Add better date / datetime validation (pull 2)

addition to #631 with update to master + timefield support

5 files changed, 403 insertions, 56 deletions

diff --git a/docs/api-guide/fields.md b/docs/api-guide/fields.md
index d7f9197f..abacc1b8 100644
--- a/docs/api-guide/fields.md
+++ b/docs/api-guide/fields.md
@@ -185,12 +185,20 @@ Corresponds to `django.forms.fields.RegexField`
 
 A date representation.
 
+Uses `DATE_INPUT_FORMATS` to validate date.
+
+Optionally takes `format` as parameter to replace the matching pattern.
+
 Corresponds to `django.db.models.fields.DateField`
 
 ## DateTimeField
 
 A date and time representation.
 
+Uses `DATETIME_INPUT_FORMATS` to validate date_time.
+
+Optionally takes `format` as parameter to replace the matching pattern.
+
 Corresponds to `django.db.models.fields.DateTimeField`
 
 When using `ModelSerializer` or `HyperlinkedModelSerializer`, note that any model fields with `auto_now=True` or `auto_now_add=True` will use serializer fields that are `read_only=True` by default.
@@ -207,6 +215,10 @@ If you want to override this behavior, you'll need to declare the `DateTimeField
 
 A time representation.
 
+Uses `TIME_INPUT_FORMATS` to validate time.
+
+Optionally takes `format` as parameter to replace the matching pattern.
+
 Corresponds to `django.db.models.fields.TimeField`
 
 ## IntegerField
diff --git a/docs/topics/release-notes.md b/docs/topics/release-notes.md
index 43499c9a..f60382ac 100644
--- a/docs/topics/release-notes.md
+++ b/docs/topics/release-notes.md
@@ -45,6 +45,9 @@ You can determine your currently installed version using `pip freeze`:
 * Request authentication is no longer lazily evaluated, instead authentication is always run, which results in more consistent, obvious behavior.  Eg. Supplying bad auth credentials will now always return an error response, even if no permissions are set on the view.
 * Bugfix for serializer data being uncacheable with pickle protocol 0.
 * Bugfixes for model field validation edge-cases.
+* Support `DATE_INPUT_FORMATS` for `DateField` validation
+* Support `DATETIME_INPUT_FORMATS` for `DateTimeField` validation
+* Support `TIME_INPUT_FORMATS` for `TimeField` validation
 
 ### 2.2.1
 
diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 86c3a837..2260c430 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -19,6 +19,7 @@ from rest_framework.compat import BytesIO
 from rest_framework.compat import six
 from rest_framework.compat import smart_text
 from rest_framework.compat import parse_time
+from rest_framework.utils.dates import get_readable_date_format
 
 
 def is_simple_callable(obj):
@@ -447,13 +448,14 @@ class DateField(WritableField):
     form_field_class = forms.DateField
 
     default_error_messages = {
-        'invalid': _("'%s' value has an invalid date format. It must be "
-                     "in YYYY-MM-DD format."),
-        'invalid_date': _("'%s' value has the correct format (YYYY-MM-DD) "
-                          "but it is an invalid date."),
+        'invalid': _(u"Date has wrong format. Use one of these formats instead: %s"),
     }
     empty = None
 
+    def __init__(self, *args, **kwargs):
+        self.format = kwargs.pop('format', settings.DATE_INPUT_FORMATS)
+        super(DateField, self).__init__(*args, **kwargs)
+
     def from_native(self, value):
         if value in validators.EMPTY_VALUES:
             return None
@@ -468,15 +470,16 @@ class DateField(WritableField):
         if isinstance(value, datetime.date):
             return value
 
-        try:
-            parsed = parse_date(value)
-            if parsed is not None:
-                return parsed
-        except (ValueError, TypeError):
-            msg = self.error_messages['invalid_date'] % value
-            raise ValidationError(msg)
+        for format in self.format:
+            try:
+                parsed = datetime.datetime.strptime(value, format)
+            except (ValueError, TypeError):
+                pass
+            else:
+                return parsed.date()
 
