Merged soc2009/model-validation to trunk. Thanks, Honza!

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12098 bcc190cf-cafb-0310-a4f2-bffc1f526a37

3 files changed, 379 insertions, 76 deletions

diff --git a/django/db/models/base.py b/django/db/models/base.py
index 3464ae6712..935933ae0e 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -3,7 +3,8 @@ import sys
 import os
 from itertools import izip
 import django.db.models.manager     # Imported to register signal handler.
-from django.core.exceptions import ObjectDoesNotExist, MultipleObjectsReturned, FieldError
+from django.core.exceptions import ObjectDoesNotExist, MultipleObjectsReturned, FieldError, ValidationError, NON_FIELD_ERRORS
+from django.core import validators
 from django.db.models.fields import AutoField, FieldDoesNotExist
 from django.db.models.fields.related import OneToOneRel, ManyToOneRel, OneToOneField
 from django.db.models.query import delete_objects, Q
@@ -12,9 +13,11 @@ from django.db.models.options import Options
 from django.db import connections, transaction, DatabaseError, DEFAULT_DB_ALIAS
 from django.db.models import signals
 from django.db.models.loading import register_models, get_model
+from django.utils.translation import ugettext_lazy as _
 import django.utils.copycompat as copy
 from django.utils.functional import curry
 from django.utils.encoding import smart_str, force_unicode, smart_unicode
+from django.utils.text import get_text_list, capfirst
 from django.conf import settings
 
 class ModelBase(type):
@@ -639,6 +642,180 @@ class Model(object):
     def prepare_database_save(self, unused):
         return self.pk
 
