Fleshing out serializer fields

5 files changed, 872 insertions, 315 deletions

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 250c0579..043a44ed 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -1,8 +1,18 @@
+from django.conf import settings
 from django.core import validators
 from django.core.exceptions import ValidationError
+from django.utils import timezone
+from django.utils.dateparse import parse_date, parse_datetime, parse_time
 from django.utils.encoding import is_protected_type
-from rest_framework.utils import html
+from django.utils.translation import ugettext_lazy as _
+from rest_framework import ISO_8601
+from rest_framework.compat import smart_text
+from rest_framework.settings import api_settings
+from rest_framework.utils import html, representation, humanize_datetime
+import datetime
+import decimal
 import inspect
+import warnings
 
 
 class empty:
@@ -71,22 +81,22 @@ class SkipField(Exception):
     pass
 
 
+NOT_READ_ONLY_WRITE_ONLY = 'May not set both `read_only` and `write_only`'
+NOT_READ_ONLY_REQUIRED = 'May not set both `read_only` and `required`'
+NOT_READ_ONLY_DEFAULT = 'May not set both `read_only` and `default`'
+NOT_REQUIRED_DEFAULT = 'May not set both `required` and `default`'
+MISSING_ERROR_MESSAGE = (
+    'ValidationError raised by `{class_name}`, but error key `{key}` does '
+    'not exist in the `error_messages` dictionary.'
+)
+
+
 class Field(object):
     _creation_counter = 0
 
-    MESSAGES = {
-        'required': 'This field is required.'
+    default_error_messages = {
+        'required': _('This field is required.')
     }
-
-    _NOT_READ_ONLY_WRITE_ONLY = 'May not set both `read_only` and `write_only`'
-    _NOT_READ_ONLY_REQUIRED = 'May not set both `read_only` and `required`'
-    _NOT_READ_ONLY_DEFAULT = 'May not set both `read_only` and `default`'
-    _NOT_REQUIRED_DEFAULT = 'May not set both `required` and `default`'
-    _MISSING_ERROR_MESSAGE = (
-        'ValidationError raised by `{class_name}`, but error key `{key}` does '
-        'not exist in the `MESSAGES` dictionary.'
-    )
-
     default_validators = []
 
     def __init__(self, read_only=False, write_only=False,
@@ -100,10 +110,10 @@ class Field(object):
             required = default is empty and not read_only
 
         # Some combinations of keyword arguments do not make sense.
-        assert not (read_only and write_only), self._NOT_READ_ONLY_WRITE_ONLY
-        assert not (read_only and required), self._NOT_READ_ONLY_REQUIRED
-        assert not (read_only and default is not empty), self._NOT_READ_ONLY_DEFAULT
-        assert not (required and default is not empty), self._NOT_REQUIRED_DEFAULT
+        assert not (read_only and write_only), NOT_READ_ONLY_WRITE_ONLY
+        assert not (read_only and required), NOT_READ_ONLY_REQUIRED
+        assert not (read_only and default is not empty), NOT_READ_ONLY_DEFAULT
+        assert not (required and default is not empty), NOT_REQUIRED_DEFAULT
 
         self.read_only = read_only
         self.write_only = write_only
@@ -113,7 +123,14 @@ class Field(object):
         self.initial = initial
         self.label = label
         self.style = {} if style is None else style
-        self.validators = self.default_validators + validators
+        self.validators = validators or self.default_validators[:]
+
+        # Collect default error message from self and parent classes
+        messages = {}
+        for cls in reversed(self.__class__.__mro__):
+            messages.update(getattr(cls, 'default_error_messages', {}))
+        messages.update(error_messages or {})
+        self.error_messages = messages
 
     def bind(self, field_name, parent, root):
         """
@@ -186,12 +203,14 @@ class Field(object):
                 self.fail('required')
             return self.get_default()
 
-        self.run_validators(data)
-        return self.to_native(data)
+        value = self.to_native(data)
+        self.run_validators(value)
+        return value
 
     def run_validators(self, value):
         if value in validators.EMPTY_VALUES:
             return
+
         errors = []
         for validator in self.validators:
             try:
@@ -218,33 +237,32 @@ class Field(object):
         A helper method that simply raises a validation error.
         """
         try:
-            raise ValidationError(self.MESSAGES[key].format(**kwargs))
+            msg = self.error_messages[key]
         except KeyError:
             class_name = self.__class__.__name__
-            msg = self._MISSING_ERROR_MESSAGE.format(class_name=class_name, key=key)
+            msg = MISSING_ERROR_MESSAGE.format(class_name=class_name, key=key)
             raise AssertionError(msg)
+        raise ValidationError(msg.format(**kwargs))
 
     def __new__(cls, *args, **kwargs):
+        """
+        When a field is instantiated, we store the arguments that were used,
+        so that we can present a helpful representation of the object.
+        """
         instance = super(Field, cls).__new__(cls)
         instance._args = args
         instance._kwargs = kwargs
         return instance
 
     def __repr__(self):
-        arg_string = ', '.join([repr(val) for val in self._args])
-        kwarg_string = ', '.join([
-            '%s=%s' % (key, repr(val)) for key, val in self._kwargs.items()
-        ])
-        if arg_string and kwarg_string:
-            arg_string += ', '
-        class_name = self.__class__.__name__
-        return "%s(%s%s)" % (class_name, arg_string, kwarg_string)
+        return representation.field_repr(self)
 
 
+# Boolean types...
+
 class BooleanField(Field):
-    MESSAGES = {
-        'required': 'This field is required.',
-        'invalid_value': '`{input}` is not a valid boolean.'
+    default_error_messages = {
+        'invalid': _('`{input}` is not a valid boolean.')
     }
     TRUE_VALUES = {'t', 'T', 'true', 'True', 'TRUE', '1', 1, True}
     FALSE_VALUES = {'f', 'F', 'false', 'False', 'FALSE', '0', 0, 0.0, False}
@@ -261,13 +279,23 @@ class BooleanField(Field):
             return True
         elif data in self.FALSE_VALUES:
             return False
-        self.fail('invalid_value', input=data)
+        self.fail('invalid', input=data)
+
+    def to_primative(self, value):
+        if value is None:
+            return None
+        if value in self.TRUE_VALUES:
+            return True
+        elif value in self.FALSE_VALUES:
+            return False
+        return bool(value)
 