-        msg = self.error_messages['invalid'] % value
+        date_input_formats = '; '.join(self.format)
+        msg = self.error_messages['invalid'] % get_readable_date_format(date_input_formats)
         raise ValidationError(msg)
 
 
@@ -486,16 +489,14 @@ class DateTimeField(WritableField):
     form_field_class = forms.DateTimeField
 
     default_error_messages = {
-        'invalid': _("'%s' value has an invalid format. It must be in "
-                     "YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ] format."),
-        'invalid_date': _("'%s' value has the correct format "
-                          "(YYYY-MM-DD) but it is an invalid date."),
-        'invalid_datetime': _("'%s' value has the correct format "
-                              "(YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ]) "
-                              "but it is an invalid date/time."),
+        'invalid': _(u"Datetime has wrong format. Use one of these formats instead: %s"),
     }
     empty = None
 
+    def __init__(self, *args, **kwargs):
+        self.format = kwargs.pop('format', settings.DATETIME_INPUT_FORMATS)
+        super(DateTimeField, self).__init__(*args, **kwargs)
+
     def from_native(self, value):
         if value in validators.EMPTY_VALUES:
             return None
@@ -516,23 +517,16 @@ class DateTimeField(WritableField):
                 value = timezone.make_aware(value, default_timezone)
             return value
 
-        try:
-            parsed = parse_datetime(value)
-            if parsed is not None:
+        for format in self.format:
+            try:
+                parsed = datetime.datetime.strptime(value, format)
+            except (ValueError, TypeError):
+                pass
+            else:
                 return parsed
-        except (ValueError, TypeError):
-            msg = self.error_messages['invalid_datetime'] % value
-            raise ValidationError(msg)
 
-        try:
-            parsed = parse_date(value)
-            if parsed is not None:
-                return datetime.datetime(parsed.year, parsed.month, parsed.day)
-        except (ValueError, TypeError):
-            msg = self.error_messages['invalid_date'] % value
-            raise ValidationError(msg)
-
-        msg = self.error_messages['invalid'] % value
+        datetime_input_formats = '; '.join(self.format)
+        msg = self.error_messages['invalid'] % get_readable_date_format(datetime_input_formats)
         raise ValidationError(msg)
 
 
@@ -542,11 +536,14 @@ class TimeField(WritableField):
     form_field_class = forms.TimeField
 
     default_error_messages = {
-        'invalid': _("'%s' value has an invalid format. It must be a valid "
-                     "time in the HH:MM[:ss[.uuuuuu]] format."),
+        'invalid': _(u"Time has wrong format. Use one of these formats instead: %s"),
     }
     empty = None
 
+    def __init__(self, *args, **kwargs):
+        self.format = kwargs.pop('format', settings.TIME_INPUT_FORMATS)
+        super(TimeField, self).__init__(*args, **kwargs)
+
     def from_native(self, value):
         if value in validators.EMPTY_VALUES:
             return None
@@ -554,13 +551,17 @@ class TimeField(WritableField):
         if isinstance(value, datetime.time):
             return value
 
-        try:
-            parsed = parse_time(value)
-            assert parsed is not None
-            return parsed
-        except (ValueError, TypeError):
-            msg = self.error_messages['invalid'] % value
-            raise ValidationError(msg)
+        for format in self.format:
+            try:
+                parsed = datetime.datetime.strptime(value, format)
+            except (ValueError, TypeError):
+                pass
+            else:
+                return parsed.time()
+
+        time_input_formats = '; '.join(self.format)
+        msg = self.error_messages['invalid'] % get_readable_date_format(time_input_formats)
+        raise ValidationError(msg)
 
 
 class IntegerField(WritableField):
diff --git a/rest_framework/tests/fields.py b/rest_framework/tests/fields.py
index 840ed320..37517642 100644
--- a/rest_framework/tests/fields.py
+++ b/rest_framework/tests/fields.py
@@ -3,9 +3,13 @@ General serializer field tests.
 """
 from __future__ import unicode_literals
 import datetime
+
+import django
 from django.db import models
 from django.test import TestCase
 from django.core import validators
+from django.utils import unittest
+
 from rest_framework import serializers
 