+    def validate(self):
+        """
+        Hook for doing any extra model-wide validation after clean() has been
+        called on every field. Any ValidationError raised by this method will
+        not be associated with a particular field; it will have a special-case
+        association with the field defined by NON_FIELD_ERRORS.
+        """
+        self.validate_unique()
+
+    def validate_unique(self):
+        unique_checks, date_checks = self._get_unique_checks()
+
+        errors = self._perform_unique_checks(unique_checks)
+        date_errors = self._perform_date_checks(date_checks)
+
+        for k, v in date_errors.items():
+             errors.setdefault(k, []).extend(v)
+
+        if errors:
+            raise ValidationError(errors)
+
+    def _get_unique_checks(self):
+        from django.db.models.fields import FieldDoesNotExist, Field as ModelField
+
+        unique_checks = list(self._meta.unique_together)
+        # these are checks for the unique_for_<date/year/month>
+        date_checks = []
+
+        # Gather a list of checks for fields declared as unique and add them to
+        # the list of checks. Again, skip empty fields and any that did not validate.
+        for f in self._meta.fields:
+            name = f.name
+            if f.unique:
+                unique_checks.append((name,))
+            if f.unique_for_date:
+                date_checks.append(('date', name, f.unique_for_date))
+            if f.unique_for_year:
+                date_checks.append(('year', name, f.unique_for_year))
+            if f.unique_for_month:
+                date_checks.append(('month', name, f.unique_for_month))
+        return unique_checks, date_checks
+
+
+    def _perform_unique_checks(self, unique_checks):
+        errors = {}
+
+        for unique_check in unique_checks:
+            # Try to look up an existing object with the same values as this
+            # object's values for all the unique field.
+
+            lookup_kwargs = {}
+            for field_name in unique_check:
+                f = self._meta.get_field(field_name)
+                lookup_value = getattr(self, f.attname)
+                if f.null and lookup_value is None:
+                    # no value, skip the lookup
+                    continue
+                if f.primary_key and not getattr(self, '_adding', False):
+                    # no need to check for unique primary key when editting 
+                    continue
+                lookup_kwargs[str(field_name)] = lookup_value
+
+            # some fields were skipped, no reason to do the check
+            if len(unique_check) != len(lookup_kwargs.keys()):
+                continue
+
+            qs = self.__class__._default_manager.filter(**lookup_kwargs)
+
+            # Exclude the current object from the query if we are editing an
+            # instance (as opposed to creating a new one)
+            if not getattr(self, '_adding', False) and self.pk is not None:
+                qs = qs.exclude(pk=self.pk)
+
+            # This cute trick with extra/values is the most efficient way to
+            # tell if a particular query returns any results.
+            if qs.extra(select={'a': 1}).values('a').order_by():
+                if len(unique_check) == 1:
+                    key = unique_check[0]
+                else:
+                    key = NON_FIELD_ERRORS
+                errors.setdefault(key, []).append(self.unique_error_message(unique_check))
+
+        return errors
+
+    def _perform_date_checks(self, date_checks):
+        errors = {}
+        for lookup_type, field, unique_for in date_checks:
+            lookup_kwargs = {}
+            # there's a ticket to add a date lookup, we can remove this special
+            # case if that makes it's way in
+            date = getattr(self, unique_for)
+            if lookup_type == 'date':
+                lookup_kwargs['%s__day' % unique_for] = date.day
+                lookup_kwargs['%s__month' % unique_for] = date.month
+                lookup_kwargs['%s__year' % unique_for] = date.year
+            else:
+                lookup_kwargs['%s__%s' % (unique_for, lookup_type)] = getattr(date, lookup_type)
+            lookup_kwargs[field] = getattr(self, field)
+
+            qs = self.__class__._default_manager.filter(**lookup_kwargs)
+            # Exclude the current object from the query if we are editing an
+            # instance (as opposed to creating a new one)
+            if not getattr(self, '_adding', False) and self.pk is not None:
+                qs = qs.exclude(pk=self.pk)
+
+            # This cute trick with extra/values is the most efficient way to
+            # tell if a particular query returns any results.
+            if qs.extra(select={'a': 1}).values('a').order_by():
+                errors.setdefault(field, []).append(
+                    self.date_error_message(lookup_type, field, unique_for)
+                )
+        return errors
+
+    def date_error_message(self, lookup_type, field, unique_for):
+        opts = self._meta
+        return _(u"%(field_name)s must be unique for %(date_field)s %(lookup)s.") % {
+            'field_name': unicode(capfirst(opts.get_field(field).verbose_name)),
+            'date_field': unicode(capfirst(opts.get_field(unique_for).verbose_name)),
+            'lookup': lookup_type,
+        }
+
+    def unique_error_message(self, unique_check):
+        opts = self._meta
+        model_name = capfirst(opts.verbose_name)
+
+        # A unique field
+        if len(unique_check) == 1:
+            field_name = unique_check[0]
+            field_label = capfirst(opts.get_field(field_name).verbose_name)
+            # Insert the error into the error dict, very sneaky
+            return _(u"%(model_name)s with this %(field_label)s already exists.") %  {
+                'model_name': unicode(model_name),
+                'field_label': unicode(field_label)
+            }
+        # unique_together
+        else:
+            field_labels = map(lambda f: capfirst(opts.get_field(f).verbose_name), unique_check)
+            field_labels = get_text_list(field_labels, _('and'))
+            return _(u"%(model_name)s with this %(field_label)s already exists.") %  {
+                'model_name': unicode(model_name),
+                'field_label': unicode(field_labels)
+            }
+
+    def full_validate(self, exclude=[]):
+        """
+        Cleans all fields and raises ValidationError containing message_dict
+        of all validation errors if any occur.
+        """
+        errors = {}
+        for f in self._meta.fields:
+            if f.name in exclude:
+                continue
+            try:
+                setattr(self, f.attname, f.clean(getattr(self, f.attname), self))
+            except ValidationError, e:
+                errors[f.name] = e.messages
+
+        # Form.clean() is run even if other validation fails, so do the
+        # same with Model.validate() for consistency.
+        try:
+            self.validate()
+        except ValidationError, e:
+            if hasattr(e, 'message_dict'):
+                if errors:
+                    for k, v in e.message_dict.items():
+                        errors.set_default(k, []).extend(v)
+                else:
+                    errors = e.message_dict
+            else:
+                errors[NON_FIELD_ERRORS] = e.messages
+
+        if errors:
+            raise ValidationError(errors)
+
 