 
+# String types...
+
 class CharField(Field):
-    MESSAGES = {
-        'required': 'This field is required.',
-        'blank': 'This field may not be blank.'
+    default_error_messages = {
+        'blank': _('This field may not be blank.')
     }
 
     def __init__(self, **kwargs):
@@ -281,19 +309,364 @@ class CharField(Field):
             self.fail('blank')
         return str(data)
 
+    def to_primative(self, value):
+        if value is None:
+            return None
+        return str(value)
 
-class ChoiceField(Field):
-    MESSAGES = {
-        'required': 'This field is required.',
-        'invalid_choice': '`{input}` is not a valid choice.'
+
+class EmailField(CharField):
+    default_error_messages = {
+        'invalid': _('Enter a valid email address.')
+    }
+    default_validators = [validators.validate_email]
+
+    def to_native(self, data):
+        ret = super(EmailField, self).to_native(data)
+        if ret is None:
+            return None
+        return ret.strip()
+
+    def to_primative(self, value):
+        ret = super(EmailField, self).to_primative(value)
+        if ret is None:
+            return None
+        return ret.strip()
+
+
+class RegexField(CharField):
+    def __init__(self, regex, **kwargs):
+        kwargs['validators'] = (
+            [validators.RegexValidator(regex)] +
+            kwargs.get('validators', [])
+        )
+        super(RegexField, self).__init__(**kwargs)
+
+
+class SlugField(CharField):
+    default_error_messages = {
+        'invalid': _("Enter a valid 'slug' consisting of letters, numbers, underscores or hyphens.")
+    }
+    default_validators = [validators.validate_slug]
+
+
+class URLField(CharField):
+    default_error_messages = {
+        'invalid': _("Enter a valid URL.")
+    }
+    default_validators = [validators.URLValidator()]
+
+
+# Number types...
+
+class IntegerField(Field):
+    default_error_messages = {
+        'invalid': _('A valid integer is required.')
+    }
+
+    def __init__(self, **kwargs):
+        max_value = kwargs.pop('max_value', None)
+        min_value = kwargs.pop('min_value', None)
+        super(IntegerField, self).__init__(**kwargs)
+        if max_value is not None:
+            self.validators.append(validators.MaxValueValidator(max_value))
+        if min_value is not None:
+            self.validators.append(validators.MinValueValidator(min_value))
+        print self.__class__.__name__, self.validators
+
+    def to_native(self, data):
+        try:
+            data = int(str(data))
+        except (ValueError, TypeError):
+            self.fail('invalid')
+        return data
+
+    def to_primative(self, value):
+        if value is None:
+            return None
+        return int(value)
+
+
+class FloatField(Field):
+    default_error_messages = {
+        'invalid': _("'%s' value must be a float."),
     }
-    coerce_to_type = str
 
     def __init__(self, **kwargs):
-        choices = kwargs.pop('choices')
+        max_value = kwargs.pop('max_value', None)
+        min_value = kwargs.pop('min_value', None)
+        super(FloatField, self).__init__(**kwargs)
+        if max_value is not None:
+            self.validators.append(validators.MaxValueValidator(max_value))
+        if min_value is not None:
+            self.validators.append(validators.MinValueValidator(min_value))
+
+    def to_primative(self, value):
+        if value is None:
+            return None
+        try:
+            return float(value)
+        except (TypeError, ValueError):
+            self.fail('invalid', value=value)
+
+    def to_native(self, value):
+        if value is None:
+            return None
+        return float(value)
+
+
+class DecimalField(Field):
+    default_error_messages = {
+        'invalid': _('Enter a number.'),
+        'max_value': _('Ensure this value is less than or equal to {max_value}.'),
+        'min_value': _('Ensure this value is greater than or equal to {min_value}.'),
+        'max_digits': _('Ensure that there are no more than {max_digits} digits in total.'),
+        'max_decimal_places': _('Ensure that there are no more than {max_decimal_places} decimal places.'),
+        'max_whole_digits': _('Ensure that there are no more than {max_whole_digits} digits before the decimal point.')
+    }
+
+    def __init__(self, max_value=None, min_value=None, max_digits=None, decimal_places=None, **kwargs):
+        self.max_value, self.min_value = max_value, min_value
+        self.max_digits, self.max_decimal_places = max_digits, decimal_places
+        super(DecimalField, self).__init__(**kwargs)
+        if max_value is not None:
+            self.validators.append(validators.MaxValueValidator(max_value))
+        if min_value is not None:
+            self.validators.append(validators.MinValueValidator(min_value))
+
+    def from_native(self, value):
+        """
+        Validates that the input is a decimal number. Returns a Decimal
+        instance. Returns None for empty values. Ensures that there are no more
+        than max_digits in the number, and no more than decimal_places digits
+        after the decimal point.
+        """
+        if value in validators.EMPTY_VALUES:
+            return None
+
+        value = smart_text(value).strip()
+        try:
+            value = decimal.Decimal(value)
+        except decimal.DecimalException:
+            self.fail('invalid')
+
+        # Check for NaN. It is the only value that isn't equal to itself,
+        # so we can use this to identify NaN values.
+        if value != value:
+            self.fail('invalid')
+
+        # Check for infinity and negative infinity.
+        if value in (decimal.Decimal('Inf'), decimal.Decimal('-Inf')):
+            self.fail('invalid')
+
+        sign, digittuple, exponent = value.as_tuple()
+        decimals = abs(exponent)
+        # digittuple doesn't include any leading zeros.
+        digits = len(digittuple)
+        if decimals > digits:
+            # We have leading zeros up to or past the decimal point.  Count
+            # everything past the decimal point as a digit.  We do not count
+            # 0 before the decimal point as a digit since that would mean
+            # we would not allow max_digits = decimal_places.
+            digits = decimals
+        whole_digits = digits - decimals
+
+        if self.max_digits is not None and digits > self.max_digits:
+            self.fail('max_digits', max_digits=self.max_digits)
+        if self.decimal_places is not None and decimals > self.decimal_places:
+            self.fail('max_decimal_places', max_decimal_places=self.max_decimal_places)
+        if self.max_digits is not None and self.decimal_places is not None and whole_digits > (self.max_digits - self.decimal_places):
+            self.fail('max_whole_digits', max_while_digits=self.max_digits - self.decimal_places)
+
+        return value
+
+
+# Date & time fields...
+
+class DateField(Field):
+    default_error_messages = {
+        'invalid': _("Date has wrong format. Use one of these formats instead: %s"),
+    }
+    input_formats = api_settings.DATE_INPUT_FORMATS
+    format = api_settings.DATE_FORMAT
+
+    def __init__(self, input_formats=None, format=None, *args, **kwargs):
+        self.input_formats = input_formats if input_formats is not None else self.input_formats
+        self.format = format if format is not None else self.format
+        super(DateField, self).__init__(*args, **kwargs)
+
+    def from_native(self, value):
+        if value in validators.EMPTY_VALUES:
+            return None
+
+        if isinstance(value, datetime.datetime):
+            if timezone and settings.USE_TZ and timezone.is_aware(value):
+                # Convert aware datetimes to the default time zone
+                # before casting them to dates (#17742).
+                default_timezone = timezone.get_default_timezone()
+                value = timezone.make_naive(value, default_timezone)
+            return value.date()
+        if isinstance(value, datetime.date):
+            return value
+
+        for format in self.input_formats:
+            if format.lower() == ISO_8601:
+                try:
+                    parsed = parse_date(value)
+                except (ValueError, TypeError):
+                    pass
+                else:
+                    if parsed is not None:
+                        return parsed
+            else:
+                try:
+                    parsed = datetime.datetime.strptime(value, format)
+                except (ValueError, TypeError):
+                    pass
+                else:
+                    return parsed.date()
+
+        humanized_format = humanize_datetime.date_formats(self.input_formats)
+        msg = self.error_messages['invalid'] % humanized_format
+        raise ValidationError(msg)
+
+    def to_primative(self, value):
+        if value is None or self.format is None:
+            return value
+
+        if isinstance(value, datetime.datetime):
+            value = value.date()
+
+        if self.format.lower() == ISO_8601:
+            return value.isoformat()
+        return value.strftime(self.format)
+
+
+class DateTimeField(Field):
+    default_error_messages = {
+        'invalid': _("Datetime has wrong format. Use one of these formats instead: %s"),
+    }
+    input_formats = api_settings.DATETIME_INPUT_FORMATS
+    format = api_settings.DATETIME_FORMAT
+
+    def __init__(self, input_formats=None, format=None, *args, **kwargs):
+        self.input_formats = input_formats if input_formats is not None else self.input_formats
+        self.format = format if format is not None else self.format
+        super(DateTimeField, self).__init__(*args, **kwargs)
+
+    def from_native(self, value):
+        if value in validators.EMPTY_VALUES:
+            return None
+
+        if isinstance(value, datetime.datetime):
+            return value
+        if isinstance(value, datetime.date):
+            value = datetime.datetime(value.year, value.month, value.day)
+            if settings.USE_TZ:
+                # For backwards compatibility, interpret naive datetimes in
+                # local time. This won't work during DST change, but we can't
+                # do much about it, so we let the exceptions percolate up the
+                # call stack.
+                warnings.warn("DateTimeField received a naive datetime (%s)"
+                              " while time zone support is active." % value,
+                              RuntimeWarning)
+                default_timezone = timezone.get_default_timezone()
+                value = timezone.make_aware(value, default_timezone)
+            return value
+
+        for format in self.input_formats:
+            if format.lower() == ISO_8601:
+                try:
+                    parsed = parse_datetime(value)
+                except (ValueError, TypeError):
+                    pass
+                else:
+                    if parsed is not None:
+                        return parsed
+            else:
+                try:
+                    parsed = datetime.datetime.strptime(value, format)
+                except (ValueError, TypeError):
+                    pass
+                else:
+                    return parsed
+
+        humanized_format = humanize_datetime.datetime_formats(self.input_formats)
+        msg = self.error_messages['invalid'] % humanized_format
+        raise ValidationError(msg)
+
+    def to_primative(self, value):
+        if value is None or self.format is None:
+            return value
+
+        if self.format.lower() == ISO_8601:
+            ret = value.isoformat()
+            if ret.endswith('+00:00'):
+                ret = ret[:-6] + 'Z'
+            return ret
+        return value.strftime(self.format)
 
