Django中自定义标签的使用

绝地灬酷狼 2023-02-18 14:11 17阅读 0赞

### 问题描述： ###

在Django开发中，我们增加一个功能的时候，如：评论功能，因为需要在不同的页面下实现展示评论和提交评论的功能，所以可能需要修改不同页面对应的视图函数，这样极大的提高了代码的维护成本。

### 问题解决： ###

这个时候，我们可以借助Django的自定义标签来实现评论的功能，把评论功能对应的数据操作放在标签函数中去实现，这样就可以减少代码的耦合，降低维护成本。

### 自定义标签的使用： ###

（1）评论Comment对应的model定义：  
models.py

from django.db import models
    
    
    # Create your models here.
    class Comment(models.Model):
        STATUS_NORMAL = 1
        STATUS_DELETE = 0
        STATUS_ITEMS = (
            (STATUS_NORMAL, '正常'),
            (STATUS_DELETE, '删除'),
        )
    
        # target = models.ForeignKey(Post, verbose_name='评论目标')
        target = models.CharField(max_length=100, verbose_name='评论目标')
        content = models.CharField(max_length=500, verbose_name='内容')
        nickname = models.CharField(max_length=50, verbose_name='昵称')
        website = models.URLField(verbose_name='网站')
        email = models.EmailField(verbose_name='邮箱')
        status = models.PositiveIntegerField(default=STATUS_NORMAL, choices=STATUS_ITEMS,
                                             verbose_name='状态')
        created_time = models.DateTimeField(auto_now_add=True, verbose_name='创建时间')
    
        class Meta:
            verbose_name = verbose_name_plural = '评论'
            ordering = ['-created_time']  # 根据created_time进行降序排序
    
        @classmethod
        def get_by_target(cls, target):
            return cls.objects.filter(target=target, status=cls.STATUS_NORMAL)

（2）评论对应的后台配置：  
admin.py

from django.contrib import admin
    
    from .models import Comment
    
    
    # Register your models here.
    @admin.register(Comment)
    class CommentAdmin(admin.ModelAdmin):
        list_display = ('target', 'nickname', 'content', 'website', 'created_time')

（3）评论表单form的定义，在comment应用目录下，新建forms.py:  
forms.py:

import mistune
    
    from django import forms
    
    from .models import Comment
    
    
    class CommentForm(forms.ModelForm):
        nickname = forms.CharField(
            label='昵称',
            max_length=50,
            widget=forms.widgets.Input(
                attrs={
        'class': 'form-control', 'style': "width: 60%;"}
            )
        )
        email = forms.CharField(
            label='Email',
            max_length=50,
            widget=forms.widgets.EmailInput(
                attrs={
        'class': 'form-control', 'style': "width: 60%;"}
            )
        )
        website = forms.CharField(
            label='网站',
            max_length=100,
            widget=forms.widgets.URLInput(
                attrs={
        'class': 'form-control', 'style': "width: 60%;"}
            )
        )
    
        content = forms.CharField(
            label="内容",
            max_length=500,
            widget=forms.widgets.Textarea(
                attrs={
        'rows': 6, 'cols': 60, 'class': 'form-control'}
            )
        )
    
        # 对评论内容进行验证
        def clean_content(self):
            content = self.cleaned_data.get('content')
            if len(content) < 1:
                raise forms.ValidationError('内容长度怎么能这么短呢！！')
            content = mistune.markdown(content)
            return content
    
        class Meta:
            model = Comment
            fields = ['nickname', 'email', 'website', 'content']

（4）创建comment自定义标签，在在comment应用目录下，新建templatetags目录，在该目录下新建\_\_init\_\_.py和comment\_block.py文件。  
在comment\_block.py文件中编写自定义标签的代码：  
comment/templatetags/comment\_block.py：

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    from django import template
    
    from comment.forms import CommentForm
    from comment.models import Comment
    
    register = template.Library()
    
    
    @register.inclusion_tag('comment/block.html')
    def comment_block(target):
        return {
        
            'target': target,
            'comment_form': CommentForm(),
            'comment_list': Comment.get_by_target(target)
        }

（5）编写模板文件comment/block.html：  
comment/block.html：  
**注意**：因为我们在后面的detail.html中引入了css文件：bootstrap.css，所以我们在block.html中使用了bootstrap.css中定义的一些样式。