 ############################################
 # HELPER FUNCTIONS (CURRIED MODEL METHODS) #
diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index b70f320df3..25f44a4d1c 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -13,12 +13,12 @@ from django.db.models.query_utils import QueryWrapper
 from django.dispatch import dispatcher
 from django.conf import settings
 from django import forms
-from django.core import exceptions
+from django.core import exceptions, validators
 from django.utils.datastructures import DictWrapper
 from django.utils.functional import curry
 from django.utils.itercompat import tee
 from django.utils.text import capfirst
-from django.utils.translation import ugettext_lazy, ugettext as _
+from django.utils.translation import ugettext_lazy as _, ugettext
 from django.utils.encoding import smart_unicode, force_unicode, smart_str
 from django.utils import datetime_safe
 
@@ -60,6 +60,12 @@ class Field(object):
     # creates, creation_counter is used for all user-specified fields.
     creation_counter = 0
     auto_creation_counter = -1
+    default_validators = [] # Default set of validators
+    default_error_messages = {
+        'invalid_choice': _(u'Value %r is not a valid choice.'),
+        'null': _(u'This field cannot be null.'),
+        'blank': _(u'This field cannot be blank.'),
+    }
 
     # Generic field type description, usually overriden by subclasses
     def _description(self):
@@ -73,7 +79,8 @@ class Field(object):
             db_index=False, rel=None, default=NOT_PROVIDED, editable=True,
             serialize=True, unique_for_date=None, unique_for_month=None,
             unique_for_year=None, choices=None, help_text='', db_column=None,
-            db_tablespace=None, auto_created=False):
+            db_tablespace=None, auto_created=False, validators=[],
+            error_messages=None):
         self.name = name
         self.verbose_name = verbose_name
         self.primary_key = primary_key
@@ -106,6 +113,42 @@ class Field(object):
             self.creation_counter = Field.creation_counter
             Field.creation_counter += 1
 
+        self.validators = self.default_validators + validators
+
+        messages = {}
+        for c in reversed(self.__class__.__mro__):
+            messages.update(getattr(c, 'default_error_messages', {}))
+        messages.update(error_messages or {})
+        self.error_messages = messages
+
+    def __getstate__(self):
+        """
+        Pickling support.
+        """
+        from django.utils.functional import Promise
+        obj_dict = self.__dict__.copy()
+        items = []
+        translated_keys = []
+        for k, v in self.error_messages.items():
+            if isinstance(v, Promise):
+                args = getattr(v, '_proxy____args', None)
+                if args:
+                    translated_keys.append(k)
+                    v = args[0]
+            items.append((k,v))
+        obj_dict['_translated_keys'] = translated_keys
+        obj_dict['error_messages'] = dict(items)
+        return obj_dict
+
+    def __setstate__(self, obj_dict):
+        """
+        Unpickling support.
+        """
+        translated_keys = obj_dict.pop('_translated_keys')
+        self.__dict__.update(obj_dict)
+        for k in translated_keys:
+            self.error_messages[k] = _(self.error_messages[k])
+
     def __cmp__(self, other):
         # This is needed because bisect does not take a comparison function.
         return cmp(self.creation_counter, other.creation_counter)
@@ -127,6 +170,54 @@ class Field(object):
         """
         return value
 
+    def run_validators(self, value):
+        if value in validators.EMPTY_VALUES:
+            return
+
+        errors = []
+        for v in self.validators:
+            try:
+                v(value)
+            except exceptions.ValidationError, e:
+                if hasattr(e, 'code') and e.code in self.error_messages:
+                    message = self.error_messages[e.code]
+                    if e.params:
+                        message = message % e.params
+                    errors.append(message)
+                else:
+                    errors.extend(e.messages)
+        if errors:
+            raise exceptions.ValidationError(errors)
+
+    def validate(self, value, model_instance):
+        """
+        Validates value and throws ValidationError. Subclasses should override
+        this to provide validation logic.
+        """
+        if not self.editable:
+            # Skip validation for non-editable fields.
+            return
+        if self._choices and value:
+            if not value in dict(self.choices):
+                raise exceptions.ValidationError(self.error_messages['invalid_choice'] % value)
+
+        if value is None and not self.null:
+            raise exceptions.ValidationError(self.error_messages['null'])
+
+        if not self.blank and value in validators.EMPTY_VALUES:
+            raise exceptions.ValidationError(self.error_messages['blank'])
+
+    def clean(self, value, model_instance):
+        """
+        Convert the value's type and run validation. Validation errors from to_python
+        and validate are propagated. The correct value is returned if no error is
+        raised.
+        """
+        value = self.to_python(value)
+        self.validate(value, model_instance)
+        self.run_validators(value)
+        return value
+
     def db_type(self, connection):
         """
         Returns the database column data type for this field, for the provided
@@ -377,9 +468,12 @@ class Field(object):
         return getattr(obj, self.attname)
 
