added allow_none (#15)

Author: nxexox

docs/api-guid/fields.md

@@ -66,6 +66,26 @@ print(SourceFieldSerializer(instance=Model()).data)
 # {'new_field': 10}
 ```
 
+###`allow_none`
+
+If set to True, skips None in the data field.
+
+**Example:**
+```python
+from rest_framework import serializers
+
+class StandardSerializer(serializers.Serializer):
+    field = serializers.IntegerField()
+
+class AllowNoneSerializer(serializers.Serializer):
+    field = serializers.IntegerField(allow_none=True)
+
+print(StandardSerializer(instance={'field': None}).data)
+# Raise Validation Exception
+print(AllowNoneSerializer(instance={'field': None}).data)
+# {'field': None}
+```
+
 ---
 
 # Fields

docs/release-notes.md

@@ -8,6 +8,12 @@ Medium version numbers (0.x.0) may include API changes, in line with the [deprec
 
 Major version numbers (x.0.0) are reserved for substantial project milestones.
 
+### 0.3.9
+
+**Date:** [10th September 2019]
+
+* Added the argument [`allow_none`][AllowNoneFieldAttribute] to all Serializer Fields.
+
 ### 0.3.8
 
 **Date:** [22th August 2019]
@@ -159,6 +165,7 @@ class TwoSer(Ser):
 * Push to Open Source community.
 
 
+[AllowNoneFieldAttribute]: api-guid/fields#allow_none
 [SourceFieldAttribute]: api-guid/fields#source
 [BaseViews]: api-guid/views/views
 [ViewsMixins]: api-guid/views/mixins

rest_framework/__init__.py

@@ -8,7 +8,7 @@
          __/ |
         |___/
 """
-VERSION = (0, 3, 8)
+VERSION = (0, 3, 9)
 
 __title__ = 'Python-Rest-Framework'
 __author__ = 'Deys Timofey'

rest_framework/serializers/fields.py

@@ -19,6 +19,7 @@
 
 from rest_framework.exceptions import SkipError
 from rest_framework.serializers.exceptions import ValidationError
+from rest_framework.serializers.helpers import get_class_name
 from rest_framework.utils import html
 from rest_framework.serializers.validators import (
     RequiredValidator, MaxLengthValidator, MinLengthValidator, MaxValueValidator, MinValueValidator
@@ -72,7 +73,7 @@ class Field(object):
     default_validators = []  # Default validators for field.
 
     def __init__(self, required=True, default=None, label=None, validators=None,
-                 error_messages=None, source=None):
+                 error_messages=None, source=None, allow_none=None):
         """
         Base field.
 
@@ -82,11 +83,13 @@ def __init__(self, required=True, default=None, label=None, validators=None,
         :param list validators: Validators for field.
         :param dict error_messages: Dictionary with custom error description.
         :param str source: Source field_name, if field_name object other in serializer.
+        :param bool allow_none: Allow None value in field?
 
         """
         self.label = label
         self.default = default
         self.source = source
+        self.allow_none = allow_none
         self.required = bool(required) if self.default is None else False
         # Added validator for check on required field.
         self._src_validators = validators
@@ -104,7 +107,7 @@ def __deepcopy__(self, memo={}):
         return self.__class__(
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def bind(self, field_name, parent):
@@ -191,6 +194,20 @@ def to_internal_value(self, data):
         """
         raise NotImplementedError('`to_internal_value()` must be implemented.')
 
+    def _to_representation(self, value):
+        """
+        Transformation an object to a valid JSON object.
+
+        :param object value: The object to transformation.
+
+        :return: Transformed data.
+        :rtype: object
+
+        """
+        if value is None and self.allow_none:
+            return value
+        return self.to_representation(value)
+
     def to_representation(self, value):
         """
         Transformation an object to a valid JSON object.
