[py3] Refactored __unicode__ to __str__.

* Renamed the __unicode__ methods
* Applied the python_2_unicode_compatible decorator
* Removed the StrAndUnicode mix-in that is superseded by
  python_2_unicode_compatible
* Kept the __unicode__ methods in classes that specifically
  test it under Python 2

tests/modeltests/fixtures/models.py

@@ -12,38 +12,43 @@ from django.contrib.auth.models import Permission
 from django.contrib.contenttypes import generic
 from django.contrib.contenttypes.models import ContentType
 from django.db import models
+from django.utils.encoding import python_2_unicode_compatible
 
 
+@python_2_unicode_compatible
 class Category(models.Model):
     title = models.CharField(max_length=100)
     description = models.TextField()
 
-    def __unicode__(self):
+    def __str__(self):
         return self.title
 
     class Meta:
         ordering = ('title',)
 
+@python_2_unicode_compatible
 class Article(models.Model):
     headline = models.CharField(max_length=100, default='Default headline')
     pub_date = models.DateTimeField()
 
-    def __unicode__(self):
+    def __str__(self):
         return self.headline
 
     class Meta:
         ordering = ('-pub_date', 'headline')
 
+@python_2_unicode_compatible
 class Blog(models.Model):
     name = models.CharField(max_length=100)
     featured = models.ForeignKey(Article, related_name='fixtures_featured_set')
     articles = models.ManyToManyField(Article, blank=True,
                                       related_name='fixtures_articles_set')
 
-    def __unicode__(self):
+    def __str__(self):
         return self.name
 
 
+@python_2_unicode_compatible
 class Tag(models.Model):
     name = models.CharField(max_length=100)
     tagged_type = models.ForeignKey(ContentType, related_name="fixtures_tag_set")
@@ -51,7 +56,7 @@ class Tag(models.Model):
     tagged = generic.GenericForeignKey(ct_field='tagged_type',
                                        fk_field='tagged_id')
 
-    def __unicode__(self):
+    def __str__(self):
         return '<%s: %s> tagged "%s"' % (self.tagged.__class__.__name__,
                                          self.tagged, self.name)
 
@@ -59,10 +64,11 @@ class PersonManager(models.Manager):
     def get_by_natural_key(self, name):
         return self.get(name=name)
 
+@python_2_unicode_compatible
 class Person(models.Model):
     objects = PersonManager()
     name = models.CharField(max_length=100)
-    def __unicode__(self):
+    def __str__(self):
         return self.name
 
     class Meta:
@@ -79,19 +85,21 @@ class Spy(Person):
     objects = SpyManager()
     cover_blown = models.BooleanField(default=False)
 
+@python_2_unicode_compatible
 class Visa(models.Model):
     person = models.ForeignKey(Person)
     permissions = models.ManyToManyField(Permission, blank=True)
 
-    def __unicode__(self):
+    def __str__(self):
         return '%s %s' % (self.person.name,
                           ', '.join(p.name for p in self.permissions.all()))
 
+@python_2_unicode_compatible
 class Book(models.Model):
     name = models.CharField(max_length=100)
     authors = models.ManyToManyField(Person)
 
-    def __unicode__(self):
+    def __str__(self):
         authors = ' and '.join(a.name for a in self.authors.all())
         return '%s by %s' % (self.name, authors) if authors else self.name