Added write_only and write_only_fields. Refs #1306

6 files changed, 117 insertions, 13 deletions

diff --git a/docs/api-guide/fields.md b/docs/api-guide/fields.md
index 91866664..c136509b 100644
--- a/docs/api-guide/fields.md
+++ b/docs/api-guide/fields.md
@@ -28,7 +28,13 @@ Defaults to the name of the field.
 
 ### `read_only`
 
-Set this to `True` to ensure that the field is used when serializing a representation, but is not used when updating an instance during deserialization.
+Set this to `True` to ensure that the field is used when serializing a representation, but is not used when creating or updating an instance during deserialization.
+
+Defaults to `False`
+
+### `write_only`
+
+Set this to `True` to ensure that the field may be used when updating or creating an instance, but is not included when serializing the representation.
 
 Defaults to `False`
 
diff --git a/docs/api-guide/serializers.md b/docs/api-guide/serializers.md
index 04439092..b05acfd5 100644
--- a/docs/api-guide/serializers.md
+++ b/docs/api-guide/serializers.md
@@ -373,6 +373,25 @@ You may wish to specify multiple fields as read-only.  Instead of adding each fi
 
 Model fields which have `editable=False` set, and `AutoField` fields will be set to read-only by default, and do not need to be added to the `read_only_fields` option. 
 
+## Specifying which fields should be write-only 
+
+You may wish to specify multiple fields as write-only.  Instead of adding each field explicitly with the `write_only=True` attribute, you may use the `write_only_fields` Meta option, like so:
+
+    class CreateUserSerializer(serializers.ModelSerializer):
+        class Meta:
+            model = User
+            fields = ('email', 'username', 'password')
+            write_only_fields = ('password',)  # Note: Password field is write-only
+
+    def restore_object(self, attrs, instance=None):
+        """
+        Instantiate a new User instance.
+        """
+        assert instance is None, 'Cannot update users with CreateUserSerializer'                                
+        user = User(email=attrs['email'], username=attrs['username'])
+        user.set_password(attrs['password'])
+        return user
+ 
 ## Specifying fields explicitly 
 
 You can add extra fields to a `ModelSerializer` or override the default fields by declaring fields on the class, just as you would for a `Serializer` class.
diff --git a/docs/topics/release-notes.md b/docs/topics/release-notes.md
index ca966d20..cd87c7b2 100644
--- a/docs/topics/release-notes.md
+++ b/docs/topics/release-notes.md
@@ -40,8 +40,12 @@ You can determine your currently installed version using `pip freeze`:
 
 ## 2.3.x series
 
-### Master
+### 2.3.11
 
+**Date**: 14th January 2014
+
+* Added `write_only` serializer field argument.
+* Added `write_only_fields` option to `ModelSerializer` classes.
 * JSON renderer now deals with objects that implement a dict-like interface.
 * Fix compatiblity with newer versions of `django-oauth-plus`.
 * Bugfix: Refine behavior that calls model manager `all()` across nested serializer relationships, preventing erronous behavior with some non-ORM objects, and preventing unneccessary queryset re-evaluations.
diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index f1de447c..258c0f6a 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -114,6 +114,10 @@ def strip_multiple_choice_msg(help_text):
     return help_text.replace(multiple_choice_msg, '')
 
 
+class IgnoreFieldException(Exception):
+    pass
+
+
 class Field(object):
     read_only = True
     creation_counter = 0
@@ -246,6 +250,7 @@ class WritableField(Field):
     """
     Base for read/write fields.
     """
+    write_only = False
     default_validators = []
     default_error_messages = {
         'required': _('This field is required.'),
@@ -255,7 +260,7 @@ class WritableField(Field):
     default = None
 
     def __init__(self, source=None, label=None, help_text=None,
-                 read_only=False, required=None,
+                 read_only=False, write_only=False, required=None,
                  validators=[], error_messages=None, widget=None,
                  default=None, blank=None):
 
@@ -269,6 +274,10 @@ class WritableField(Field):
         super(WritableField, self).__init__(source=source, label=label, help_text=help_text)
 
         self.read_only = read_only
+        self.write_only = write_only
+
+        assert not (read_only and write_only), "Cannot set read_only=True and write_only=True"
+
         if required is None:
             self.required = not(read_only)
         else:
@@ -318,6 +327,11 @@ class WritableField(Field):
         if errors:
             raise ValidationError(errors)
 