@@ -257,6 +274,8 @@ def get_attribute(self, instance):
             # If there is a default value, then it.
             if self.default is not None:
                 return self.get_default()
+            if self.allow_none:
+                return None
             # If there is no default and the field is required, we swear.
             if self.required:
                 raise SkipError(self.error_messages['required'])
@@ -270,8 +289,8 @@ def get_attribute(self, instance):
                 'Original exception text was: {exc}.'.format(
                     exc_type=type(e).__name__,
                     field=self.field_name,
-                    serializer=self.parent.__name__,
-                    instance=instance.__class__.__name__,
+                    serializer=get_class_name(self.parent),
+                    instance=get_class_name(instance),
                     exc=e
                 )
             )
@@ -396,7 +415,7 @@ def __deepcopy__(self, memo={}):
             validators=self._src_validators, error_messages=self._src_messages,
             min_length=self.min_length, max_length=self.max_length,
             trim_whitespace=self.trim_whitespace, allow_blank=self.allow_blank,
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def run_validation(self, data=None):
@@ -490,7 +509,7 @@ def __deepcopy__(self, memo={}):
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
             min_value=self.min_value, max_value=self.max_value,
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def to_internal_value(self, data):
@@ -566,7 +585,7 @@ def __deepcopy__(self, memo={}):
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
             min_value=self.min_value, max_value=self.max_value,
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def to_internal_value(self, data):
@@ -826,7 +845,7 @@ def __deepcopy__(self, memo={}):
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
             child=self.child, min_length=self.min_length, max_length=self.max_length,
-            allow_empty=self.allow_empty, source=self.source
+            allow_empty=self.allow_empty, source=self.source, allow_none=self.allow_none
         )
 
     def to_internal_value(self, data):
@@ -862,7 +881,7 @@ def to_representation(self, value):
         :rtype: list
 
         """
-        return [self.child.to_representation(item) if item is not None else None for item in (value or [])]
+        return [self.child._to_representation(item) if item is not None else None for item in (value or [])]
 
 
 class DateField(Field):
@@ -897,7 +916,7 @@ def __deepcopy__(self, memo={}):
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
             format=getattr(self, 'format'), input_format=getattr(self, 'input_format'),
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def to_internal_value(self, data):
@@ -997,7 +1016,7 @@ def __deepcopy__(self, memo={}):
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
             format=getattr(self, 'format', None), input_format=getattr(self, 'input_format'),
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def to_internal_value(self, data):
@@ -1095,7 +1114,7 @@ def __deepcopy__(self, memo={}):
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
             format=getattr(self, 'format'), input_format=getattr(self, 'input_format'),
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def to_internal_value(self, data):
@@ -1227,7 +1246,7 @@ def __deepcopy__(self, memo={}):
         return self.__class__(
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
-            child=self.child, source=self.source
+            child=self.child, source=self.source, allow_none=self.allow_none
         )
 
     def to_internal_value(self, data):
@@ -1264,7 +1283,7 @@ def to_representation(self, value):
 
         """
         return {
-            six.text_type(key): self.child.to_representation(val) if val is not None else None
+            six.text_type(key): self.child._to_representation(val) if val is not None else None
             for key, val in six.iteritems(value)
         }
 
@@ -1313,7 +1332,7 @@ def __deepcopy__(self, memo={}):
             required=self.required, default=self.default, label=self.label,
             validators=self._src_validators, error_messages=self._src_messages,
             method_name_get=self.method_name_get, method_name_pop=self.method_name_pop,
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def bind(self, field_name, parent):

rest_framework/serializers/helpers.py

@@ -5,6 +5,21 @@
 from collections import OrderedDict, MutableMapping
 
 
+def get_class_name(obj):
+    """
+    Get class name attribute.
+
+    :param Any obj: Object for get class name.
+
+    :return: Class name
+    :rtype: str
+
+    """
+    if isinstance(obj, type):
+        return obj.__name__
+    return obj.__class__.__name__
+
+
 class BindingDict(MutableMapping):
     """
     This dict-like object is used to store fields on a serializer.

