jinja2语法 - 悦读

官方文档
本文只是官方文档的部分摘录，只记录了常用语法，和python非常类似，方便快速理解使用
语法

{% ... %} for Statements
{{ ... }} for Expressions to print to the template output
{# ... #} for Comments not included in the template output
#  ... ## for Line Statements

获得属性

{{ foo.bar }}
{{ foo['bar'] }}

去掉空白字符

{% for item in seq -%}
    {{ item }}
{%- endfor %}

escaping，手动逃逸，自动逃逸会有性能问题

{{ user.username|e }}

输出大括号，裸语句块

{{‘{}’}} 
{% raw %}
    <ul>
    {% for item in seq %}
        <li>{{ item }}</li>
    {% endfor %}
    </ul>
{% endraw %}

Line Statements，需要在在environment中配置line_statement_prefix

# for item in seq:
    <li>{{ item }}</li>     ## this comment is ignored
# endfor

Inheritance

<title>{% block title %}{% endblock title %} - My Webpage</title>

{% extends "base.html" %}
{% block title %}Index{% endblock title %}

父模板block提供站位符，子模板block提供数据覆盖
super()可以获得父模板中的数据
endblock title可省略title

for

{% for row in rows %}
    <li class="{{ loop.cycle('odd', 'even') }}">{{ row }}</li>
{% endfor %}

loop.index
loop.index0
loop.reindex
loop.reindex0
loop.first
loop.last
loop.length
loop.cycle
loop.depth
loop.depth0
loop.previtem
loop.nextitem

else，iteration为空，执行else

<ul>
{% for user in users %}
    <li>{{ user.username|e }}</li>
{% else %}
    <li><em>no users found</em></li>
{% endfor %}
</ul>

for if

{% for user in users if not user.hidden %}
    <li>{{ user.username|e }}</li>
{% endfor %}

递归 for

<ul class="sitemap">
{%- for item in sitemap recursive %}
    <li><a href="{{ item.href|e }}">{{ item.title }}</a>
    {%- if item.children -%}
        <ul class="submenu">{{ loop(item.children) }}</ul>
    {%- endif %}</li>
{%- endfor %}
</ul>

Loop Controls

{% for user in users %}
    {%- if loop.index is even %}{% continue %}{% endif %}
    ...
{% endfor %}
{% for user in users %}
    {%- if loop.index >= 10 %}{% break %}{% endif %}
{%- endfor %}

if Expression，三元表达式

{% extends layout_template if layout_template is defined else 'master.html' %}

模板中的函数macro

{% macro input(name, value='', type='text', size=20) -%}
    <input type="{{ type }}" name="{{ name }}" value="{{
        value|e }}" size="{{ size }}">
{%- endmacro %}

<p>{{ input('username') }}</p>
<p>{{ input('password', type='password') }}</p>

块和宏参见(http://www.ttlsa.com/python/flask-jinja2-template-engine-block-and-macro/)

import，导入namespace

{% import 'forms.html' as forms %}
{% from 'forms.html' import input as input_field, textarea %}

Filter，块级别使用Filter

{% filter upper %}
    This text becomes uppercase
{% endfilter %}

Assignments，赋值

{% set key, value = call_something() %}

Include 直接导入模板

{% include "sidebar.html" ignore missing %}

Builtin Filters
List of Builtin Tests
List of Global Functions
参见(http://jinja.pocoo.org/docs/2.10/templates/#list-of-builtin-filters)

With Statement 上下文

{% with %}
    {% set foo = 42 %}
    {{ foo }}           foo is 42 here
{% endwith %}
foo is not visible here any longer

i18n，国际化

{% trans book_title=book.title, author=author.name %}
This is {{ book_title }} by {{ author }}
{% endtrans %}