-        assert choices, '`choices` argument is required and may not be empty'
 
+class TimeField(Field):
+    default_error_messages = {
+        'invalid': _("Time has wrong format. Use one of these formats instead: %s"),
+    }
+    input_formats = api_settings.TIME_INPUT_FORMATS
+    format = api_settings.TIME_FORMAT
+
+    def __init__(self, input_formats=None, format=None, *args, **kwargs):
+        self.input_formats = input_formats if input_formats is not None else self.input_formats
+        self.format = format if format is not None else self.format
+        super(TimeField, self).__init__(*args, **kwargs)
+
+    def from_native(self, value):
+        if value in validators.EMPTY_VALUES:
+            return None
+
+        if isinstance(value, datetime.time):
+            return value
+
+        for format in self.input_formats:
+            if format.lower() == ISO_8601:
+                try:
+                    parsed = parse_time(value)
+                except (ValueError, TypeError):
+                    pass
+                else:
+                    if parsed is not None:
+                        return parsed
+            else:
+                try:
+                    parsed = datetime.datetime.strptime(value, format)
+                except (ValueError, TypeError):
+                    pass
+                else:
+                    return parsed.time()
+
+        humanized_format = humanize_datetime.time_formats(self.input_formats)
+        msg = self.error_messages['invalid'] % humanized_format
+        raise ValidationError(msg)
+
+    def to_primative(self, value):
+        if value is None or self.format is None:
+            return value
+
+        if isinstance(value, datetime.datetime):
+            value = value.time()
+
+        if self.format.lower() == ISO_8601:
+            return value.isoformat()
+        return value.strftime(self.format)
+
+
+# Choice types...
+
+class ChoiceField(Field):
+    default_error_messages = {
+        'invalid_choice': _('`{input}` is not a valid choice.')
+    }
+
+    def __init__(self, choices, **kwargs):
         # Allow either single or paired choices style:
         # choices = [1, 2, 3]
         # choices = [(1, 'First'), (2, 'Second'), (3, 'Third')]
@@ -321,12 +694,14 @@ class ChoiceField(Field):
         except KeyError:
             self.fail('invalid_choice', input=data)
 
+    def to_primative(self, value):
+        return value
+
 
 class MultipleChoiceField(ChoiceField):
-    MESSAGES = {
-        'required': 'This field is required.',
-        'invalid_choice': '`{input}` is not a valid choice.',
-        'not_a_list': 'Expected a list of items but got type `{input_type}`'
+    default_error_messages = {
+        'invalid_choice': _('`{input}` is not a valid choice.'),
+        'not_a_list': _('Expected a list of items but got type `{input_type}`')
     }
 
     def to_native(self, data):
@@ -337,72 +712,42 @@ class MultipleChoiceField(ChoiceField):
             for item in data
         ])
 
-
-class IntegerField(Field):
-    MESSAGES = {
-        'required': 'This field is required.',
-        'invalid_integer': 'A valid integer is required.'
-    }
-
-    def __init__(self, **kwargs):
-        max_value = kwargs.pop('max_value', None)
-        min_value = kwargs.pop('min_value', None)
-        super(IntegerField, self).__init__(**kwargs)
-        if max_value is not None:
-            self.validators.append(validators.MaxValueValidator(max_value))
-        if min_value is not None:
-            self.validators.append(validators.MinValueValidator(min_value))
-
-    def to_native(self, data):
-        try:
-            data = int(str(data))
-        except (ValueError, TypeError):
-            self.fail('invalid_integer')
-        return data
-
     def to_primative(self, value):
-        if value is None:
-            return None
-        return int(value)
+        return value
 
 
-class EmailField(CharField):
+# File types...
+
+class FileField(Field):
     pass  # TODO
 
 
-class URLField(CharField):
+class ImageField(Field):
     pass  # TODO
 
 
-class RegexField(CharField):
-    def __init__(self, **kwargs):
-        self.regex = kwargs.pop('regex')
-        super(CharField, self).__init__(**kwargs)
-
+# Advanced field types...
 
-class DateField(CharField):
-    def __init__(self, **kwargs):
-        self.input_formats = kwargs.pop('input_formats', None)
-        super(DateField, self).__init__(**kwargs)
+class ReadOnlyField(Field):
+    """
+    A read-only field that simply returns the field value.
 
+    If the field is a method with no parameters, the method will be called
+    and it's return value used as the representation.
 
-class TimeField(CharField):
-    def __init__(self, **kwargs):
-        self.input_formats = kwargs.pop('input_formats', None)
-        super(TimeField, self).__init__(**kwargs)
+    For example, the following would call `get_expiry_date()` on the object:
 
+    class ExampleSerializer(self):
+        expiry_date = ReadOnlyField(source='get_expiry_date')
+    """
 
-class DateTimeField(CharField):
     def __init__(self, **kwargs):
-        self.input_formats = kwargs.pop('input_formats', None)
-        super(DateTimeField, self).__init__(**kwargs)
-
-
-class FileField(Field):
-    pass  # TODO
+        kwargs['read_only'] = True
+        super(ReadOnlyField, self).__init__(**kwargs)
 
+    def to_native(self, data):
+        raise NotImplemented('.to_native() not supported.')
 
-class ReadOnlyField(Field):
     def to_primative(self, value):
         if is_simple_callable(value):
             return value()
@@ -410,11 +755,28 @@ class ReadOnlyField(Field):
 
 
 class MethodField(Field):
+    """
+    A read-only field that get its representation from calling a method on the
+    parent serializer class. The method called will be of the form
+    "get_{field_name}", and should take a single argument, which is the
+    object being serialized.
+
+    For example:
+
+    class ExampleSerializer(self):
+        extra_info = MethodField()
+
+        def get_extra_info(self, obj):
+            return ...  # Calculate some data to return.
+    """
     def __init__(self, **kwargs):
         kwargs['source'] = '*'
         kwargs['read_only'] = True
         super(MethodField, self).__init__(**kwargs)
 
+    def to_native(self, data):
+        raise NotImplemented('.to_native() not supported.')
+
     def to_primative(self, value):
         attr = 'get_{field_name}'.format(field_name=self.field_name)
         method = getattr(self.parent, attr)
@@ -424,35 +786,14 @@ class MethodField(Field):
 class ModelField(Field):
     """
     A generic field that can be used against an arbitrary model field.
-    """
-    def __init__(self, *args, **kwargs):
-        try:
-            self.model_field = kwargs.pop('model_field')
-        except KeyError:
-            raise ValueError("ModelField requires 'model_field' kwarg")
-
-        self.min_length = kwargs.pop('min_length',
-                                     getattr(self.model_field, 'min_length', None))
-        self.max_length = kwargs.pop('max_length',
-                                     getattr(self.model_field, 'max_length', None))
-        self.min_value = kwargs.pop('min_value',
-                                    getattr(self.model_field, 'min_value', None))
-        self.max_value = kwargs.pop('max_value',
-                                    getattr(self.model_field, 'max_value', None))
-
-        super(ModelField, self).__init__(*args, **kwargs)
-
-        if self.min_length is not None:
-            self.validators.append(validators.MinLengthValidator(self.min_length))
-        if self.max_length is not None:
-            self.validators.append(validators.MaxLengthValidator(self.max_length))
-        if self.min_value is not None:
-            self.validators.append(validators.MinValueValidator(self.min_value))
-        if self.max_value is not None:
-            self.validators.append(validators.MaxValueValidator(self.max_value))
 
-    def get_attribute(self, instance):
-        return get_attribute(instance, self.source_attrs[:-1])
+    This is used by `ModelSerializer` when dealing with custom model fields,
+    that do not have a serializer field to be mapped to.
+    """
+    def __init__(self, model_field, **kwargs):
+        self.model_field = model_field
+        kwargs['source'] = '*'
+        super(ModelField, self).__init__(**kwargs)
 
     def to_native(self, data):
         rel = getattr(self.model_field, 'rel', None)
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 93226d32..8ca28387 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -10,15 +10,15 @@ python primitives.
 2. The process of marshalling between python primitives and request and
 response content is handled by parsers and renderers.
 """
+from django.core import validators
 from django.core.exceptions import ValidationError
 from django.db import models
 from django.utils import six
 from collections import namedtuple, OrderedDict
 from rest_framework.fields import empty, set_value, Field, SkipField
 from rest_framework.settings import api_settings
-from rest_framework.utils import html
+from rest_framework.utils import html, modelinfo, representation
 import copy
-import inspect
 
 # Note: We do the following so that users of the framework can use this style:
 #
@@ -146,12 +146,10 @@ class SerializerMetaclass(type):
 class Serializer(BaseSerializer):
 
     def __new__(cls, *args, **kwargs):
-        many = kwargs.pop('many', False)
-        if many:
-            class DynamicListSerializer(ListSerializer):
-                child = cls()
-            return DynamicListSerializer(*args, **kwargs)
-        return super(Serializer, cls).__new__(cls)
+        if kwargs.pop('many', False):
+            kwargs['child'] = cls()
+            return ListSerializer(*args, **kwargs)
+        return super(Serializer, cls).__new__(cls, *args, **kwargs)
 
     def __init__(self, *args, **kwargs):
         self.context = kwargs.pop('context', {})
@@ -248,6 +246,9 @@ class Serializer(BaseSerializer):
             error = errors.get(field.field_name)
             yield FieldResult(field, value, error)
 
