Django UNIQUE约束失败：webapp_post.slug

Question

当我尝试创建新的Post对象时，Python喷出以下错误：

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报告说该数据库将不会保存您的Post数据，因为slug字段的值已被另一个Post 。

如果您不希望这种行为，请不要在模型中的Post.slug unique属性设置为True 。 但是请考虑一下，该slug通常用于查询数据库以找到关联的Post ，因此通常您希望它是唯一的。