From 417fe1b675bd1d42518fb89a6f81547caef5b735 Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Thu, 25 Sep 2014 13:37:26 +0100
Subject: [PATCH] Partial support

---
 rest_framework/fields.py      | 35 +++++++++++++++++++++++++----------
 rest_framework/serializers.py |  6 ++++--
 tests/test_serializer.py      | 33 ++++++++++++++++++++++++++++++++-
 3 files changed, 61 insertions(+), 13 deletions(-)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 7beccbb71..032bfd048 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -109,8 +109,7 @@ class Field(object):
     def __init__(self, read_only=False, write_only=False,
                  required=None, default=empty, initial=None, source=None,
                  label=None, help_text=None, style=None,
-                 error_messages=None, validators=[], allow_null=False,
-                 context=None):
+                 error_messages=None, validators=[], allow_null=False):
         self._creation_counter = Field._creation_counter
         Field._creation_counter += 1
 
@@ -139,7 +138,6 @@ class Field(object):
         # These are set up by `.bind()` when the field is added to a serializer.
         self.field_name = None
         self.parent = None
-        self._context = {} if (context is None) else context
 
         # Collect default error message from self and parent classes
         messages = {}
@@ -163,13 +161,6 @@ class Field(object):
         kwargs = copy.deepcopy(self._kwargs)
         return self.__class__(*args, **kwargs)
 
-    @property
-    def context(self):
-        root = self
-        while root.parent is not None:
-            root = root.parent
-        return root._context
-
     def bind(self, field_name, parent):
         """
         Setup the context for the field instance.
@@ -254,6 +245,8 @@ class Field(object):
         """
         if data is empty:
             if self.required:
+                if getattr(self.root, 'partial', False):
+                    raise SkipField()
                 self.fail('required')
             return self.get_default()
 
@@ -304,7 +297,29 @@ class Field(object):
             raise AssertionError(msg)
         raise ValidationError(msg.format(**kwargs))
 
+    @property
+    def root(self):
+        """
+        Returns the top-level serializer for this field.
+        """
+        root = self
+        while root.parent is not None:
+            root = root.parent
+        return root
+
+    @property
+    def context(self):
+        """
+        Returns the context as passed to the root serializer on initialization.
+        """
+        return getattr(self.root, '_context', {})
+
     def __repr__(self):
+        """
+        Fields are represented using their initial calling arguments.
+        This allows us to create descriptive representations for serializer
+        instances that show all the declared fields on the serializer.
+        """
         return representation.field_repr(self)
 
 
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 04721c7a3..b6a1898ca 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -181,8 +181,9 @@ class BindingDict(object):
 @six.add_metaclass(SerializerMetaclass)
 class Serializer(BaseSerializer):
     def __init__(self, *args, **kwargs):
-        kwargs.pop('partial', None)
         kwargs.pop('many', None)
+        self.partial = kwargs.pop('partial', False)
+        self._context = kwargs.pop('context', {})
 
         super(Serializer, self).__init__(*args, **kwargs)
 
@@ -289,7 +290,8 @@ class ListSerializer(BaseSerializer):
         self.child = kwargs.pop('child', copy.deepcopy(self.child))
         assert self.child is not None, '`child` is a required argument.'
         assert not inspect.isclass(self.child), '`child` has not been instantiated.'
-        kwargs.pop('partial', None)
+        self.partial = kwargs.pop('partial', False)
+        self._context = kwargs.pop('context', {})
 
         super(ListSerializer, self).__init__(*args, **kwargs)
         self.child.bind(field_name='', parent=self)
diff --git a/tests/test_serializer.py b/tests/test_serializer.py
index b0eb4e270..5646f9940 100644
--- a/tests/test_serializer.py
+++ b/tests/test_serializer.py
@@ -1,3 +1,35 @@
+from rest_framework import serializers
+
+
+# Tests for core functionality.
+# -----------------------------
+
+class TestSerializer:
+    def setup(self):
+        class ExampleSerializer(serializers.Serializer):
+            char = serializers.CharField()
+            integer = serializers.IntegerField()
+        self.Serializer = ExampleSerializer
+
+    def test_valid_serializer(self):
+        serializer = self.Serializer(data={'char': 'abc', 'integer': 123})
+        assert serializer.is_valid()
+        assert serializer.validated_data == {'char': 'abc', 'integer': 123}
+        assert serializer.errors == {}
+
+    def test_invalid_serializer(self):
+        serializer = self.Serializer(data={'char': 'abc'})
+        assert not serializer.is_valid()
+        assert serializer.validated_data == {}
+        assert serializer.errors == {'integer': ['This field is required.']}
+
+    def test_partial_validation(self):
+        serializer = self.Serializer(data={'char': 'abc'}, partial=True)
+        assert serializer.is_valid()
+        assert serializer.validated_data == {'char': 'abc'}
+        assert serializer.errors == {}
+
+
 # # -*- coding: utf-8 -*-
 # from __future__ import unicode_literals
 # from django.db import models
@@ -334,7 +366,6 @@
 #         Check _data attribute is cleared on `save()`
 
 #         Regression test for #1116
-#             — id field is not populated if `data` is accessed prior to `save()`
 #         """
 #         serializer = ActionItemSerializer(self.actionitem)
 #         self.assertIsNone(serializer.data.get('id', None), 'New instance. `id` should not be set.')