rest_framework/serializers/serializers.py

@@ -131,7 +131,7 @@ def __new__(cls, *args, **kwargs):
         return super(BaseSerializer, cls).__new__(cls)
 
     def __deepcopy__(self, memo={}):
-        return self.__class__(instance=self.instance, data=self.data, source=self.source)
+        return self.__class__(instance=self.instance, data=self.data, source=self.source, allow_none=self.allow_none)
 
     @classmethod
     def many_init(cls, *args, **kwargs):
@@ -178,6 +178,20 @@ def to_internal_value(self, data):
         """
         raise NotImplementedError('`.to_internal_value()` must be implemented.')
 
+    def _to_representation(self, instance):
+        """
+        Transformation an object to a valid JSON object.
+
+        :param object instance: The object to transformation.
+
+        :return: Transformed data.
+        :rtype: dict
+
+        """
+        if instance is None and self.allow_none:
+            return instance
+        return self.to_representation(instance)
+
     def to_representation(self, instance):
         """
         Transformation an object to a valid JSON object.
@@ -279,9 +293,9 @@ def data(self):
 
         if not hasattr(self, '_data'):
             if self.instance is not None and not getattr(self, '_errors', None):
-                self._data = self.to_representation(self.instance)
+                self._data = self._to_representation(self.instance)
             elif hasattr(self, '_validated_data') and not getattr(self, '_errors', None):
-                self._data = self.to_representation(self._validated_data)
+                self._data = self._to_representation(self._validated_data)
             else:
                 self._data = self.get_default()
         return self._data
@@ -332,7 +346,7 @@ def to_representation(self, instance):
                 attribute = instance
 
             # We try to turn it into a JSON valid format.
-            res[field_name] = field_val.to_representation(attribute)
+            res[field_name] = field_val._to_representation(attribute)
 
         # Return.
         return res
@@ -524,7 +538,7 @@ def __deepcopy__(self, memo={}):
         return self.__class__(
             instance=self.instance, data=self.data,
             child=self.child, allow_empty=self.allow_empty,
-            source=self.source
+            source=self.source, allow_none=self.allow_none
         )
 
     def to_internal_value(self, data):
@@ -585,7 +599,7 @@ def to_representation(self, instance):
         :rtype: list
 
         """
-        return [self.child.to_representation(item) for item in instance]
+        return [self.child._to_representation(item) for item in instance]
 
     def is_valid(self, raise_exception=False):
         """

rest_framework/serializers/validators.py

@@ -3,8 +3,11 @@
 
 """
 import re
-
 import six
+try:
+    from typing import Mapping
+except ImportError:
+    from collections import Mapping
 
 from rest_framework.serializers.exceptions import ValidationError
 
@@ -243,7 +246,11 @@ def __init__(self, choices, *args, **kwargs):
         except TypeError:
             raise ValueError('`choices=` must be iter or dict. Reality: `{}`.'.format(type(choices)))
         super().__init__(*args, **kwargs)
-        self.choices = choices
+        self._choices = choices
+
+    @property
+    def choices(self):
+        return self._choices.keys() if isinstance(self._choices, Mapping) else self._choices
 
     def __call__(self, value: object):
         """

tests/serializers_for_tests.py

@@ -111,3 +111,21 @@ class SourceFieldFromSerializer(Serializer):
 
     """
     source_field_serializer = SerializerSourceFields(source='source_field', required=True)
+
+
+class AllowNoneSerializer(Serializer):
+    """
+    Serializer for testing `allow_none` argument on field.
+
+    """
+    integer = IntegerField(allow_none=True, required=False)
+    char = CharField(allow_none=True, required=False, max_length=5)
+    bool = BooleanField(allow_none=True, required=False)
+
+
+class InheritAllowNoneSerializer(Serializer):
+    """
+    Serializer for testing `allow_none` argument on field.
+
+    """
+    inherit = AllowNoneSerializer(allow_none=True)