如何使用django-mptt创建嵌套注释系统

Question

我正在开发简单的博客，我正在尝试为每个帖子实现一个嵌套的评论系统。

我创建了评论模型，它通过Django Admin Page工作正常。

我不知道如何创建表单来发布新评论和回复。

这是我到目前为止：

models.py

(...)
class Post(models.Model):
    author = models.ForeignKey('Author', on_delete=models.CASCADE)
    title = models.CharField(max_length=250)
    slug = models.SlugField(unique=True, blank=True, max_length=250)
    created = models.DateTimeField(auto_now=False, auto_now_add=True)
    modified = models.DateTimeField(auto_now=True, auto_now_add=False)
    tags = TaggableManager(blank=True)
    image = models.ImageField(upload_to="images/%Y/%m/", blank=True, null=True)
    content = models.TextField()

    def get_absolute_url(self):
        return reverse('post_detail', kwargs={'slug': self.slug, })

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

    def __str__(self):
        return str(self.title)

class Comment(MPTTModel):
    post = models.ForeignKey("Post", on_delete=models.CASCADE, null=True, related_name='comments')
    parent = TreeForeignKey('self', null=True, blank=True, related_name='replies', db_index=True)

    name = models.CharField(max_length=250)
    email = models.EmailField(max_length=250, blank=True, null=True)
    website = models.CharField(max_length=250, blank=True, null=True)
    created = models.DateTimeField(auto_now=False, auto_now_add=True)
    content = models.TextField()

    def __str__(self):
        return str("{}: {}...".format(self.name, self.content[:50]))

forms.py

class CommentForm(forms.ModelForm):

    class Meta:
        model = Comment
        fields = [ "name", 'email', 'website', 'content']

views.py

class PostDetailView(DetailView):
    model = Post

    def get_context_data(self, **kwargs):
        context = super(PostDetailView, self).get_context_data(**kwargs)
        context['form'] = CommentForm()
        return context


class PostCommentView(SingleObjectMixin, FormView):
    template_name = 'blog/post_detail.html'
    form_class = CommentForm
    model = Post

    def post(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super(PostCommentView, self).post(request, *args, **kwargs)

    def get_success_url(self):
        return reverse('post_detail', kwargs={'slug': self.object.slug})

class PostDetail(View):

    def get(self, request, *args, **kwargs):
        view = PostDetailView.as_view()
        return view(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        view = PostCommentView.as_view()
        return view(request, *args, **kwargs)

comment_form.html

<div id="respond">
    <h2 class="respond-title">Leave a comment</h2>
    <span class="form-caution">Make sure you enter the (*) required information where indicated. HTML code is not allowed.</span>
    <form action="" method="post">
        {{ form.non_field_errors }}
        {% csrf_token %}
        {{  form }}
         <input name="submit" type="submit" id="submit" class="btn btn-primary" value="Submit Comment">
    </form>
</div>

Answer 1

一般来说

修改的预订树遍历不是构建嵌套注释的最佳解决方案。 考虑到每个新节点都必须重建整个树。 例如，让我们想象一下帖子F下的评论：

//             F
//           / | \
//          B  X  G
//         / \
//        Z   Y

请注意，注释X的值为8，右值为9.但是，对于B或X的每个新子注释，这些值都将更改。 例如，评论中的新评论X的X值将变为lft = 10和rht = 11.这可能导致糟糕的性能，并且正如我想象的那样，在信使的情况下丢失数据意味着信息仅发送一次（例如， Django频道）。

---

定制现成的解决方案

本文通过连接内置评论应用程序和mptt来提供实现嵌套表达系统的解决方案。 这是一个旧帖子，自Django 1.6以来， django.contrib.comments已被分离为一个单独的项目 。 最近Tim Graham添加了支持Django 2.0的更改，因此它似乎是最新的。

我们的想法是创建一个自定义模型和表单，它将添加到Django_comments的标题字段中。 该帖子建议将其连接起来：

Models.py

from django_comments.models import Comment
from mptt.models import MPTTModel, TreeForeignKey

class MPTTComment(MPTTModel, Comment):
    """ Threaded comments - Add support for the parent comment store and MPTT traversal"""

    # a link to comment that is being replied, if one exists
    parent = TreeForeignKey('self', null=True, blank=True, related_name='children')

    class MPTTMeta:
        # comments on one level will be ordered by date of creation
        order_insertion_by=['submit_date']

    class Meta:
        ordering=['tree_id','lft']

Forms.py

from django import forms
from django.forms.widgets import widgets        
from django_comments.forms import CommentForm                            
from models import MPTTComment

class MPTTCommentForm(CommentForm):
    parent = forms.ModelChoiceField(queryset=MPTTComment.objects.all(),
        required=False, widget=forms.HiddenInput)

    def get_comment_model(self):
        # Use our custom comment model instead of the built-in one.
        return MPTTComment

    def get_comment_create_data(self):
        # Use the data of the superclass, and add in the parent field field
        data = super(MPTTCommentForm, self).get_comment_create_data()
        data['parent'] = self.cleaned_data['parent']
        return data

您的app目录中的__init__.py

from models import MPTTComment
from forms import MPTTCommentForm

def get_model():
    return MPTTComment

def get_form():
    return MPTTCommentForm

---

还有另一个django包，这个包含已嵌入的嵌套注释： django-threadedcomments 。 值得一试。