Added JSONField. Closes #3170.

docs/api-guide/fields.md

@@ -459,6 +459,14 @@ You can also use the declarative style, as with `ListField`. For example:
     class DocumentField(DictField):
         child = CharField()
 
+## JSONField
+
+A field class that validates that the incoming data structure consists of valid JSON primitives. In its alternate binary mode, it will represent and validate JSON encoded strings.
+
+**Signature**: `JSONField(binary)`
+
+- `binary` - If set to `True` then the field will output and validate a JSON encoded string, rather that a primitive data structure. Defaults to `False`.
+
 ---
 
 # Miscellaneous fields

rest_framework/compat.py

@@ -64,6 +64,13 @@ except ImportError:
     postgres_fields = None
 
 
+# JSONField is only supported from 1.9 onwards
+try:
+    from django.contrib.postgres.fields import JSONField
+except ImportError:
+    JSONField = None
+
+
 # django-filter is optional
 try:
     import django_filters

rest_framework/fields.py

@@ -5,6 +5,7 @@ import copy
 import datetime
 import decimal
 import inspect
+import json
 import re
 import uuid
 from collections import OrderedDict
@@ -1522,6 +1523,31 @@ class DictField(Field):
         ])
 
 
+class JSONField(Field):
+    default_error_messages = {
+        'invalid': _('Value must be valid JSON.')
+    }
+
+    def __init__(self, *args, **kwargs):
+        self.binary = kwargs.pop('binary', False)
+        super(JSONField, self).__init__(*args, **kwargs)
+
+    def to_internal_value(self, data):
+        try:
+            if self.binary:
+                return json.loads(data)
+            else:
+                json.dumps(data)
+        except (TypeError, ValueError):
+            self.fail('invalid')
+        return data
+
+    def to_representation(self, value):
+        if self.binary:
+            return json.dumps(value)
+        return value
+
+
 # Miscellaneous field types...
 
 class ReadOnlyField(Field):

rest_framework/serializers.py

@@ -21,6 +21,7 @@ from django.utils.functional import cached_property
 from django.utils.translation import ugettext_lazy as _
 
 from rest_framework.compat import DurationField as ModelDurationField
+from rest_framework.compat import JSONField as ModelJSONField
 from rest_framework.compat import postgres_fields, unicode_to_repr
 from rest_framework.utils import model_meta
 from rest_framework.utils.field_mapping import (
@@ -790,6 +791,8 @@ class ModelSerializer(Serializer):
     }
     if ModelDurationField is not None:
         serializer_field_mapping[ModelDurationField] = DurationField
+    if ModelJSONField is not None:
+        serializer_field_mapping[ModelJSONField] = JSONField
     serializer_related_field = PrimaryKeyRelatedField
     serializer_url_field = HyperlinkedIdentityField
     serializer_choice_field = ChoiceField

tests/test_fields.py

@@ -1525,6 +1525,62 @@ class TestUnvalidatedDictField(FieldValues):
     field = serializers.DictField()
 
 
+class TestJSONField(FieldValues):
+    """
+    Values for `JSONField`.
+    """
+    valid_inputs = [
+        ({
+            'a': 1,
+            'b': ['some', 'list', True, 1.23],
+            '3': None
+        }, {
+            'a': 1,
+            'b': ['some', 'list', True, 1.23],
+            '3': None
+        }),
+    ]
+    invalid_inputs = [
+        ({'a': set()}, ['Value must be valid JSON.']),
+    ]
+    outputs = [
+        ({
+            'a': 1,
+            'b': ['some', 'list', True, 1.23],
+            '3': 3
+        }, {
+            'a': 1,
+            'b': ['some', 'list', True, 1.23],
+            '3': 3
+        }),
+    ]
+    field = serializers.JSONField()
+
+
+class TestBinaryJSONField(FieldValues):
+    """
+    Values for `JSONField` with binary=True.
+    """
+    valid_inputs = [
+        ('{"a": 1, "3": null, "b": ["some", "list", true, 1.23]}', {
+            'a': 1,
+            'b': ['some', 'list', True, 1.23],
+            '3': None
+        }),
+    ]
+    invalid_inputs = [
+        ('{"a": "unterminated string}', ['Value must be valid JSON.']),
+    ]
+    outputs = [
+        ({
+            'a': 1,
+            'b': ['some', 'list', True, 1.23],
+            '3': None
+        }, '{"a": 1, "3": null, "b": ["some", "list", true, 1.23]}'),
+    ]
+    field = serializers.JSONField(binary=True)
+
+
 # Tests for FieldField.
 # ---------------------