<hr/>
    <div class="comment">
        <form class="form-group" action="/comment/" method="POST">
            {% csrf_token %}
            <input name="target" type="hidden" value="{
         { target }}"/>
            {
       { comment_form }}
            <input type="submit" value="submit">
        </form>
        
        <ul class="list-group">
            {% for comment in comment_list %}
            <li class="list-group-item">
                <div class="nickname">
                    <a href="{
         { comment.website }}">{
       { comment.nickname }}</a>
                    <span>{
       { comment.created_time}}</span>
                </div>
                <div class="comment-content">
                    {
       { comment.content }}
                </div>
            </li>
            {% endfor %}
        </ul>
    </div>

（6）在其他页面添加评论功能，如在文章详情页detail.html加入评论功能，  
1、在detail.html的开头引入评论的模板标签：

{% load comment_block %}

2、在detail.html中需要引入评论的位置添加：

{% comment_block request.path post.title %}

即可引入评论的功能。  
（7）在评论的form中（block.html），

提交评论的时候，访问了action="/comment/"，所以需要在urls.py中配置该路径对应的URL，并且在该URL对应的视图函数中，对评论的数据进行验证和保存。  
1、urls.py代码：

"""typeidea URL Configuration
    
    The `urlpatterns` list routes URLs to views. For more information please see:
        https://docs.djangoproject.com/en/1.11/topics/http/urls/
    Examples:
    Function views
        1. Add an import:  from my_app import views
        2. Add a URL to urlpatterns:  url(r'^$', views.home, name='home')
    Class-based views
        1. Add an import:  from other_app.views import Home
        2. Add a URL to urlpatterns:  url(r'^$', Home.as_view(), name='home')
    Including another URLconf
        1. Import the include() function: from django.conf.urls import url, include
        2. Add a URL to urlpatterns:  url(r'^blog/', include('blog.urls'))
    """
    from django.conf.urls import url
    from django.contrib import admin
    
    from blog.views import (
        IndexView, CategoryView, TagView,
        PostDetailView
    )
    from comment.views import CommentView
    
    urlpatterns = [
        url(r'^$', IndexView.as_view(), name='index'),  # 首页
        url(r'^category/(?P<category_id>\d+)/$', CategoryView.as_view(), name='category-list'),  # 分类列表页
        url(r'^tag/(?P<tag_id>\d+)/$', TagView.as_view(), name='tag-list'),  # tag列表页
        url(r'post/(?P<post_id>\d+).html$', PostDetailView.as_view(), name='post-detail'),  # 文章详情页
        url(r'^comment/$', CommentView.as_view(), name='comment'),  # 评论提交
    
        url(r'^admin/', admin.site.urls),
    ]

2、实现视图函数comment/views.py：

from django.shortcuts import redirect
    from django.views.generic import TemplateView
    
    from .forms import CommentForm
    
    
    class CommentView(TemplateView):
        http_method_names = ['post']
        template_name = 'comment/result.html'
    
        def post(self, request, *args, **kwargs):
            comment_form = CommentForm(request.POST)
            target = request.POST.get('target')
    
            if comment_form.is_valid():
                instance = comment_form.save(commit=False)
                instance.target = target
                instance.save()
                succeed = True
                return redirect(target)  # 评论成功，返回原评论页面
            else:
                succeed = False
    
            context = {
        
                'succeed': succeed,
                'form': comment_form,
                'target': target
            }
            return self.render_to_response(context)  # 提交数据失败，则去到评论结果页comment/result.html。

3、评论结果页comment/result.html:

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>评论结果页</title>
        <style>
            body {
         TEXT-ALIGN: center;}
            .result {
         
                text-align: center;
                width: 40%;
                margin: auto;
            }
            .errorlist {
         color: red;}
            ul li {
         
                list-style-type: None;
            }
        </style>
    </head>
    <body>
    <div class="result">
        {% if succeed %}
        评论成功！
        <a href="{
         { target }}">返回</a>
        {% else %}
        <ul class="errorlist">
            {% for field, message in form.errors.items %}
            <li>字段{
       { field }}：{
       { message }}</li>
            {% endfor %}
        </ul>
        <a href="javascript:window.history.back();">返回</a>
        {% endif %}
    </div>
    </body>
    </html>

（8）结果演示：  
文章详情页：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1YW5tYW9uaW5n_size_16_color_FFFFFF_t_70]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1YW5tYW9uaW5n_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200618104520510.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1YW5tYW9uaW5n,size_16,color_FFFFFF,t_70