django-forms:允许登录用户每个帖子只提交一条评论

Question

我有一个模型帖子，用户可以在其中留下评论和一组评分。我想限制每个帖子的用户评论只有一个。在我看来，我很难把它设置好

模型

class Comment(models.Model):
    post = models.ForeignKey(Post, related_name="comments")
    user = models.ForeignKey(User, related_name="usernamee")
    ...

class UserProfile(models.Model):
    user = models.OneToOneField(User, related_name='profile')

class Post(models.Model):
...

视图

def add_comment(request, slug):
    post = get_object_or_404(Post, slug=slug)

# I tried wrapping all of the below in an "if" statement, something like
# if request.user.comment.exists(): to check if the user has already
# left a comment on this specific post, but I'm not sure of the right way to perform such a check here.

    if request.method == 'POST':
            form = CommentForm(request.POST or None)
            if form.is_valid():
                comment = form.save(commit=False)
                comment.post = post 
                comment.user = request.user 
                comment.email = request.user.email
                comment.picture = request.user.profile.profile_image_url()

                comment.save()

                messages.success(request, "Thank you for leaving a review!")
                return redirect('blog:post_detail', slug=post.slug)

            else:
                messages.error(request, "Something went wrong! We weren't able to process your review :(")  
        else:
            form = CommentForm()



        template = "blog/post/add_comment.html"
        context = {

            'form': form,
            'post': post,
            #'comment_count': comment_count

            }
        return render(request, template, context)

我的印象是，我所需要的只是将我的add_comment视图中的整个表单代码包装在某种类型的验证系统中，该系统检查当前登录的用户是否已经在该特定帖子上留下了评论(请参阅评论)。

有人知道潜在的解决方案是什么吗？或者如果我这样做的话？

Answer 1

一种可能的解决办法是：

1. 查看当前的Post注释
2. 通过request.user过滤注释
3. 查看查询是否返回非空的查询集。

类似于：

from django.core.exceptions import PermissionDenied


def add_comment(request, slug):
    post = get_object_or_404(Post, slug=slug)

    # Get the comments posted by the user for this post
    user_comments = post.comments.filter(user=request.user)

    if request.method == 'POST':
            form = CommentForm(request.POST or None)

            # Check if there are any comments posted by the user
            if user_comments:
                # If there are any, raise an error
                raise PermissionDenied('You have already commented on this post.') 

            if form.is_valid():
                comment = form.save(commit=False)
                comment.post = post 
                comment.user = request.user 
                comment.email = request.user.email
                comment.picture = request.user.profile.profile_image_url()

                comment.save()

                messages.success(request, "Thank you for leaving a review!")
                return redirect('blog:post_detail', slug=post.slug)

            else:
                messages.error(request, "Something went wrong! We weren't able to process your review :(")  
    else:
        form = CommentForm()

    template = "blog/post/add_comment.html"
    context = {
        'form': form,
        'post': post
    }

    return render(request, template, context)

当然，您可以在这里修改引发的错误，但是主要的想法是获取注释并通过request.user对它们进行筛选，并查看是否存在。