+    def __repr__(self):
+        return representation.serializer_repr(self, indent=1)
+
 
 class ListSerializer(BaseSerializer):
     child = None
@@ -299,26 +300,8 @@ class ListSerializer(BaseSerializer):
         self.instance = self.create(self.validated_data)
         return self.instance
 
-
-def _resolve_model(obj):
-    """
-    Resolve supplied `obj` to a Django model class.
-
-    `obj` must be a Django model class itself, or a string
-    representation of one.  Useful in situtations like GH #1225 where
-    Django may not have resolved a string-based reference to a model in
-    another model's foreign key definition.
-
-    String representations should have the format:
-        'appname.ModelName'
-    """
-    if isinstance(obj, six.string_types) and len(obj.split('.')) == 2:
-        app_name, model_name = obj.split('.')
-        return models.get_model(app_name, model_name)
-    elif inspect.isclass(obj) and issubclass(obj, models.Model):
-        return obj
-    else:
-        raise ValueError("{0} is not a Django model".format(obj))
+    def __repr__(self):
+        return representation.list_repr(self, indent=1)
 
 
 class ModelSerializerOptions(object):
@@ -334,24 +317,25 @@ class ModelSerializerOptions(object):
 class ModelSerializer(Serializer):
     field_mapping = {
         models.AutoField: IntegerField,
-        # models.FloatField: FloatField,
+        models.BigIntegerField: IntegerField,
+        models.BooleanField: BooleanField,
+        models.CharField: CharField,
+        models.CommaSeparatedIntegerField: CharField,
+        models.DateField: DateField,
+        models.DateTimeField: DateTimeField,
+        models.DecimalField: DecimalField,
+        models.EmailField: EmailField,
+        models.FileField: FileField,
+        models.FloatField: FloatField,
         models.IntegerField: IntegerField,
+        models.NullBooleanField: BooleanField,
         models.PositiveIntegerField: IntegerField,
-        models.SmallIntegerField: IntegerField,
         models.PositiveSmallIntegerField: IntegerField,
-        models.DateTimeField: DateTimeField,
-        models.DateField: DateField,
+        models.SlugField: SlugField,
+        models.SmallIntegerField: IntegerField,
+        models.TextField: CharField,
         models.TimeField: TimeField,
-        # models.DecimalField: DecimalField,
-        models.EmailField: EmailField,
-        models.CharField: CharField,
         models.URLField: URLField,
-        # models.SlugField: SlugField,
-        models.TextField: CharField,
-        models.CommaSeparatedIntegerField: CharField,
-        models.BooleanField: BooleanField,
-        models.NullBooleanField: BooleanField,
-        models.FileField: FileField,
         # models.ImageField: ImageField,
     }
 
@@ -392,85 +376,31 @@ class ModelSerializer(Serializer):
         """
         Return all the fields that should be serialized for the model.
         """
-        cls = self.opts.model
-        opts = cls._meta.concrete_model._meta
+        info = modelinfo.get_field_info(self.opts.model)
         ret = OrderedDict()
-        nested = bool(self.opts.depth)
 
-        # Deal with adding the primary key field
-        pk_field = opts.pk
-        while pk_field.rel and pk_field.rel.parent_link:
-            # If model is a child via multitable inheritance, use parent's pk
-            pk_field = pk_field.rel.to._meta.pk
-
-        serializer_pk_field = self.get_pk_field(pk_field)
+        serializer_pk_field = self.get_pk_field(info.pk)
         if serializer_pk_field:
-            ret[pk_field.name] = serializer_pk_field
-
-        # Deal with forward relationships
-        forward_rels = [field for field in opts.fields if field.serialize]
-        forward_rels += [field for field in opts.many_to_many if field.serialize]
-
-        for model_field in forward_rels:
-            has_through_model = False
-
-            if model_field.rel:
-                to_many = isinstance(model_field,
-                                     models.fields.related.ManyToManyField)
-                related_model = _resolve_model(model_field.rel.to)
-
-                if to_many and not model_field.rel.through._meta.auto_created:
-                    has_through_model = True
+            ret[info.pk.name] = serializer_pk_field
 
-            if model_field.rel and nested:
-                field = self.get_nested_field(model_field, related_model, to_many)
-            elif model_field.rel:
-                field = self.get_related_field(model_field, related_model, to_many)
-            else:
-                field = self.get_field(model_field)
-
-            if field:
-                if has_through_model:
-                    field.read_only = True
+        # Regular fields
+        for field_name, field in info.fields.items():
+            ret[field_name] = self.get_field(field)
 
-                ret[model_field.name] = field
-
-        # Deal with reverse relationships
-        if not self.opts.fields:
-            reverse_rels = []
-        else:
-            # Reverse relationships are only included if they are explicitly
-            # present in the `fields` option on the serializer
-            reverse_rels = opts.get_all_related_objects()
-            reverse_rels += opts.get_all_related_many_to_many_objects()
-
-        for relation in reverse_rels:
-            accessor_name = relation.get_accessor_name()
-            if not self.opts.fields or accessor_name not in self.opts.fields:
-                continue
-            related_model = relation.model
-            to_many = relation.field.rel.multiple
-            has_through_model = False
-            is_m2m = isinstance(relation.field,
-                                models.fields.related.ManyToManyField)
-
-            if (
-                is_m2m and
-                hasattr(relation.field.rel, 'through') and
-                not relation.field.rel.through._meta.auto_created
-            ):
-                has_through_model = True
-
-            if nested:
-                field = self.get_nested_field(None, related_model, to_many)
+        # Forward relations
+        for field_name, relation_info in info.forward_relations.items():
+            if self.opts.depth:
+                ret[field_name] = self.get_nested_field(*relation_info)
             else:
-                field = self.get_related_field(None, related_model, to_many)
+                ret[field_name] = self.get_related_field(*relation_info)
 
-            if field:
-                if has_through_model:
-                    field.read_only = True
-
-                ret[accessor_name] = field
+        # Reverse relations
+        for accessor_name, relation_info in info.reverse_relations.items():
+            if accessor_name in self.opts.fields:
+                if self.opts.depth:
+                    ret[field_name] = self.get_nested_field(*relation_info)
+                else:
+                    ret[field_name] = self.get_related_field(*relation_info)
 
         return ret
 
@@ -480,7 +410,7 @@ class ModelSerializer(Serializer):
         """
         return self.get_field(model_field)
 
-    def get_nested_field(self, model_field, related_model, to_many):
+    def get_nested_field(self, model_field, related_model, to_many, has_through_model):
         """
         Creates a default instance of a nested relational field.
 
