django，FOREIGN KEY约束失败

Question

I have to insert the post through a form but when i submit i got this error FOREIGN KEY constraint failed, the problem is with the author field

models.py

class Post(models.Model):
    STATUS_CHOICES = (
        ('draft','Draft'),
        ('published','Published'),
    )

    title = models.CharField(max_length=100)
    slug = models.SlugField(max_length=120)
    author = models.ForeignKey('auth.User',related_name='blog_posts',on_delete=models.CASCADE,blank=True, null=True)
    body = RichTextField()
    created = models.DateTimeField(auto_now=True)
    status = models.CharField(max_length=10,choices=STATUS_CHOICES,default='draft')
    tag = models.OneToOneField(Tag,related_name="blog_tag",on_delete=models.CASCADE,default=0)

    def __str__(self):
        return self.title

views.py

def tagView(request,name):
    tag = Tag.objects.get(name=name)
    post_form = PostForm(request.POST or None)
    if request.method == 'POST':
        post_form = PostForm(request.POST)
        if post_form.is_valid():
            item = post_form.save(commit=False)
            item.author = request.user
            item.save()

            return HttpResponseRedirect(request.path_info)
    context = {
        'post_form' : post_form,
        'tag' : tag,
    }
    return render(request,'blog/tagPage.html',context)

forms.py

class PostForm(forms.ModelForm):

    class Meta:
        model = Post
        fields = ['title','body']

template

<form class="post-form" method="POST" enctype="multipart/form-data" action="">
    {% csrf_token %}
    {{ post_form }}
    <input class="post-form-submit submit" type="submit" value="Save">
  </form>

Answer 1

如果作者字段是问题，请确保导入auth.User

Answer 2

My guess is that you are trying to add the post as anonymous but anonymous user is not null (id is though). Also don't use 'auth.User' and follow the instructions from the documentation .