Django模板无法向head标签添加内容问题排查

我有如下几个模板文件：

bootstrap.html #

{% extends 'django_bootstrap5/bootstrap5.html' %} 
{% block bootstrap5_title %}{% block title %}{% endblock %}{% endblock %}

sm/base.html #

{% extends 'sm/bootstrap.html' %}

{% load django_bootstrap5 %}

{% block head %}
 <meta name="robots" content="all, index, follow" />
{% endblock %}

{% block bootstrap5_content %}
    <div class="container">
        <h1>{% block title %}(no title){% endblock %}</h1>
        {% autoescape off %}{% bootstrap_messages %}{% endautoescape %}
        {% block content %}(no content){% endblock %}
    </div>

{% endblock %}

sm/home.html #

{% extends 'sm/base.html' %}
{% load django_bootstrap5 %}


{% block title %}My title{% endblock %}

{% block head %}
 <meta name="robots" content="all, index, follow" />
{% endblock %}

{% block content %}
    <br/>
    
{% endblock %}

查看页面输出时，head标签中并未出现robots元标签，页面输出片段如下：

<!DOCTYPE html>
<!DOCTYPE html>
<html lang="en-ie">
<head>

<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

<title>My title</title>

<link crossorigin="anonymous" href="https://cdn.jsdelivr.net/npm/bootstrap@5.2.3/dist/css/bootstrap.min.css" integrity="sha384-rbsA2VBKQhggwzxH7pPCaAqO46MgnOM80zW1RWuH61DGLwZJEdK2Kadq2F9CUG65" rel="stylesheet">

</head>
<body> ...

问题原因 #

你在子模板中定义的head块，在父模板django_bootstrap5/bootstrap5.html里根本不存在。Django模板系统只会渲染父模板中已定义的块，子模板里新增的、父模板没有的块会被直接忽略。

解决办法 #

django-bootstrap5的基础模板bootstrap5.html中，专门用于扩展head内容的块是bootstrap5_extra_head，你需要把代码中的{% block head %}替换为这个官方指定的块。

修改后的代码示例：

sm/base.html 调整后

{% extends 'sm/bootstrap.html' %}

{% load django_bootstrap5 %}

{% block bootstrap5_extra_head %}
 <meta name="robots" content="all, index, follow" />
{% endblock %}

{% block bootstrap5_content %}
    <div class="container">
        <h1>{% block title %}(no title){% endblock %}</h1>
        {% autoescape off %}{% bootstrap_messages %}{% endautoescape %}
        {% block content %}(no content){% endblock %}
    </div>

{% endblock %}

sm/home.html 调整后

{% extends 'sm/base.html' %}
{% load django_bootstrap5 %}


{% block title %}My title{% endblock %}

{% block bootstrap5_extra_head %}
 <meta name="robots" content="all, index, follow" />
{% endblock %}

{% block content %}
    <br/>
    
{% endblock %}

修改完成后，robots元标签就会正确渲染到页面的head区域中。

内容的提问来源于stack exchange，提问作者Baz