@@ -491,59 +421,148 @@ class ModelSerializer(Serializer):
                 model = related_model
                 depth = self.opts.depth - 1
 
-        return NestedModelSerializer(many=to_many)
+        kwargs = {'read_only': True}
+        if to_many:
+            kwargs['many'] = True
+        return NestedModelSerializer(**kwargs)
 
-    def get_related_field(self, model_field, related_model, to_many):
+    def get_related_field(self, model_field, related_model, to_many, has_through_model):
         """
         Creates a default instance of a flat relational field.
 
         Note that model_field will be `None` for reverse relationships.
         """
-        # TODO: filter queryset using:
-        # .using(db).complex_filter(self.rel.limit_choices_to)
+        kwargs = {
+            'queryset': related_model._default_manager,
+        }
 
-        kwargs = {}
-        #     'queryset': related_model._default_manager,
-        #     'many': to_many
-        # }
+        if to_many:
+            kwargs['many'] = True
+
+        if has_through_model:
+            kwargs['read_only'] = True
+            kwargs.pop('queryset', None)
 
         if model_field:
-            kwargs['required'] = not(model_field.null or model_field.blank)
+            if model_field.null or model_field.blank:
+                kwargs['required'] = False
             #  if model_field.help_text is not None:
             #      kwargs['help_text'] = model_field.help_text
             if model_field.verbose_name is not None:
                 kwargs['label'] = model_field.verbose_name
             if not model_field.editable:
                 kwargs['read_only'] = True
-            if model_field.verbose_name is not None:
-                kwargs['label'] = model_field.verbose_name
+                kwargs.pop('queryset', None)
 
-        return IntegerField(**kwargs)
-        # TODO: return PrimaryKeyRelatedField(**kwargs)
+        return PrimaryKeyRelatedField(**kwargs)
 
     def get_field(self, model_field):
         """
         Creates a default instance of a basic non-relational field.
         """
         kwargs = {}
+        validator_kwarg = model_field.validators
 
         if model_field.null or model_field.blank:
             kwargs['required'] = False
 
+        if model_field.verbose_name is not None:
+            kwargs['label'] = model_field.verbose_name
+
         if isinstance(model_field, models.AutoField) or not model_field.editable:
             kwargs['read_only'] = True
+            # Read only implies that the field is not required.
+            # We have a cleaner repr on the instance if we don't set it.
+            kwargs.pop('required', None)
 
         if model_field.has_default():
             kwargs['default'] = model_field.get_default()
-
-        if issubclass(model_field.__class__, models.TextField):
-            kwargs['widget'] = widgets.Textarea
-
-        if model_field.verbose_name is not None:
-            kwargs['label'] = model_field.verbose_name
-
-        if model_field.validators is not None:
-            kwargs['validators'] = model_field.validators
+            # Having a default implies that the field is not required.
+            # We have a cleaner repr on the instance if we don't set it.
+            kwargs.pop('required', None)
+
+        # Ensure that max_length is passed explicitly as a keyword arg,
+        # rather than as a validator.
+        max_length = getattr(model_field, 'max_length', None)
+        if max_length is not None:
+            kwargs['max_length'] = max_length
+            validator_kwarg = [
+                validator for validator in validator_kwarg
+                if not isinstance(validator, validators.MaxLengthValidator)
+            ]
+
+        # Ensure that min_length is passed explicitly as a keyword arg,
+        # rather than as a validator.
+        min_length = getattr(model_field, 'min_length', None)
+        if min_length is not None:
+            kwargs['min_length'] = min_length
+            validator_kwarg = [
+                validator for validator in validator_kwarg
+                if not isinstance(validator, validators.MinLengthValidator)
+            ]
+
+        # Ensure that max_value is passed explicitly as a keyword arg,
+        # rather than as a validator.
+        max_value = next((
+            validator.limit_value for validator in validator_kwarg
+            if isinstance(validator, validators.MaxValueValidator)
+        ), None)
+        if max_value is not None:
+            kwargs['max_value'] = max_value
+            validator_kwarg = [
+                validator for validator in validator_kwarg
+                if not isinstance(validator, validators.MaxValueValidator)
+            ]
+
+        # Ensure that max_value is passed explicitly as a keyword arg,
+        # rather than as a validator.
+        min_value = next((
+            validator.limit_value for validator in validator_kwarg
+            if isinstance(validator, validators.MinValueValidator)
+        ), None)
+        if min_value is not None:
+            kwargs['min_value'] = min_value
+            validator_kwarg = [
+                validator for validator in validator_kwarg
+                if not isinstance(validator, validators.MinValueValidator)
+            ]
+
+        # URLField does not need to include the URLValidator argument,
+        # as it is explicitly added in.
+        if isinstance(model_field, models.URLField):
+            validator_kwarg = [
+                validator for validator in validator_kwarg
+                if not isinstance(validator, validators.URLValidator)
+            ]
+
+        # EmailField does not need to include the validate_email argument,
+        # as it is explicitly added in.
+        if isinstance(model_field, models.EmailField):
+            validator_kwarg = [
+                validator for validator in validator_kwarg
+                if validator is not validators.validate_email
+            ]
+
+        # SlugField do not need to include the 'validate_slug' argument,
+        if isinstance(model_field, models.SlugField):
+            validator_kwarg = [
+                validator for validator in validator_kwarg
+                if validator is not validators.validate_slug
+            ]
+
+        max_digits = getattr(model_field, 'max_digits', None)
+        if max_digits is not None:
+            kwargs['max_digits'] = max_digits
+
+        decimal_places = getattr(model_field, 'decimal_places', None)
+        if decimal_places is not None:
+            kwargs['decimal_places'] = decimal_places
+
+        if validator_kwarg:
+            kwargs['validators'] = validator_kwarg
+
+        # if issubclass(model_field.__class__, models.TextField):
+        #     kwargs['widget'] = widgets.Textarea
 
         # if model_field.help_text is not None:
         #     kwargs['help_text'] = model_field.help_text
@@ -555,31 +574,10 @@ class ModelSerializer(Serializer):
                 kwargs['empty'] = None
             return ChoiceField(**kwargs)
 