 class AutoField(Field):
-    description = ugettext_lazy("Integer")
+    description = _("Integer")
 
     empty_strings_allowed = False
+    default_error_messages = {
+        'invalid': _(u'This value must be an integer.'),
+    }
     def __init__(self, *args, **kwargs):
         assert kwargs.get('primary_key', False) is True, "%ss must have primary_key=True." % self.__class__.__name__
         kwargs['blank'] = True
@@ -391,8 +485,10 @@ class AutoField(Field):
         try:
             return int(value)
         except (TypeError, ValueError):
-            raise exceptions.ValidationError(
-                _("This value must be an integer."))
+            raise exceptions.ValidationError(self.error_messages['invalid'])
+
+    def validate(self, value, model_instance):
+        pass
 
     def get_prep_value(self, value):
         if value is None:
@@ -410,7 +506,10 @@ class AutoField(Field):
 
 class BooleanField(Field):
     empty_strings_allowed = False
-    description = ugettext_lazy("Boolean (Either True or False)")
+    default_error_messages = {
+        'invalid': _(u'This value must be either True or False.'),
+    }
+    description = _("Boolean (Either True or False)")
     def __init__(self, *args, **kwargs):
         kwargs['blank'] = True
         if 'default' not in kwargs and not kwargs.get('null'):
@@ -424,8 +523,7 @@ class BooleanField(Field):
         if value in (True, False): return value
         if value in ('t', 'True', '1'): return True
         if value in ('f', 'False', '0'): return False
-        raise exceptions.ValidationError(
-            _("This value must be either True or False."))
+        raise exceptions.ValidationError(self.error_messages['invalid'])
 
     def get_prep_lookup(self, lookup_type, value):
         # Special-case handling for filters coming from a web request (e.g. the
@@ -453,36 +551,35 @@ class BooleanField(Field):
         return super(BooleanField, self).formfield(**defaults)
 
 class CharField(Field):
-    description = ugettext_lazy("String (up to %(max_length)s)")
+    description = _("String (up to %(max_length)s)")
+
+    def __init__(self, *args, **kwargs):
+        super(CharField, self).__init__(*args, **kwargs)
+        self.validators.append(validators.MaxLengthValidator(self.max_length))
 
     def get_internal_type(self):
         return "CharField"
 
     def to_python(self, value):
-        if isinstance(value, basestring):
+        if isinstance(value, basestring) or value is None:
             return value
-        if value is None:
-            if self.null:
-                return value
-            else:
-                raise exceptions.ValidationError(
-                    ugettext_lazy("This field cannot be null."))
         return smart_unicode(value)
 
     def formfield(self, **kwargs):
+        # Passing max_length to forms.CharField means that the value's length
+        # will be validated twice. This is considered acceptable since we want
+        # the value in the form field (to pass into widget for example).
         defaults = {'max_length': self.max_length}
         defaults.update(kwargs)
         return super(CharField, self).formfield(**defaults)
 
