From 00a685178a6a8c1e2a3fe99ad20eb05d8533e175 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Honza=20Kr=C3=A1l?= <honza.kral@gmail.com>
Date: Wed, 13 Oct 2010 04:46:33 +0000
Subject: [PATCH] Fixed #14119 -- fields_for_model no longer returns all fields
 when fields parameter is the empty tuple. Thanks alexdutton!

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14199 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/forms/models.py                        |  4 +--
 .../model_forms_regress/tests.py              | 27 ++++++++++++++++++-
 .../model_formsets_regress/tests.py           |  8 ++++++
 3 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/django/forms/models.py b/django/forms/models.py
index d5d9fd1944..2f41dbf9df 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -40,7 +40,7 @@ def construct_instance(form, instance, fields=None, exclude=None):
         if not f.editable or isinstance(f, models.AutoField) \
                 or not f.name in cleaned_data:
             continue
-        if fields and f.name not in fields:
+        if fields is not None and f.name not in fields:
             continue
         if exclude and f.name in exclude:
             continue
@@ -168,7 +168,7 @@ def fields_for_model(model, fields=None, exclude=None, widgets=None, formfield_c
     for f in opts.fields + opts.many_to_many:
         if not f.editable:
             continue
-        if fields and not f.name in fields:
+        if fields is not None and not f.name in fields:
             continue
         if exclude and f.name in exclude:
             continue
diff --git a/tests/regressiontests/model_forms_regress/tests.py b/tests/regressiontests/model_forms_regress/tests.py
index 2b201a7ab1..4a88ce4800 100644
--- a/tests/regressiontests/model_forms_regress/tests.py
+++ b/tests/regressiontests/model_forms_regress/tests.py
@@ -2,7 +2,7 @@ import unittest
 from datetime import date
 
 from django import forms
-from django.forms.models import modelform_factory, ModelChoiceField
+from django.forms.models import modelform_factory, ModelChoiceField, fields_for_model, construct_instance
 from django.test import TestCase
 from django.core.exceptions import FieldError, ValidationError
 from django.core.files.uploadedfile import SimpleUploadedFile
@@ -417,3 +417,28 @@ class UniqueErrorsTests(TestCase):
         self.assertEquals(form.errors, {'__all__': [u'Edition with this Author and Publication already exists.']})
         form = EditionForm(data={'author': self.author2.pk, 'publication': self.pub1.pk, 'edition': 1, 'isbn': '9783161487777'})
         self.assertEquals(form.errors, {'__all__': [u'Edition with this Publication and Edition already exists.']})
+
+
+class EmptyFieldsTestCase(TestCase):
+    "Tests for fields=() cases as reported in #14119"
+    class EmptyPersonForm(forms.ModelForm):
+        class Meta:
+            model = Person
+            fields = ()
+
+    def test_empty_fields_to_fields_for_model(self):
+        "An argument of fields=() to fields_for_model should return an empty dictionary"
+        field_dict = fields_for_model(Person, fields=())
+        self.assertEqual(len(field_dict), 0)
+
+    def test_empty_fields_on_modelform(self):
+        "No fields on a ModelForm should actually result in no fields"
+        form = self.EmptyPersonForm()
+        self.assertEqual(len(form.fields), 0)
+
+    def test_empty_fields_to_construct_instance(self):
+        "No fields should be set on a model instance if construct_instance receives fields=()"
+        form = modelform_factory(Person)({'name': 'John Doe'})
+        self.assertTrue(form.is_valid())
+        instance = construct_instance(form, Person(), fields=())
+        self.assertEqual(instance.name, '')
diff --git a/tests/regressiontests/model_formsets_regress/tests.py b/tests/regressiontests/model_formsets_regress/tests.py
index ee2a26f6c2..2113623883 100644
--- a/tests/regressiontests/model_formsets_regress/tests.py
+++ b/tests/regressiontests/model_formsets_regress/tests.py
@@ -159,6 +159,14 @@ class InlineFormsetTests(TestCase):
         form = Form(instance=None)
         formset = FormSet(instance=None)
 
+    def test_empty_fields_on_modelformset(self):
+        "No fields passed to modelformset_factory should result in no fields on returned forms except for the id. See #14119."
+        UserFormSet = modelformset_factory(User, fields=())
+        formset = UserFormSet()
+        for form in formset.forms:
+            self.assertTrue('id' in form.fields)
+            self.assertEqual(len(form.fields), 1)
+
 
 class CustomWidget(forms.CharField):
     pass