-        # put this below the ChoiceField because min_value isn't a valid initializer
-        if issubclass(model_field.__class__, models.PositiveIntegerField) or \
-                issubclass(model_field.__class__, models.PositiveSmallIntegerField):
-            kwargs['min_value'] = 0
-
         if model_field.null and \
                 issubclass(model_field.__class__, (models.CharField, models.TextField)):
             kwargs['allow_none'] = True
 
-        # attribute_dict = {
-        #     models.CharField: ['max_length'],
-        #     models.CommaSeparatedIntegerField: ['max_length'],
-        #     models.DecimalField: ['max_digits', 'decimal_places'],
-        #     models.EmailField: ['max_length'],
-        #     models.FileField: ['max_length'],
-        #     models.ImageField: ['max_length'],
-        #     models.SlugField: ['max_length'],
-        #     models.URLField: ['max_length'],
-        # }
-
-        # if model_field.__class__ in attribute_dict:
-        #     attributes = attribute_dict[model_field.__class__]
-        #     for attribute in attributes:
-        #         kwargs.update({attribute: getattr(model_field, attribute)})
-
         try:
             return self.field_mapping[model_field.__class__](**kwargs)
         except KeyError:
@@ -594,28 +592,21 @@ class HyperlinkedModelSerializerOptions(ModelSerializerOptions):
         super(HyperlinkedModelSerializerOptions, self).__init__(meta)
         self.view_name = getattr(meta, 'view_name', None)
         self.lookup_field = getattr(meta, 'lookup_field', None)
-        self.url_field_name = getattr(meta, 'url_field_name', api_settings.URL_FIELD_NAME)
 
 
 class HyperlinkedModelSerializer(ModelSerializer):
     _options_class = HyperlinkedModelSerializerOptions
-    _default_view_name = '%(model_name)s-detail'
-    _hyperlink_field_class = HyperlinkedRelatedField
-    _hyperlink_identify_field_class = HyperlinkedIdentityField
 
     def get_default_fields(self):
         fields = super(HyperlinkedModelSerializer, self).get_default_fields()
 
         if self.opts.view_name is None:
-            self.opts.view_name = self._get_default_view_name(self.opts.model)
+            self.opts.view_name = self.get_default_view_name(self.opts.model)
 
-        if self.opts.url_field_name not in fields:
-            url_field = self._hyperlink_identify_field_class(
-                view_name=self.opts.view_name,
-                lookup_field=self.opts.lookup_field
-            )
+        url_field_name = api_settings.URL_FIELD_NAME
+        if url_field_name not in fields:
             ret = fields.__class__()
-            ret[self.opts.url_field_name] = url_field
+            ret[url_field_name] = self.get_url_field()
             ret.update(fields)
             fields = ret
 
@@ -625,39 +616,48 @@ class HyperlinkedModelSerializer(ModelSerializer):
         if self.opts.fields and model_field.name in self.opts.fields:
             return self.get_field(model_field)
 
-    def get_related_field(self, model_field, related_model, to_many):
+    def get_url_field(self):
+        kwargs = {
+            'view_name': self.get_default_view_name(self.opts.model)
+        }
+        if self.opts.lookup_field:
+            kwargs['lookup_field'] = self.opts.lookup_field
+        return HyperlinkedIdentityField(**kwargs)
+
+    def get_related_field(self, model_field, related_model, to_many, has_through_model):
         """
         Creates a default instance of a flat relational field.
         """
-        # TODO: filter queryset using:
-        # .using(db).complex_filter(self.rel.limit_choices_to)
-        # kwargs = {
-        #     'queryset': related_model._default_manager,
-        #     'view_name': self._get_default_view_name(related_model),
-        #     'many': to_many
-        # }
-        kwargs = {}
+        kwargs = {
+            'queryset': related_model._default_manager,
+            'view_name': self.get_default_view_name(related_model),
+        }
+
+        if to_many:
+            kwargs['many'] = True
+
+        if has_through_model:
+            kwargs['read_only'] = True
+            kwargs.pop('queryset', None)
 
         if model_field:
-            kwargs['required'] = not(model_field.null or model_field.blank)
+            if model_field.null or model_field.blank:
+                kwargs['required'] = False
             # if model_field.help_text is not None:
             #     kwargs['help_text'] = model_field.help_text
             if model_field.verbose_name is not None:
                 kwargs['label'] = model_field.verbose_name
+            if not model_field.editable:
+                kwargs['read_only'] = True
+                kwargs.pop('queryset', None)
 
-        return IntegerField(**kwargs)
-        # if self.opts.lookup_field:
-        #     kwargs['lookup_field'] = self.opts.lookup_field
-
-        # return self._hyperlink_field_class(**kwargs)
+        return HyperlinkedRelatedField(**kwargs)
 
