Add DurationField

Author: ticosax

docs/api-guide/fields.md

@@ -302,6 +302,18 @@ Corresponds to `django.db.models.fields.TimeField`
 
 Format strings may either be [Python strftime formats][strftime] which explicitly specify the format, or the special string `'iso-8601'`, which indicates that [ISO 8601][iso8601] style times should be used. (eg `'12:34:56.000000'`)
 
+## DurationField
+
+A Duration representation.
+Corresponds to `django.db.models.fields.Duration`
+
+The `validated_data` for these fields will contain a `datetime.timedelta` instance.
+The representation is a string following this format `'[DD] [HH:[MM:]]ss[.uuuuuu]'`.
+
+**Note:** This field is only available with Django versions >= 1.8.
+
+**Signature:** `DurationField()`
+
 ---
 
 # Choice selection fields

rest_framework/compat.py

@@ -258,3 +258,11 @@ def apply_markdown(text):
     SHORT_SEPARATORS = (b',', b':')
     LONG_SEPARATORS = (b', ', b': ')
     INDENT_SEPARATORS = (b',', b': ')
+
+
+if django.VERSION >= (1, 8):
+    from django.db.models import DurationField
+    from django.utils.dateparse import parse_duration
+    from django.utils.duration import duration_string
+else:
+    DurationField = duration_string = parse_duration = None

rest_framework/fields.py

@@ -12,7 +12,7 @@
 from rest_framework.compat import (
     EmailValidator, MinValueValidator, MaxValueValidator,
     MinLengthValidator, MaxLengthValidator, URLValidator, OrderedDict,
-    unicode_repr, unicode_to_repr
+    unicode_repr, unicode_to_repr, parse_duration, duration_string,
 )
 from rest_framework.exceptions import ValidationError
 from rest_framework.settings import api_settings
@@ -1003,6 +1003,29 @@ def to_representation(self, value):
         return value.strftime(self.format)
 
 
+class DurationField(Field):
+    default_error_messages = {
+        'invalid': _('Duration has wrong format. Use one of these formats instead: {format}.'),
+    }
+
+    def __init__(self, *args, **kwargs):
+        if parse_duration is None:
+            raise NotImplementedError(
+                'DurationField not supported for django versions prior to 1.8')
+        return super(DurationField, self).__init__(*args, **kwargs)
+
+    def to_internal_value(self, value):
+        if isinstance(value, datetime.timedelta):
+            return value
+        parsed = parse_duration(value)
+        if parsed is not None:
+            return parsed
+        self.fail('invalid', format='[DD] [HH:[MM:]]ss[.uuuuuu]')
+
+    def to_representation(self, value):
+        return duration_string(value)
+
+
 # Choice types...
 
 class ChoiceField(Field):

rest_framework/serializers.py

@@ -15,7 +15,11 @@
 from django.db.models.fields import FieldDoesNotExist, Field as DjangoModelField
 from django.db.models import query
 from django.utils.translation import ugettext_lazy as _
-from rest_framework.compat import postgres_fields, unicode_to_repr
+from rest_framework.compat import (
+    postgres_fields,
+    unicode_to_repr,
+    DurationField as ModelDurationField,
+)
 from rest_framework.utils import model_meta
 from rest_framework.utils.field_mapping import (
     get_url_kwargs, get_field_kwargs,
@@ -731,6 +735,8 @@ class ModelSerializer(Serializer):
         models.TimeField: TimeField,
         models.URLField: URLField,
     }
+    if ModelDurationField is not None:
+        serializer_field_mapping[ModelDurationField] = DurationField
     serializer_related_field = PrimaryKeyRelatedField
     serializer_url_field = HyperlinkedIdentityField
     serializer_choice_field = ChoiceField

tests/test_fields.py

@@ -905,6 +905,28 @@ class TestNoOutputFormatTimeField(FieldValues):
     field = serializers.TimeField(format=None)
 
 
+@pytest.mark.skipif(django.VERSION < (1, 8),
+                    reason='DurationField is only available for django1.8+')
+class TestDurationField(FieldValues):
+    """
+    Valid and invalid values for `DurationField`.
+    """
+    valid_inputs = {
+        '13': datetime.timedelta(seconds=13),
+        '3 08:32:01.000123': datetime.timedelta(days=3, hours=8, minutes=32, seconds=1, microseconds=123),
+        '08:01': datetime.timedelta(minutes=8, seconds=1),
+        datetime.timedelta(days=3, hours=8, minutes=32, seconds=1, microseconds=123): datetime.timedelta(days=3, hours=8, minutes=32, seconds=1, microseconds=123),
+    }
+    invalid_inputs = {
+        'abc': ['Duration has wrong format. Use one of these formats instead: [DD] [HH:[MM:]]ss[.uuuuuu].'],
+        '3 08:32 01.123': ['Duration has wrong format. Use one of these formats instead: [DD] [HH:[MM:]]ss[.uuuuuu].'],
+    }
+    outputs = {
+        datetime.timedelta(days=3, hours=8, minutes=32, seconds=1, microseconds=123): '3 08:32:01.000123',
+    }
+    field = serializers.DurationField()
+
+
 # Choice types...
 
 class TestChoiceField(FieldValues):

tests/test_model_serializer.py

@@ -6,13 +6,15 @@
 an appropriate set of serializer fields for each case.
 """
 from __future__ import unicode_literals
+import django
 from django.core.exceptions import ImproperlyConfigured
 from django.core.validators import MaxValueValidator, MinValueValidator, MinLengthValidator
 from django.db import models
 from django.test import TestCase
 from django.utils import six
+import pytest
 from rest_framework import serializers
-from rest_framework.compat import unicode_repr
+from rest_framework.compat import unicode_repr, DurationField as ModelDurationField
 
 
 def dedent(blocktext):
@@ -284,6 +286,28 @@ class Meta:
         ChildSerializer().fields
 
 
+@pytest.mark.skipif(django.VERSION < (1, 8),
+                    reason='DurationField is only available for django1.8+')
+class TestDurationFieldMapping(TestCase):
+    def test_duration_field(self):
+        class DurationFieldModel(models.Model):
+            """
+            A model that defines DurationField.
+            """
+            duration_field = ModelDurationField()
+
+        class TestSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = DurationFieldModel
+
+        expected = dedent("""
+            TestSerializer():
+                id = IntegerField(label='ID', read_only=True)
+                duration_field = DurationField()
+        """)
+        self.assertEqual(unicode_repr(TestSerializer()), expected)
+
+
 # Tests for relational field mappings.
 # ------------------------------------