Fix validation for ListSerializer

rest_framework/serializers.py

@@ -609,6 +609,13 @@ def __init__(self, *args, **kwargs):
  self.min_length = kwargs.pop('min_length', None)
  assert self.child is not None, '`child` is a required argument.'
  assert not inspect.isclass(self.child), '`child` has not been instantiated.'
+
+ # instance, data = kwargs.get('instance', []), kwargs.get('data', []) # if you prefer one line assignment support
+ instance = kwargs.get('instance', [])
+ data = kwargs.get('data', [])
+ if instance and data:
+ assert len(data) == len(instance), 'Data and instance should have same length'
+
  super().__init__(*args, **kwargs)
  self.child.bind(field_name='', parent=self)
 
@@ -683,7 +690,13 @@ def to_internal_value(self, data):
  ret = []
  errors = []
 
- for item in data:
+ for idx, item in enumerate(data):
+ if (
+ hasattr(self, 'instance')
+ and self.instance
+ and len(self.instance) > idx
+ ):
+ self.child.instance = self.instance[idx]
  try:
  validated = self.child.run_validation(item)
  except ValidationError as exc:

tests/test_serializer.py

@@ -2,6 +2,7 @@
 import pickle
 import re
 import sys
+import unittest
 from collections import ChainMap
 from collections.abc import Mapping
 
@@ -783,3 +784,63 @@ def test_nested_key(self):
  ret = {'a': 1}
  self.s.set_value(ret, ['x', 'y'], 2)
  assert ret == {'a': 1, 'x': {'y': 2}}
+
+
+class MyClass(models.Model):
+ name = models.CharField(max_length=100)
+ value = models.CharField(max_length=100, blank=True)
+
+ app_label = "test"
+
+ @property
+ def is_valid(self):
+ return self.name == 'valid'
+
+
+class MyClassSerializer(serializers.ModelSerializer):
+ class Meta:
+ model = MyClass
+ fields = ('id', 'name', 'value')
+
+ def validate_value(self, value):
+ if value and not self.instance.is_valid:
+ raise serializers.ValidationError(
+ 'Status cannot be set for invalid instance')
+ return value
+
+
+class TestMultipleObjectsValidation(unittest.TestCase):
+ def setUp(self):
+ self.objs = [
+ MyClass(name='valid'),
+ MyClass(name='invalid'),
+ MyClass(name='other'),
+ ]
+
+ def test_multiple_objects_are_validated_separately(self):
+
+ serializer = MyClassSerializer(
+ data=[{'value': 'set', 'id': instance.id} for instance in
+ self.objs],
+ instance=self.objs,
+ many=True,
+ partial=True,
+ )
+
+ assert not serializer.is_valid()
+ assert serializer.errors == [
+ {},
+ {'value': ['Status cannot be set for invalid instance']},
+ {'value': ['Status cannot be set for invalid instance']}
+ ]
+
+ def test_exception_raised_when_data_and_instance_length_different(self):
+
+ with self.assertRaises(AssertionError):
+ MyClassSerializer(
+ data=[{'value': 'set', 'id': instance.id} for instance in
+ self.objs],
+ instance=self.objs[:-1],
+ many=True,
+ partial=True,
+ )