Django唯一约束失败: webapp_post.slug

Question

当我试图创建一个新的Post对象时，Python输出了以下错误：

UNIQUE constraint failed: webapp_post.slug

这是我的models.py

class Post(models.Model):
    title = models.CharField(max_length=200)
    slug = models.SlugField(unique=True)
    text = models.TextField()
    created_on = models.DateTimeField(auto_now_add=True)
    up_vote = 0 # num of up votes
    down_vote = 0 #num of down votes
    vote_total = up_vote - down_vote
    author = models.ForeignKey('auth.User', null=True, blank=True)

    CHOICES = [
        ('Hardware and OS', 'Hardware and OS'),
        ('Desktops', 'Desktops'),
        ('Tablets', 'Tablets'),
        ('Phones', 'Phones'),
        ('Wearables', 'Wearables'),
        ('Windows', 'Windows'),
        ('Mac OS X', 'Mac OS X'),
        ('Linux and Unix', 'Linux and Unix'),
        ('Programming and Computer Science', 'Programming and Computer Science'),
        ('Software Development', 'Software Development'),
        ('Web Development (Front)', 'Web Development (Front)'),
        ('Web Development (Back)', 'Web Development (Back)'),
        ('Mobile Development', 'Mobile Development'),
        ('Game Development', 'Game Development'),
        ('Algorithms and Data Structures', 'Algorithms and Data Structures'),
        ('Databases', 'Databases'),
        ('IDE / Text Editors', 'IDE / Text Editors'),
        ('Tutorial', 'Tutorial'),
        ('Opinion', 'Opinion'),
        ('Miscellaneous', 'Miscellaneous')
    ]
    field = models.CharField(choices=CHOICES, max_length=200)

    def __unicode__(self):
        return self.title

    @models.permalink
    def get_absolute_url(self):
        return ('blog_post_detail', (), 
                {
                    'slug' :self.slug,
                })

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = slugify(self.title)
        super(Post, self).save(*args, **kwargs)

这是我的views.py

@user_passes_test(lambda u: u.is_authenticated)
def add_post(request):
    form = PostForm(request.POST or None)

    if request.method == "POST":
        if form.is_valid() and request.user.is_authenticated():
            try:
                post = form.save(commit=False)
                post.author = request.user
                post.save()
                Post.objects.create(author=request.user, title=form.cleaned_data.get("title"), text=form.cleaned_data.get("text"))
                return redirect(post)
            except IntegrityError as e:
                print(e)
        else:
            print("Invalid form")
            print(form.errors)

    return render_to_response('webapp/startthread.html', 
                              { 'form': form,
                                "authenticated": request.user.is_authenticated() },
                              context_instance=RequestContext(request))

Answer 1

Django报告说，数据库不会保存Post数据，因为另一个Post已经在使用slug字段的值。

如果不希望这种行为，请不要在模型中将unique属性设置为Post.slug上的True。不过，请考虑一下，slug通常用于查询数据库以查找相关的Post，因此通常您希望它是唯一的。