 # TODO: Maybe move this into contrib, because it's specialized.
 class CommaSeparatedIntegerField(CharField):
-    description = ugettext_lazy("Comma-separated integers")
+    default_validators = [validators.validate_comma_separated_integer_list]
+    description = _("Comma-separated integers")
 
     def formfield(self, **kwargs):
         defaults = {
-            'form_class': forms.RegexField,
-            'regex': '^[\d,]+$',
-            'max_length': self.max_length,
             'error_messages': {
                 'invalid': _(u'Enter only digits separated by commas.'),
             }
@@ -493,9 +590,13 @@ class CommaSeparatedIntegerField(CharField):
 ansi_date_re = re.compile(r'^\d{4}-\d{1,2}-\d{1,2}$')
 
 class DateField(Field):
-    description = ugettext_lazy("Date (without time)")
+    description = _("Date (without time)")
 
     empty_strings_allowed = False
+    default_error_messages = {
+        'invalid': _('Enter a valid date in YYYY-MM-DD format.'),
+        'invalid_date': _('Invalid date: %s'),
+    }
     def __init__(self, verbose_name=None, name=None, auto_now=False, auto_now_add=False, **kwargs):
         self.auto_now, self.auto_now_add = auto_now, auto_now_add
         #HACKs : auto_now_add/auto_now should be done as a default or a pre_save.
@@ -516,8 +617,7 @@ class DateField(Field):
             return value
 
         if not ansi_date_re.search(value):
-            raise exceptions.ValidationError(
-                _('Enter a valid date in YYYY-MM-DD format.'))
+            raise exceptions.ValidationError(self.error_messages['invalid'])
         # Now that we have the date string in YYYY-MM-DD format, check to make
         # sure it's a valid date.
         # We could use time.strptime here and catch errors, but datetime.date
@@ -526,7 +626,7 @@ class DateField(Field):
         try:
             return datetime.date(year, month, day)
         except ValueError, e:
-            msg = _('Invalid date: %s') % _(str(e))
+            msg = self.error_messages['invalid_date'] % _(str(e))
             raise exceptions.ValidationError(msg)
 
     def pre_save(self, model_instance, add):
@@ -575,7 +675,10 @@ class DateField(Field):
         return super(DateField, self).formfield(**defaults)
 
 class DateTimeField(DateField):
-    description = ugettext_lazy("Date (with time)")
+    default_error_messages = {
+        'invalid': _(u'Enter a valid date/time in YYYY-MM-DD HH:MM[:ss[.uuuuuu]] format.'),
+    }
+    description = _("Date (with time)")
 
     def get_internal_type(self):
         return "DateTimeField"
@@ -596,8 +699,7 @@ class DateTimeField(DateField):
                 value, usecs = value.split('.')
                 usecs = int(usecs)
             except ValueError:
-                raise exceptions.ValidationError(
-                    _('Enter a valid date/time in YYYY-MM-DD HH:MM[:ss[.uuuuuu]] format.'))
+                raise exceptions.ValidationError(self.error_messages['invalid'])
         else:
             usecs = 0
         kwargs = {'microsecond': usecs}
@@ -614,8 +716,7 @@ class DateTimeField(DateField):
                     return datetime.datetime(*time.strptime(value, '%Y-%m-%d')[:3],
                                              **kwargs)
                 except ValueError:
-                    raise exceptions.ValidationError(
-                        _('Enter a valid date/time in YYYY-MM-DD HH:MM[:ss[.uuuuuu]] format.'))
+                    raise exceptions.ValidationError(self.error_messages['invalid'])
 
     def get_prep_value(self, value):
         return self.to_python(value)
@@ -642,7 +743,11 @@ class DateTimeField(DateField):
 
 class DecimalField(Field):
     empty_strings_allowed = False
-    description = ugettext_lazy("Decimal number")
+    default_error_messages = {
+        'invalid': _(u'This value must be a decimal number.'),
+    }
+    description = _("Decimal number")
+
     def __init__(self, verbose_name=None, name=None, max_digits=None, decimal_places=None, **kwargs):
         self.max_digits, self.decimal_places = max_digits, decimal_places
         Field.__init__(self, verbose_name, name, **kwargs)
@@ -656,8 +761,7 @@ class DecimalField(Field):
         try:
             return decimal.Decimal(value)
         except decimal.InvalidOperation:
-            raise exceptions.ValidationError(
-                _("This value must be a decimal number."))
+            raise exceptions.ValidationError(self.error_messages['invalid'])
 
     def _format(self, value):
         if isinstance(value, basestring) or value is None:
@@ -696,18 +800,15 @@ class DecimalField(Field):
         return super(DecimalField, self).formfield(**defaults)
 
 class EmailField(CharField):
-    description = ugettext_lazy("E-mail address")
+    default_validators = [validators.validate_email]
+    description = _("E-mail address")
+
     def __init__(self, *args, **kwargs):
         kwargs['max_length'] = kwargs.get('max_length', 75)
         CharField.__init__(self, *args, **kwargs)
 
-    def formfield(self, **kwargs):
-        defaults = {'form_class': forms.EmailField}
-        defaults.update(kwargs)
-        return super(EmailField, self).formfield(**defaults)
-
 class FilePathField(Field):
-    description = ugettext_lazy("File path")
+    description = _("File path")
 
     def __init__(self, verbose_name=None, name=None, path='', match=None, recursive=False, **kwargs):
         self.path, self.match, self.recursive = path, match, recursive
@@ -729,7 +830,10 @@ class FilePathField(Field):
 
 class FloatField(Field):
     empty_strings_allowed = False
-    description = ugettext_lazy("Floating point number")
+    default_error_messages = {
+        'invalid': _("This value must be a float."),
+    }
+    description = _("Floating point number")
 
     def get_prep_value(self, value):
         if value is None:
@@ -745,8 +849,7 @@ class FloatField(Field):
         try:
             return float(value)
         except (TypeError, ValueError):
-            raise exceptions.ValidationError(
-                _("This value must be a float."))
+            raise exceptions.ValidationError(self.error_messages['invalid'])
 
     def formfield(self, **kwargs):
         defaults = {'form_class': forms.FloatField}
@@ -755,7 +858,10 @@ class FloatField(Field):
 
 class IntegerField(Field):
     empty_strings_allowed = False
-    description = ugettext_lazy("Integer")
+    default_error_messages = {
+        'invalid': _("This value must be a float."),
+    }
+    description = _("Integer")
 
     def get_prep_value(self, value):
         if value is None:
@@ -771,8 +877,7 @@ class IntegerField(Field):
         try:
             return int(value)
         except (TypeError, ValueError):
-            raise exceptions.ValidationError(
-                _("This value must be an integer."))
+            raise exceptions.ValidationError(self.error_messages['invalid'])
 
     def formfield(self, **kwargs):
         defaults = {'form_class': forms.IntegerField}
@@ -781,7 +886,7 @@ class IntegerField(Field):
 
 class BigIntegerField(IntegerField):
     empty_strings_allowed = False
-    description = ugettext_lazy("Big (8 byte) integer")
+    description = _("Big (8 byte) integer")
     MAX_BIGINT = 9223372036854775807
     def get_internal_type(self):
         return "BigIntegerField"
@@ -794,7 +899,7 @@ class BigIntegerField(IntegerField):
 
 class IPAddressField(Field):
     empty_strings_allowed = False
-    description = ugettext_lazy("IP address")
+    description = _("IP address")
     def __init__(self, *args, **kwargs):
         kwargs['max_length'] = 15
         Field.__init__(self, *args, **kwargs)
@@ -809,7 +914,11 @@ class IPAddressField(Field):
 
 class NullBooleanField(Field):
     empty_strings_allowed = False
-    description = ugettext_lazy("Boolean (Either True, False or None)")
+    default_error_messages = {
+        'invalid': _("This value must be either None, True or False."),
+    }
+    description = _("Boolean (Either True, False or None)")
+
     def __init__(self, *args, **kwargs):
         kwargs['null'] = True
         Field.__init__(self, *args, **kwargs)
@@ -822,8 +931,7 @@ class NullBooleanField(Field):
         if value in ('None',): return None
         if value in ('t', 'True', '1'): return True
         if value in ('f', 'False', '0'): return False
-        raise exceptions.ValidationError(
-            _("This value must be either None, True or False."))
+        raise exceptions.ValidationError(self.error_messages['invalid'])
 
     def get_prep_lookup(self, lookup_type, value):
         # Special-case handling for filters coming from a web request (e.g. the
@@ -849,7 +957,7 @@ class NullBooleanField(Field):
         return super(NullBooleanField, self).formfield(**defaults)
 
 class PositiveIntegerField(IntegerField):
-    description = ugettext_lazy("Integer")
+    description = _("Integer")
 
     def get_internal_type(self):
         return "PositiveIntegerField"
@@ -860,7 +968,7 @@ class PositiveIntegerField(IntegerField):
         return super(PositiveIntegerField, self).formfield(**defaults)
 
 class PositiveSmallIntegerField(IntegerField):
-    description = ugettext_lazy("Integer")
+    description = _("Integer")
     def get_internal_type(self):
         return "PositiveSmallIntegerField"
 