 
@@ -18,6 +22,21 @@ class CharPrimaryKeyModel(models.Model):
     id = models.CharField(max_length=20, primary_key=True)
 
 
+class DateObject(object):
+    def __init__(self, date):
+        self.date = date
+
+
+class DateTimeObject(object):
+    def __init__(self, date_time):
+        self.date_time = date_time
+
+
+class TimeObject(object):
+    def __init__(self, time):
+        self.time = time
+
+
 class TimestampedModelSerializer(serializers.ModelSerializer):
     class Meta:
         model = TimestampedModel
@@ -28,6 +47,66 @@ class CharPrimaryKeyModelSerializer(serializers.ModelSerializer):
         model = CharPrimaryKeyModel
 
 
+class DateObjectSerializer(serializers.Serializer):
+    date = serializers.DateField()
+
+    def restore_object(self, attrs, instance=None):
+        if instance is not None:
+            instance.date = attrs['date']
+            return instance
+        return DateObject(**attrs)
+
+
+class DateObjectCustomFormatSerializer(serializers.Serializer):
+    date = serializers.DateField(format=("%Y", "%Y -- %m"))
+
+    def restore_object(self, attrs, instance=None):
+        if instance is not None:
+            instance.date = attrs['date']
+            return instance
+        return DateObject(**attrs)
+
+
+class DateTimeObjectSerializer(serializers.Serializer):
+    date_time = serializers.DateTimeField()
+
+    def restore_object(self, attrs, instance=None):
+        if instance is not None:
+            instance.date_time = attrs['date_time']
+            return instance
+        return DateTimeObject(**attrs)
+
+
+class DateTimeObjectCustomFormatSerializer(serializers.Serializer):
+    date_time = serializers.DateTimeField(format=("%Y", "%Y %H:%M"))
+
+    def restore_object(self, attrs, instance=None):
+        if instance is not None:
+            instance.date_time = attrs['date_time']
+            return instance
+        return DateTimeObject(**attrs)
+
+
+class TimeObjectSerializer(serializers.Serializer):
+    time = serializers.TimeField()
+
+    def restore_object(self, attrs, instance=None):
+        if instance is not None:
+            instance.time = attrs['time']
+            return instance
+        return TimeObject(**attrs)
+
+
+class TimeObjectCustomFormatSerializer(serializers.Serializer):
+    time = serializers.TimeField(format=("%H -- %M", "%H%M%S"))
+
+    def restore_object(self, attrs, instance=None):
+        if instance is not None:
+            instance.time = attrs['time']
+            return instance
+        return TimeObject(**attrs)
+
+
 class TimeFieldModel(models.Model):
     clock = models.TimeField()
 
@@ -59,37 +138,275 @@ class BasicFieldTests(TestCase):
         serializer = CharPrimaryKeyModelSerializer()
         self.assertEqual(serializer.fields['id'].read_only, False)
 
