The example code from the official jinja site:
{% if not standalone %}{% extends 'master.html' %}{% endif -%}
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<title>{% block title %}The Page Title{% endblock %}</title>
<link rel="stylesheet" href="style.css" type="text/css">
{% block body %}
<p>This is the page body.</p>
{% endblock %}
As I understand it, when standalone is true the following code is printed :
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<title>{% block title %}The Page Title{% endblock %}</title>
<link rel="stylesheet" href="style.css" type="text/css">
{% block body %}
<p>This is the page body.</p>
{% endblock %}
And when standalone is false, this is printed :
{% if not standalone %}
<<master.html's code>>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<title>{% block title %}The Page Title{% endblock %}</title>
<link rel="stylesheet" href="style.css" type="text/css">
{% block body %}
<p>This is the page body.</p>
{% endblock %}
This seems is very weird. I am clearly missing something obvious, what is it ?
The thing that is not immediately clear from the documentation is that when a template extends another template only the blocks in the child template that have a counterpart in the parent template(s) are rendered. Everything else is dropped.
So in non-standalone mode: