Made model fields comparable to other objects (5cbfb48b) · Commits · Dom Sekotill / django

django/db/models/fields/init.py

+12 −3

Original line number	Diff line number	Diff line
		@@ -12,7 +12,7 @@ from django import forms
		from django.core import exceptions, validators
		from django.utils.datastructures import DictWrapper
		from django.utils.dateparse import parse_date, parse_datetime, parse_time
		from django.utils.functional import curry
		from django.utils.functional import curry, total_ordering
		from django.utils.text import capfirst
		from django.utils import timezone
		from django.utils.translation import ugettext_lazy as _
		@@ -45,6 +45,7 @@ class FieldDoesNotExist(Exception):
		#
		# getattr(obj, opts.pk.attname)

		@total_ordering
		class Field(object):
		"""Base class for all field types"""

		@@ -118,9 +119,17 @@ class Field(object):
		messages.update(error_messages or {})
		self.error_messages = messages

		def __cmp__(self, other):
		def __eq__(self, other):
		# Needed for @total_ordering
		if isinstance(other, Field):
		return self.creation_counter == other.creation_counter
		return NotImplemented

		def __lt__(self, other):
		# This is needed because bisect does not take a comparison function.
		return cmp(self.creation_counter, other.creation_counter)
		if isinstance(other, Field):
		return self.creation_counter < other.creation_counter
		return NotImplemented

		def __deepcopy__(self, memodict):
		# We don't have to deepcopy very much here, since most things are not

django/utils/functional.py

+32 −0

Original line number	Diff line number	Diff line
		@@ -310,3 +310,35 @@ def partition(predicate, values):
		for item in values:
		results[predicate(item)].append(item)
		return results

		try:
		from functools import total_ordering
		except ImportError:
		# For Python < 2.7
		# Code borrowed from python 2.7.3 stdlib
		def total_ordering(cls):
		"""Class decorator that fills in missing ordering methods"""
		convert = {
		'__lt__': [('__gt__', lambda self, other: not (self < other or self == other)),
		('__le__', lambda self, other: self < other or self == other),
		('__ge__', lambda self, other: not self < other)],
		'__le__': [('__ge__', lambda self, other: not self <= other or self == other),
		('__lt__', lambda self, other: self <= other and not self == other),
		('__gt__', lambda self, other: not self <= other)],
		'__gt__': [('__lt__', lambda self, other: not (self > other or self == other)),
		('__ge__', lambda self, other: self > other or self == other),
		('__le__', lambda self, other: not self > other)],
		'__ge__': [('__le__', lambda self, other: (not self >= other) or self == other),
		('__gt__', lambda self, other: self >= other and not self == other),
		('__lt__', lambda self, other: not self >= other)]
		}
		roots = set(dir(cls)) & set(convert)
		if not roots:
		raise ValueError('must define at least one ordering operation: < > <= >=')
		root = max(roots) # prefer __lt__ to __le__ to __gt__ to __ge__
		for opname, opfunc in convert[root]:
		if opname not in roots:
		opfunc.__name__ = opname
		opfunc.__doc__ = getattr(int, opname).__doc__
		setattr(cls, opname, opfunc)
		return cls

tests/modeltests/basic/tests.py

+17 −1

Original line number	Diff line number	Diff line
		@@ -3,7 +3,7 @@ from __future__ import absolute_import
		from datetime import datetime

		from django.core.exceptions import ObjectDoesNotExist
		from django.db.models.fields import FieldDoesNotExist
		from django.db.models.fields import Field, FieldDoesNotExist
		from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
		from django.utils.translation import ugettext_lazy

		@@ -520,6 +520,22 @@ class ModelTest(TestCase):
		s = set([a10, a11, a12])
		self.assertTrue(Article.objects.get(headline='Article 11') in s)

		def test_field_ordering(self):
		"""
		Field instances have a `__lt__` comparison function to define an
		ordering based on their creation. Prior to #17851 this ordering
		comparison relied on the now unsupported `__cmp__` and was assuming
		compared objects were both Field instances raising `AttributeError`
		when it should have returned `NotImplemented`.
		"""
		f1 = Field()
		f2 = Field(auto_created=True)
		f3 = Field()
		self.assertTrue(f2 < f1)
		self.assertTrue(f3 > f1)
		self.assertFalse(f1 == None)
		self.assertFalse(f2 in (None, 1, ''))

		def test_extra_method_select_argument_with_dashes_and_values(self):
		# The 'select' argument to extra() supports names with dashes in
		# them, as long as you use values().