys(self):
+        """
+        When data is passed in the format `scores[0]=1&scores[1]=3`
+        The field should return the correct list, ignoring the default
+        """
+        class TestSerializer(serializers.Serializer):
+            scores = serializers.ListField(default=lambda: [1, 3])
+
+        serializer = TestSerializer(data=QueryDict("scores[0]=5&scores[1]=6"))
+        assert serializer.is_valid()
+        assert serializer.validated_data == {'scores': ['5', '6']}
+
     def test_querydict_list_input_no_values_no_default_and_not_required(self):
         """
         When there are no keys passed, there is no default, and required=False
@@ -484,6 +496,19 @@ class TestHTMLInput:
         assert serializer.is_valid()
         assert serializer.validated_data == {}
 
+    def test_querydict_list_input_posts_key_but_no_values(self):
+        """
+        When there are no keys passed, there is no default, and required=False
+        The field should return an array of 1 item, blank
+        * Not sure if this is desired behavior, but it is logical at least
+        """
+        class TestSerializer(serializers.Serializer):
+            scores = serializers.ListField(required=False)
+
+        serializer = TestSerializer(data=QueryDict('scores=&'))
+        assert serializer.is_valid()
+        assert serializer.validated_data == {'scores': ['']}
+
 
 class TestCreateOnlyDefault:
     def setup(self):