@@ -870,7 +978,7 @@ class PositiveSmallIntegerField(IntegerField):
         return super(PositiveSmallIntegerField, self).formfield(**defaults)
 
 class SlugField(CharField):
-    description = ugettext_lazy("String (up to %(max_length)s)")
+    description = _("String (up to %(max_length)s)")
     def __init__(self, *args, **kwargs):
         kwargs['max_length'] = kwargs.get('max_length', 50)
         # Set db_index=True unless it's been set manually.
@@ -887,13 +995,13 @@ class SlugField(CharField):
         return super(SlugField, self).formfield(**defaults)
 
 class SmallIntegerField(IntegerField):
-    description = ugettext_lazy("Integer")
+    description = _("Integer")
 
     def get_internal_type(self):
         return "SmallIntegerField"
 
 class TextField(Field):
-    description = ugettext_lazy("Text")
+    description = _("Text")
 
     def get_internal_type(self):
         return "TextField"
@@ -904,9 +1012,12 @@ class TextField(Field):
         return super(TextField, self).formfield(**defaults)
 
 class TimeField(Field):
-    description = ugettext_lazy("Time")
+    description = _("Time")
 
     empty_strings_allowed = False
+    default_error_messages = {
+        'invalid': _('Enter a valid time in HH:MM[:ss[.uuuuuu]] format.'),
+    }
     def __init__(self, verbose_name=None, name=None, auto_now=False, auto_now_add=False, **kwargs):
         self.auto_now, self.auto_now_add = auto_now, auto_now_add
         if auto_now or auto_now_add:
@@ -935,8 +1046,7 @@ class TimeField(Field):
                 value, usecs = value.split('.')
                 usecs = int(usecs)
             except ValueError:
-                raise exceptions.ValidationError(
-                    _('Enter a valid time in HH:MM[:ss[.uuuuuu]] format.'))
+                raise exceptions.ValidationError(self.error_messages['invalid'])
         else:
             usecs = 0
         kwargs = {'microsecond': usecs}
@@ -949,8 +1059,7 @@ class TimeField(Field):
                 return datetime.time(*time.strptime(value, '%H:%M')[3:5],
                                          **kwargs)
             except ValueError:
-                raise exceptions.ValidationError(
-                    _('Enter a valid time in HH:MM[:ss[.uuuuuu]] format.'))
+                raise exceptions.ValidationError(self.error_messages['invalid'])
 
     def pre_save(self, model_instance, add):
         if self.auto_now or (self.auto_now_add and add):
@@ -983,21 +1092,17 @@ class TimeField(Field):
         return super(TimeField, self).formfield(**defaults)
 
 class URLField(CharField):
-    description = ugettext_lazy("URL")
+    description = _("URL")
 
     def __init__(self, verbose_name=None, name=None, verify_exists=True, **kwargs):
         kwargs['max_length'] = kwargs.get('max_length', 200)
-        self.verify_exists = verify_exists
         CharField.__init__(self, verbose_name, name, **kwargs)
-
-    def formfield(self, **kwargs):
-        defaults = {'form_class': forms.URLField, 'verify_exists': self.verify_exists}
-        defaults.update(kwargs)
-        return super(URLField, self).formfield(**defaults)
+        self.validators.append(validators.URLValidator(verify_exists=verify_exists))
 
 class XMLField(TextField):
-    description = ugettext_lazy("XML text")
+    description = _("XML text")
 
