Django：reverse反转URL并传递参数

需求：

　　假设在文章详情页评论文章后需要重新刷新显示该页面（原始方法，提交评论表单为form方式，未采用ajax方式），

提交评论后代码会走comment的视图函数，等数据入库之后需要将页面重新定位到文章详情页面。

article_detail2.html页面

<!-- article_detail2.html -->

<!-- 发表评论 -->
    <br>
    {% if user.is_authenticated %}
        <div>
            <form
                action="{% url 'comment:post_comment' article.id %}"
                method="POST"
            >
            {% csrf_token %}
                <div class="form-group">
                    <label for="body">
                        <strong>
                            我也要发言：
                        </strong>
                    </label>
                    <textarea
                        type="text"
                        class="form-control"
                        id="body"
                        name="body"
                        rows="2"></textarea>
                </div>
                <!-- 提交按钮 -->
                <button type="submit" class="btn btn-primary ">发送</button>
            </form>
        </div>
        <br>
    {% else %}
        <br>
        <h5 class="row justify-content-center">
            请<a href="{% url 'account:user_login' %}">登录</a>后回复
        </h5>
        <br>
    {% endif %}

URL路由

from django.conf.urls import url
from . import views, list_views
from haystack.views import SearchView


urlpatterns=[
    url(r'^article-column/$', views.article_column, name='article_column'),
    url(r'^rename-column/$', views.rename_article_column, name='rename_article_column'),
    url(r'^delete-column/$', views.delete_article_column, name='delete_column'),
    url(r'^post-article/$', views.article_post, name='article_post'),
    url(r'^article-list/$', views.article_list, name='article_list'),
    url(r'^delete-article/$', views.delete_article, name='delete_article'),
    url(r'^article-detail/(?P<id>d+)/(?P<slug>[-w]+)/$', views.article_detail, name='article_detail'),
    url(r'^re-edit-article/(?P<article_id>d+)$', views.re_edit_article, name='re_edit_article'),
    url(r'^list-article-titles/$', list_views.article_titles, name='list_article_titles'),
    url(r'^list-article-titles-bysomeone/(?P<author>[-w]+)/$', list_views.article_titles_by_someone, name='list_article_titles_bysomeone'),

    url(r'^upload/$', views.upload_img, name='upload_img'),
    # url(r'^search/$', views.MySeachView, name='haystack_search'),
    # SearchView()视图函数，默认使用的HTML模板路径为templates/search/search.html
    url(r'search/$', SearchView(), name='haystack_search'),
]

评论视图函数： 

from django.http import HttpResponse
from django.shortcuts import render, get_object_or_404, redirect, reverse

from article.models import ArticlePost
from comment.forms import CommentForm
from .models import Comment
from utils.decorators import login_wrapper

# Create your views here.

# @login_wrapper
def post_comment(request, article_id, parent_comment_id=None):
    article = get_object_or_404(ArticlePost, id=article_id)
    slug = article.slug
    print(article_id, parent_comment_id)
    # 处理post请求
    if request.method == 'POST':
        comment_form = CommentForm(request.POST)
        if comment_form.is_valid():
            new_comment = comment_form.save(commit=False)
            new_comment.article = article
            new_comment.user = request.user

            # 二级回复
            if parent_comment_id:
                print('已请求')
                parent_comment = Comment.objects.get(id=parent_comment_id)
                # 若回复层级超过两级，则转为二级
                new_comment.parent_id = parent_comment.get_root().id
                # 被回复人
                new_comment.reply_to = parent_comment.user
                new_comment.save()
                print('评论已写入')
                return HttpResponse('200 OK')

            new_comment.save()
            # 评论完成刷新该页面,后面优化为aja提交数据，局部刷新
            # return redirect('article:list_article_titles')
            # reverse反转url时需要传参数，要用到kwargs参数，会传入一个字典类型的参数
            article_detail_url = reverse('article:article_detail', kwargs={'id': article_id, 'slug': slug})
            return redirect(article_detail_url)
        else:
            return HttpResponse("表单有误，重新填写")

    elif request.method == 'GET':
        print('获取评论')
        comment_form = CommentForm()
        context = {
            'comment_form': comment_form,
            'article_id': article_id,
            'parent_comment_id': parent_comment_id
        }
        return render(request, 'comment/reply.html', context)

    else:
        return HttpResponse("仅接受get或者post请求")

其中可以看到这两行：

article_detail_url = reverse('article:article_detail', kwargs={'id':article_id,'slug':slug})
return redirect(article_detail_url)

在评论视图中如果采用硬编码方式则为

article_detail_url = 'article/article-detail/%s/%s' % (article_id,slug)
return redirect(article_detail_url)

这样做的坏处就是，如果当文章详情页面的url变化之后，这里也要跟着修改，不符合DRY原则（Don`t Repeat Yourself）

使用reverse函数（意思是逆向、反转）代码中只要写对应url的name就实现了从name到path的转换，那为什么叫反转呢，因为URL配置中实现的是从path到name。