+    def field_to_native(self, obj, field_name):
+        if self.write_only:
+            raise IgnoreFieldException()
+        return super(WritableField, self).field_to_native(obj, field_name)
+
     def field_from_native(self, data, files, field_name, into):
         """
         Given a dictionary and a field name, updates the dictionary `into`,
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index b4087e54..9f047b03 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -344,7 +344,10 @@ class BaseSerializer(WritableField):
                continue
             field.initialize(parent=self, field_name=field_name)
             key = self.get_field_key(field_name)
-            value = field.field_to_native(obj, field_name)
+            try:
+                value = field.field_to_native(obj, field_name)
+            except IgnoreFieldException:
+                continue
             method = getattr(self, 'transform_%s' % field_name, None)
             if callable(method):
                 value = method(obj, value)
@@ -383,6 +386,9 @@ class BaseSerializer(WritableField):
         Override default so that the serializer can be used as a nested field
         across relationships.
         """
+        if self.write_only:
+            raise IgnoreFieldException()
+
         if self.source == '*':
             return self.to_native(obj)
 
@@ -615,6 +621,7 @@ class ModelSerializerOptions(SerializerOptions):
         super(ModelSerializerOptions, self).__init__(meta)
         self.model = getattr(meta, 'model', None)
         self.read_only_fields = getattr(meta, 'read_only_fields', ())
+        self.write_only_fields = getattr(meta, 'write_only_fields', ())
 
 
 class ModelSerializer(Serializer):
@@ -754,17 +761,29 @@ class ModelSerializer(Serializer):
         # Add the `read_only` flag to any fields that have bee specified
         # in the `read_only_fields` option
         for field_name in self.opts.read_only_fields:
-            assert field_name not in self.base_fields.keys(), \
-                "field '%s' on serializer '%s' specified in " \
-                "`read_only_fields`, but also added " \
-                "as an explicit field.  Remove it from `read_only_fields`." % \
-                (field_name, self.__class__.__name__)
-            assert field_name in ret, \
-                "Non-existant field '%s' specified in `read_only_fields` " \
-                "on serializer '%s'." % \
-                (field_name, self.__class__.__name__)
+            assert field_name not in self.base_fields.keys(), (
+                "field '%s' on serializer '%s' specified in "
+                "`read_only_fields`, but also added "
+                "as an explicit field.  Remove it from `read_only_fields`." %
+                (field_name, self.__class__.__name__))
+            assert field_name in ret, (
+                "Non-existant field '%s' specified in `read_only_fields` "
+                "on serializer '%s'." %
+                (field_name, self.__class__.__name__))
             ret[field_name].read_only = True
 
+        for field_name in self.opts.write_only_fields:
+            assert field_name not in self.base_fields.keys(), (
+                "field '%s' on serializer '%s' specified in "
+                "`write_only_fields`, but also added "
+                "as an explicit field.  Remove it from `write_only_fields`." %
+                (field_name, self.__class__.__name__))
+            assert field_name in ret, (
+                "Non-existant field '%s' specified in `write_only_fields` "
+                "on serializer '%s'." %
+                (field_name, self.__class__.__name__))
+            ret[field_name].write_only = True            
+
         return ret
 
     def get_pk_field(self, model_field):
diff --git a/rest_framework/tests/test_write_only_fields.py b/rest_framework/tests/test_write_only_fields.py
new file mode 100644
index 00000000..aabb18d6
--- /dev/null
+++ b/rest_framework/tests/test_write_only_fields.py
@@ -0,0 +1,42 @@
+from django.db import models
+from django.test import TestCase
+from rest_framework import serializers
+
+
+class ExampleModel(models.Model):
+    email = models.EmailField(max_length=100)
+    password = models.CharField(max_length=100)
+
+
+class WriteOnlyFieldTests(TestCase):
+    def test_write_only_fields(self):
+        class ExampleSerializer(serializers.Serializer):
+            email = serializers.EmailField()
+            password = serializers.CharField(write_only=True)
+
+        data = {
+            'email': 'foo@example.com',
+            'password': '123'
+        }
+        serializer = ExampleSerializer(data=data)
+        self.assertTrue(serializer.is_valid())
+        self.assertEquals(serializer.object, data)
+        self.assertEquals(serializer.data, {'email': 'foo@example.com'})
+
+    def test_write_only_fields_meta(self):
+        class ExampleSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = ExampleModel
+                fields = ('email', 'password')
+                write_only_fields = ('password',)
+
+        data = {
+            'email': 'foo@example.com',
+            'password': '123'
+        }
+        serializer = ExampleSerializer(data=data)
+        self.assertTrue(serializer.is_valid())
+        self.assertTrue(isinstance(serializer.object, ExampleModel))
+        self.assertEquals(serializer.object.email, data['email'])
+        self.assertEquals(serializer.object.password, data['password'])
+        self.assertEquals(serializer.data, {'email': 'foo@example.com'})