     def __init__(self, verbose_name=None, name=None, schema_path=None, **kwargs):
         self.schema_path = schema_path
         Field.__init__(self, verbose_name, name, **kwargs)
+
diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 7cc9a03907..749bdcf39a 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -7,7 +7,7 @@ from django.db.models.related import RelatedObject
 from django.db.models.query import QuerySet
 from django.db.models.query_utils import QueryWrapper
 from django.utils.encoding import smart_unicode
-from django.utils.translation import ugettext_lazy, string_concat, ungettext, ugettext as _
+from django.utils.translation import ugettext_lazy as _, string_concat, ungettext, ugettext
 from django.utils.functional import curry
 from django.core import exceptions
 from django import forms
@@ -473,7 +473,7 @@ def create_many_related_manager(superclass, rel=False):
             if not rel.through._meta.auto_created:
                 opts = through._meta
                 raise AttributeError, "Cannot use create() on a ManyToManyField which specifies an intermediary model. Use %s.%s's Manager instead." % (opts.app_label, opts.object_name)
-            new_obj = super(ManyRelatedManager, self).using(self.instance._state.db).create(**kwargs)
+            new_obj = super(ManyRelatedManager, self).create(**kwargs)
             self.add(new_obj)
             return new_obj
         create.alters_data = True
@@ -708,7 +708,10 @@ class ManyToManyRel(object):
 
 class ForeignKey(RelatedField, Field):
     empty_strings_allowed = False
-    description = ugettext_lazy("Foreign Key (type determined by related field)")
+    default_error_messages = {
+        'invalid': _('Model %(model)s with pk %(pk)r does not exist.')
+    }
+    description = _("Foreign Key (type determined by related field)")
     def __init__(self, to, to_field=None, rel_class=ManyToOneRel, **kwargs):
         try:
             to_name = to._meta.object_name.lower()
@@ -731,6 +734,18 @@ class ForeignKey(RelatedField, Field):
 
         self.db_index = True
 
+    def validate(self, value, model_instance):
+        if self.rel.parent_link:
+            return
+        super(ForeignKey, self).validate(value, model_instance)
+        if not value:
+            return
+        try:
+            self.rel.to._default_manager.get(**{self.rel.field_name:value})
+        except self.rel.to.DoesNotExist, e:
+            raise exceptions.ValidationError(
+                    self.error_messages['invalid'] % {'model': self.rel.to._meta.verbose_name, 'pk': value})
+
     def get_attname(self):
         return '%s_id' % self.name
 
@@ -812,7 +827,7 @@ class OneToOneField(ForeignKey):
     always returns the object pointed to (since there will only ever be one),
     rather than returning a list.
     """
-    description = ugettext_lazy("One-to-one relationship")
+    description = _("One-to-one relationship")
     def __init__(self, to, to_field=None, **kwargs):
         kwargs['unique'] = True
         super(OneToOneField, self).__init__(to, to_field, OneToOneRel, **kwargs)
@@ -826,6 +841,12 @@ class OneToOneField(ForeignKey):
             return None
         return super(OneToOneField, self).formfield(**kwargs)
 
+    def save_form_data(self, instance, data):
+        if isinstance(data, self.rel.to):
+            setattr(instance, self.name, data)
+        else:
+            setattr(instance, self.attname, data)
+
 def create_many_to_many_intermediary_model(field, klass):
     from django.db import models
     managed = True
@@ -866,7 +887,7 @@ def create_many_to_many_intermediary_model(field, klass):
     })
 
 class ManyToManyField(RelatedField, Field):
-    description = ugettext_lazy("Many-to-many relationship")
+    description = _("Many-to-many relationship")
     def __init__(self, to, **kwargs):
         try:
             assert not to._meta.abstract, "%s cannot define a relation with abstract class %s" % (self.__class__.__name__, to._meta.object_name)
@@ -886,7 +907,7 @@ class ManyToManyField(RelatedField, Field):
 
         Field.__init__(self, **kwargs)
 
-        msg = ugettext_lazy('Hold down "Control", or "Command" on a Mac, to select more than one.')
+        msg = _('Hold down "Control", or "Command" on a Mac, to select more than one.')
         self.help_text = string_concat(self.help_text, ' ', msg)
 
     def get_choices_default(self):