-    def _get_default_view_name(self, model):
+    def get_default_view_name(self, model):
         """
-        Return the view name to use if 'view_name' is not specified in 'Meta'
+        Return the view name to use for related models.
         """
-        model_meta = model._meta
-        format_kwargs = {
-            'app_label': model_meta.app_label,
-            'model_name': model_meta.object_name.lower()
+        return '%(model_name)s-detail' % {
+            'app_label': model._meta.app_label,
+            'model_name': model._meta.object_name.lower()
         }
-        return self._default_view_name % format_kwargs
diff --git a/rest_framework/utils/humanize_datetime.py b/rest_framework/utils/humanize_datetime.py
new file mode 100644
index 00000000..649f2abc
--- /dev/null
+++ b/rest_framework/utils/humanize_datetime.py
@@ -0,0 +1,47 @@
+"""
+Helper functions that convert strftime formats into more readable representations.
+"""
+from rest_framework import ISO_8601
+
+
+def datetime_formats(formats):
+    format = ', '.join(formats).replace(
+        ISO_8601,
+        'YYYY-MM-DDThh:mm[:ss[.uuuuuu]][+HH:MM|-HH:MM|Z]'
+    )
+    return humanize_strptime(format)
+
+
+def date_formats(formats):
+    format = ', '.join(formats).replace(ISO_8601, 'YYYY[-MM[-DD]]')
+    return humanize_strptime(format)
+
+
+def time_formats(formats):
+    format = ', '.join(formats).replace(ISO_8601, 'hh:mm[:ss[.uuuuuu]]')
+    return humanize_strptime(format)
+
+
+def humanize_strptime(format_string):
+    # Note that we're missing some of the locale specific mappings that
+    # don't really make sense.
+    mapping = {
+        "%Y": "YYYY",
+        "%y": "YY",
+        "%m": "MM",
+        "%b": "[Jan-Dec]",
+        "%B": "[January-December]",
+        "%d": "DD",
+        "%H": "hh",
+        "%I": "hh",  # Requires '%p' to differentiate from '%H'.
+        "%M": "mm",
+        "%S": "ss",
+        "%f": "uuuuuu",
+        "%a": "[Mon-Sun]",
+        "%A": "[Monday-Sunday]",
+        "%p": "[AM|PM]",
+        "%z": "[+HHMM|-HHMM]"
+    }
+    for key, val in mapping.items():
+        format_string = format_string.replace(key, val)
+    return format_string
diff --git a/rest_framework/utils/modelinfo.py b/rest_framework/utils/modelinfo.py
new file mode 100644
index 00000000..c0513886
--- /dev/null
+++ b/rest_framework/utils/modelinfo.py
@@ -0,0 +1,97 @@
+"""
+Helper functions for returning the field information that is associated
+with a model class.
+"""
+from collections import namedtuple, OrderedDict
+from django.db import models
+from django.utils import six
+import inspect
+
+FieldInfo = namedtuple('FieldResult', ['pk', 'fields', 'forward_relations', 'reverse_relations'])
+RelationInfo = namedtuple('RelationInfo', ['field', 'related', 'to_many', 'has_through_model'])
+
+
+def _resolve_model(obj):
+    """
+    Resolve supplied `obj` to a Django model class.
+
+    `obj` must be a Django model class itself, or a string
+    representation of one.  Useful in situtations like GH #1225 where
+    Django may not have resolved a string-based reference to a model in
+    another model's foreign key definition.
+
+    String representations should have the format:
+        'appname.ModelName'
+    """
+    if isinstance(obj, six.string_types) and len(obj.split('.')) == 2:
+        app_name, model_name = obj.split('.')
+        return models.get_model(app_name, model_name)
+    elif inspect.isclass(obj) and issubclass(obj, models.Model):
+        return obj
+    raise ValueError("{0} is not a Django model".format(obj))
+
+
+def get_field_info(model):
+    """
+    Given a model class, returns a `FieldInfo` instance containing metadata
+    about the various field types on the model.
+    """
+    opts = model._meta.concrete_model._meta
+
+    # Deal with the primary key.
+    pk = opts.pk
+    while pk.rel and pk.rel.parent_link:
+        # If model is a child via multitable inheritance, use parent's pk.
+        pk = pk.rel.to._meta.pk
+
+    # Deal with regular fields.
+    fields = OrderedDict()
+    for field in [field for field in opts.fields if field.serialize and not field.rel]:
+        fields[field.name] = field
+
+    # Deal with forward relationships.
+    forward_relations = OrderedDict()
+    for field in [field for field in opts.fields if field.serialize and field.rel]:
+        forward_relations[field.name] = RelationInfo(
+            field=field,
+            related=_resolve_model(field.rel.to),
+            to_many=False,
+            has_through_model=False
+        )
+
+    # Deal with forward many-to-many relationships.
+    for field in [field for field in opts.many_to_many if field.serialize]:
+        forward_relations[field.name] = RelationInfo(
+            field=field,
+            related=_resolve_model(field.rel.to),
+            to_many=True,
+            has_through_model=(
+                not field.rel.through._meta.auto_created
+            )
+        )
+
+    # Deal with reverse relationships.
+    reverse_relations = OrderedDict()
+    for relation in opts.get_all_related_objects():
+        accessor_name = relation.get_accessor_name()
+        reverse_relations[accessor_name] = RelationInfo(
+            field=None,
+            related=relation.model,
+            to_many=relation.field.rel.multiple,
+            has_through_model=False
+        )
+
+    # Deal with reverse many-to-many relationships.
+    for relation in opts.get_all_related_many_to_many_objects():
+        accessor_name = relation.get_accessor_name()
+        reverse_relations[accessor_name] = RelationInfo(
+            field=None,
+            related=relation.model,
+            to_many=True,
+            has_through_model=(
+                hasattr(relation.field.rel, 'through') and
+                not relation.field.rel.through._meta.auto_created
+            )
+        )
+
+    return FieldInfo(pk, fields, forward_relations, reverse_relations)
diff --git a/rest_framework/utils/representation.py b/rest_framework/utils/representation.py
new file mode 100644
index 00000000..1de21597
--- /dev/null
+++ b/rest_framework/utils/representation.py
@@ -0,0 +1,72 @@
+"""
+Helper functions for creating user-friendly representations
+of serializer classes and serializer fields.
+"""
+import re
+
+
+def smart_repr(value):
+    value = repr(value)
+
+    # Representations like u'help text'
+    # should simply be presented as 'help text'
+    if value.startswith("u'") and value.endswith("'"):
+        return value[1:]
+
+    # Representations like
+    # <django.core.validators.RegexValidator object at 0x1047af050>
+    # Should be presented as
+    # <django.core.validators.RegexValidator object>
+    value = re.sub(' at 0x[0-9a-f]{8,10}>', '>', value)
+
+    return value
+
+
+def field_repr(field, force_many=False):
+    kwargs = field._kwargs
+    if force_many:
+        kwargs = kwargs.copy()
+        kwargs['many'] = True
+        kwargs.pop('child', None)
+
+    arg_string = ', '.join([smart_repr(val) for val in field._args])
+    kwarg_string = ', '.join([
+        '%s=%s' % (key, smart_repr(val))
+        for key, val in sorted(kwargs.items())
+    ])
+    if arg_string and kwarg_string:
+        arg_string += ', '
+
+    if force_many:
+        class_name = force_many.__class__.__name__
+    else:
+        class_name = field.__class__.__name__
+
+    return "%s(%s%s)" % (class_name, arg_string, kwarg_string)
+
+
+def serializer_repr(serializer, indent, force_many=None):
+    ret = field_repr(serializer, force_many) + ':'
+    indent_str = '    ' * indent
+
+    if force_many:
+        fields = force_many.fields
+    else:
+        fields = serializer.fields
+
+    for field_name, field in fields.items():
+        ret += '\n' + indent_str + field_name + ' = '
+        if hasattr(field, 'fields'):
+            ret += serializer_repr(field, indent + 1)
+        elif hasattr(field, 'child'):
+            ret += list_repr(field, indent + 1)
+        else:
+            ret += field_repr(field)
+    return ret
+
+
+def list_repr(serializer, indent):
+    child = serializer.child
+    if hasattr(child, 'fields'):
+        return serializer_repr(serializer, indent, force_many=child)
+    return field_repr(serializer)