-    def test_TimeField_from_native(self):
+
+class DateFieldTest(TestCase):
+    def test_valid_default_date_input_formats(self):
+        serializer = DateObjectSerializer(data={'date': '1984-07-31'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': '07/31/1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': '07/31/84'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': 'Jul 31 1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': 'Jul 31, 1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': '31 Jul 1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': '31 Jul 1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': 'July 31 1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': 'July 31, 1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': '31 July 1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectSerializer(data={'date': '31 July, 1984'})
+        self.assertTrue(serializer.is_valid())
+
+    def test_valid_custom_date_input_formats(self):
+        serializer = DateObjectCustomFormatSerializer(data={'date': '1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateObjectCustomFormatSerializer(data={'date': '1984 -- 07'})
+        self.assertTrue(serializer.is_valid())
+
+    def test_wrong_default_date_input_format(self):
+        serializer = DateObjectSerializer(data={'date': 'something wrong'})
+        self.assertFalse(serializer.is_valid())
+        self.assertEquals(serializer.errors, {'date': [u'Date has wrong format. Use one of these formats instead: '
+                                                       u'YYYY-MM-DD; MM/DD/YYYY; MM/DD/YY; [Jan through Dec] DD YYYY; '
+                                                       u'[Jan through Dec] DD, YYYY; DD [Jan through Dec] YYYY; '
+                                                       u'DD [Jan through Dec], YYYY; [January through December] DD YYYY; '
+                                                       u'[January through December] DD, YYYY; DD [January through December] YYYY; '
+                                                       u'DD [January through December], YYYY']})
+
+    def test_wrong_custom_date_input_format(self):
+        serializer = DateObjectCustomFormatSerializer(data={'date': '07/31/1984'})
+        self.assertFalse(serializer.is_valid())
+        self.assertEquals(serializer.errors, {'date': [u'Date has wrong format. Use one of these formats instead: YYYY; YYYY -- MM']})
+
+    def test_from_native(self):
+        f = serializers.DateField()
+        result = f.from_native('1984-07-31')
+
+        self.assertEqual(datetime.date(1984, 7, 31), result)
+
+    def test_from_native_datetime_date(self):
+        """
+        Make sure from_native() accepts a datetime.date instance.
+        """
+        f = serializers.DateField()
+        result = f.from_native(datetime.date(1984, 7, 31))
+
+        self.assertEqual(result, datetime.date(1984, 7, 31))
+
+    def test_from_native_empty(self):
+        f = serializers.DateField()
+        result = f.from_native('')
+
+        self.assertEqual(result, None)
+
+    def test_from_native_invalid_date(self):
+        f = serializers.DateField()
+
+        try:
+            f.from_native('1984-42-31')
+        except validators.ValidationError as e:
+            self.assertEqual(e.messages, [u'Date has wrong format. Use one of these formats instead: '
+                                          u'YYYY-MM-DD; MM/DD/YYYY; MM/DD/YY; [Jan through Dec] DD YYYY; '
+                                          u'[Jan through Dec] DD, YYYY; DD [Jan through Dec] YYYY; '
+                                          u'DD [Jan through Dec], YYYY; [January through December] DD YYYY; '
+                                          u'[January through December] DD, YYYY; DD [January through December] YYYY; '
+                                          u'DD [January through December], YYYY'])
+        else:
+            self.fail("ValidationError was not properly raised")
+
+
+class DateTimeFieldTest(TestCase):
+    def test_valid_default_date_time_input_formats(self):
+        serializer = DateTimeObjectSerializer(data={'date_time': '1984-07-31 04:31:59'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '1984-07-31 04:31'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '1984-07-31'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '07/31/1984 04:31:59'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '07/31/1984 04:31'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '07/31/1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '07/31/84 04:31:59'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '07/31/84 04:31'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '07/31/84'})
+        self.assertTrue(serializer.is_valid())
+
+    @unittest.skipUnless(django.VERSION >= (1, 4), "django < 1.4 don't have microseconds in default settings")
+    def test_valid_default_date_time_input_formats_for_django_gte_1_4(self):
+        serializer = DateTimeObjectSerializer(data={'date_time': '1984-07-31 04:31:59.123456'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '07/31/1984 04:31:59.123456'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectSerializer(data={'date_time': '07/31/84 04:31:59.123456'})
+        self.assertTrue(serializer.is_valid())
+
+    def test_valid_custom_date_time_input_formats(self):
+        serializer = DateTimeObjectCustomFormatSerializer(data={'date_time': '1984'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = DateTimeObjectCustomFormatSerializer(data={'date_time': '1984 04:31'})
+        self.assertTrue(serializer.is_valid())
+
+    @unittest.skipUnless(django.VERSION >= (1, 4), "django < 1.4 don't have microseconds in default settings")
+    def test_wrong_default_date_time_input_format_for_django_gte_1_4(self):
+        serializer = DateTimeObjectSerializer(data={'date_time': 'something wrong'})
+        self.assertFalse(serializer.is_valid())
+        self.assertEquals(serializer.errors, {'date_time': [u'Datetime has wrong format. Use one of these formats instead: '
+                                                            u'YYYY-MM-DD HH:MM:SS; YYYY-MM-DD HH:MM:SS.uuuuuu; YYYY-MM-DD HH:MM; '
+                                                            u'YYYY-MM-DD; MM/DD/YYYY HH:MM:SS; MM/DD/YYYY HH:MM:SS.uuuuuu; '
+                                                            u'MM/DD/YYYY HH:MM; MM/DD/YYYY; MM/DD/YY HH:MM:SS; '
+                                                            u'MM/DD/YY HH:MM:SS.uuuuuu; MM/DD/YY HH:MM; MM/DD/YY']})
+
+    @unittest.skipUnless(django.VERSION < (1, 4), "django >= 1.4 have microseconds in default settings")
+    def test_wrong_default_date_time_input_format_for_django_lt_1_4(self):
+        serializer = DateTimeObjectSerializer(data={'date_time': 'something wrong'})
+        self.assertFalse(serializer.is_valid())
+        self.assertEquals(serializer.errors, {'date_time': [u'Datetime has wrong format. Use one of these formats instead:'
+                                                            u' YYYY-MM-DD HH:MM:SS; YYYY-MM-DD HH:MM; YYYY-MM-DD; '
+                                                            u'MM/DD/YYYY HH:MM:SS; MM/DD/YYYY HH:MM; MM/DD/YYYY; '
+                                                            u'MM/DD/YY HH:MM:SS; MM/DD/YY HH:MM; MM/DD/YY']})
+
+    def test_wrong_custom_date_time_input_format(self):
+        serializer = DateTimeObjectCustomFormatSerializer(data={'date_time': '07/31/84 04:31'})
+        self.assertFalse(serializer.is_valid())
+        self.assertEquals(serializer.errors, {'date_time': [u'Datetime has wrong format. Use one of these formats instead: YYYY; YYYY HH:MM']})
+
+    def test_from_native(self):
+        f = serializers.DateTimeField()
+        result = f.from_native('1984-07-31 04:31')
+
+        self.assertEqual(datetime.datetime(1984, 7, 31, 4, 31), result)
+
+    def test_from_native_datetime_datetime(self):
+        """
+        Make sure from_native() accepts a datetime.date instance.
+        """
+        f = serializers.DateTimeField()
+        result = f.from_native(datetime.datetime(1984, 7, 31))
+
+        self.assertEqual(result, datetime.datetime(1984, 7, 31))
+
+    def test_from_native_empty(self):
+        f = serializers.DateTimeField()
+        result = f.from_native('')
+
+        self.assertEqual(result, None)
+
+    @unittest.skipUnless(django.VERSION >= (1, 4), "django < 1.4 don't have microseconds in default settings")
+    def test_from_native_invalid_datetime(self):
+        f = serializers.DateTimeField()
+
+        try:
+            f.from_native('1984-42-31 04:31')
+        except validators.ValidationError as e:
+            self.assertEqual(e.messages, [u'Datetime has wrong format. Use one of these formats instead: '
+                                          u'YYYY-MM-DD HH:MM:SS; YYYY-MM-DD HH:MM:SS.uuuuuu; YYYY-MM-DD HH:MM; '
+                                          u'YYYY-MM-DD; MM/DD/YYYY HH:MM:SS; MM/DD/YYYY HH:MM:SS.uuuuuu; '
+                                          u'MM/DD/YYYY HH:MM; MM/DD/YYYY; MM/DD/YY HH:MM:SS; '
+                                          u'MM/DD/YY HH:MM:SS.uuuuuu; MM/DD/YY HH:MM; MM/DD/YY'])
+        else:
+            self.fail("ValidationError was not properly raised")
+
+    @unittest.skipUnless(django.VERSION < (1, 4), "django >= 1.4 have microseconds in default settings")
+    def test_from_native_invalid_datetime(self):
+        f = serializers.DateTimeField()
+
+        try:
+            f.from_native('1984-42-31 04:31')
+        except validators.ValidationError as e:
+            self.assertEqual(e.messages, [u'Datetime has wrong format. Use one of these formats instead:'
+                                          u' YYYY-MM-DD HH:MM:SS; YYYY-MM-DD HH:MM; YYYY-MM-DD; '
+                                          u'MM/DD/YYYY HH:MM:SS; MM/DD/YYYY HH:MM; MM/DD/YYYY; '
+                                          u'MM/DD/YY HH:MM:SS; MM/DD/YY HH:MM; MM/DD/YY'])
+        else:
+            self.fail("ValidationError was not properly raised")
+
+
+class TimeFieldTest(TestCase):
+    def test_valid_default_time_input_formats(self):
+        serializer = TimeObjectSerializer(data={'time': '04:31'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = TimeObjectSerializer(data={'time': '04:31:59'})
+        self.assertTrue(serializer.is_valid())
+
+    def test_valid_custom_time_input_formats(self):
+        serializer = TimeObjectCustomFormatSerializer(data={'time': '04 -- 31'})
+        self.assertTrue(serializer.is_valid())
+
+        serializer = TimeObjectCustomFormatSerializer(data={'time': '043159'})
+        self.assertTrue(serializer.is_valid())
+
+    def test_wrong_default_time_input_format(self):
+        serializer = TimeObjectSerializer(data={'time': 'something wrong'})
+        self.assertFalse(serializer.is_valid())
+        self.assertEquals(serializer.errors, {'time': [u'Time has wrong format. Use one of these formats instead: HH:MM:SS; HH:MM']})
+
+    def test_wrong_custom_time_input_format(self):
+        serializer = TimeObjectCustomFormatSerializer(data={'time': '04:31'})
+        self.assertFalse(serializer.is_valid())
+        self.assertEquals(serializer.errors, {'time': [u'Time has wrong format. Use one of these formats instead: HH -- MM; HHMMSS']})
+
+    def test_from_native(self):
         f = serializers.TimeField()
-        result = f.from_native('12:34:56.987654')
+        result = f.from_native('12:34:56')
 
-        self.assertEqual(datetime.time(12, 34, 56, 987654), result)
+        self.assertEqual(datetime.time(12, 34, 56), result)
 
-    def test_TimeField_from_native_datetime_time(self):
+    def test_from_native_datetime_time(self):
         """
         Make sure from_native() accepts a datetime.time instance.
         """
         f = serializers.TimeField()
         result = f.from_native(datetime.time(12, 34, 56))
+
         self.assertEqual(result, datetime.time(12, 34, 56))
 
-    def test_TimeField_from_native_empty(self):
+    def test_from_native_empty(self):
         f = serializers.TimeField()
         result = f.from_native('')
+
         self.assertEqual(result, None)
 
-    def test_TimeField_from_native_invalid_time(self):
+    def test_from_native_invalid_time(self):
         f = serializers.TimeField()
 
         try:
             f.from_native('12:69:12')
         except validators.ValidationError as e:
-            self.assertEqual(e.messages, ["'12:69:12' value has an invalid "
-                                          "format. It must be a valid time "
-                                          "in the HH:MM[:ss[.uuuuuu]] format."])
+            self.assertEqual(e.messages, ["Time has wrong format. Use one of these formats instead: HH:MM:SS; HH:MM"])
         else:
             self.fail("ValidationError was not properly raised")
-
-    def test_TimeFieldModelSerializer(self):
-        serializer = TimeFieldModelSerializer()
-        self.assertTrue(isinstance(serializer.fields['clock'], serializers.TimeField))
diff --git a/rest_framework/utils/dates.py b/rest_framework/utils/dates.py
new file mode 100644
index 00000000..f094f72d
--- /dev/null
+++ b/rest_framework/utils/dates.py
@@ -0,0 +1,14 @@
+def get_readable_date_format(date_format):
+    mapping = [("%Y", "YYYY"),
+               ("%y", "YY"),
+               ("%m", "MM"),
+               ("%b", "[Jan through Dec]"),
+               ("%B", "[January through December]"),
+               ("%d", "DD"),
+               ("%H", "HH"),
+               ("%M", "MM"),
+               ("%S", "SS"),
+               ("%f", "uuuuuu")]
+    for k, v in mapping:
+        date_format = date_format.replace(k, v)
+    return date_format
\ No newline at end of file