jinja2

由 datahunter 在三, 11/12/2013 - 14:38 發表

最後更新: 2015-09-09

介紹

Jinja is a fast, expressive, extensible templating engine.

sandboxed execution
powerful automatic HTML escaping system
template inheritance

Install jinja2

yum

yum install python-jinja2 # Centos 7

pip

pip install jinja2

pip install jinja2==2.11

* jinja2 depends on the MarkupSafe module

MarkupSafe 比 jinja 自帶的 Markup 行得怏, 建議使用它

Test it

test.py

from jinja2 import Template

template = Template('Hello {{name}}!')   # template 格式
msg = template.render(name='datahunter') # dict or keywords arguments
print msg                                # Hello datahunter!

python test.py

Variable in template

{{ a_variable }}

"." , [''] to access attributes of a variable

{{ foo.bar }} # 較短
{{ foo['bar'] }}

* If a variable or attribute does not exist you will get back an undefined value.

提取 data 時會有兩個情況

Value
Null # access variable undefined value
Error # access object undefined attribute

data.title # 拎 attr 時

<class 'jinja2.exceptions.UndefinedError'> at /

Jinja2 with webpy

hello.py

import web
from web.contrib.template import render_jinja

urls = (
    "/", "hello",
)

render = render_jinja(
    'templates',              # Set template directory.
    encoding = 'utf-8',       # Set html 檔的 Encoding(utf-8 ...)
)

app = web.application(urls, globals(), autoreload=True)

class hello:
    def GET(self):
        return render.hello(title='test msg')

if (__name__ == "__main__"):
    app.run()
else:
    application = app.wsgifunc()

templates/hello.html

<html>
    <head><title>{{name}}</title></head>
    <body>My title is {{name}}</body>
</html>

"with" Statement

with: create a new inner scop

{% with %}
    {% set foo = 42 %}
    {{ foo }}           foo is 42 here
{% endwith %}

# foo is not visible here any longer
{{ foo }}

Function

seq

{% set seq = [1,2,3] %}

Escaping

<1>

{{ '{{' }}

<2>

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

Filters

Variables can be modified by filters

{{ variable|filter }}
{{ variable|filter1|filter2 }}
{{ list|join(', ') }}

builtin-filters:

lower
center
forceescape
trim
truncate(length=255)
urlencode
wordwrap(width=79)
striptags # Strip SGML/XML tags and replace adjacent whitespace by one space.
join(', ')

Control Structures

for

<ul>
{% for user in users %}
  <li>{{ user.username|e }}</li>
{% endfor %}
</ul>

支援 continue, break

{% continue %}, {% break %}

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

special variables:

loop.index
loop.first
loop.last
loop.length

<1>

{% if pageinfo.saveLogin == "on" %}
    .........
{% endif %}

<2>

i.e. 1

{% if variable is defined %}
    value of variable: {{ variable }}
{% else %}
    variable is not defined
{% endif %}

i.e. 2

{% if loop.index is divisibleby 3 %}

Builtin Tests

divisibleby N
callable
defined, undefined
equalto
none
string, number
iterable
odd, even
upper, lower
mapping (dict)

i.e. 3

{% if kenny.sick %}
    Kenny is sick.
{% elif kenny.dead %}
    You killed Kenny!  You bastard!!!
{% else %}
    Kenny looks okay --- so far
{% endif %}

Whitespace Control

* Jinja2 by default 係會 keep whitespace (spaces, tabs) 及頭一行 newline 的

Example:

* 它們是有不同的

<!-- 1 -->
<div>
    {% if True %}
        yay
    {% endif %}
</div>

<!-- 2 -->
<div>
    {% if True %} 1 {% endif %}
    {% if True %} 2 {% endif %}
</div>

的 result 是

<!-- 1 -->
<div>
                 # 多了頭這一空行
        yay      # yay 前面有空格
                 # 多了尾這一空行
</div>

<!-- 2 -->
<div>
     1           # 一句 statment 係會佔用一行的
     2
</div>

(-) 移除了尾的 newline. "-" 在不同的角會有不同的意思)

ie.1

{% set seq = [1,2,3] %}
<div>
<!-- 不要頭空行 -->
{%- for item in seq %}         
    {{ item }}
{% endfor -%}
<!-- 不要尾空行 -->
</div>

result:

<div>
    1
    2
    3
</div>

ie.2 不要頭空行及空格

{% set seq = [1,2,3] %}
<div>
{% for item in seq -%}         
    {{ item }}
{% endfor %}
</div>

result:

<div>
1
2
3

</div>

ie.3 一行過

{% set seq = [1,2,3] %}
<div>
{% for item in seq -%}         
    {{ item }}
{%- endfor %}
</div>

Include

{% include 'header.html' %}
    Body
{% include 'footer.html' %}

Macros

macro code(file: forms.html)

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

use it(same file)

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

Import

* forms.html 裝了 macro 的 code

{% import 'forms.html' as forms %}

{{ forms.input('username') }}

Template Inheritance

Base Template - base.tmpl

用 "{% block NAME %}...{% endblock %}" 定義了 4 個 block

<html lang="en">
<head>
    {% block head %}
    <link rel="stylesheet" href="style.css" />
    <title>{% block title %}{% endblock %} - My Webpage</title>
    {% endblock %}
</head>
<body>
    <div id="content">{% block content %}{% endblock %}</div>
    <div id="footer">
        {% block footer %}
        &copy; Copyright 2008 by <a href="http://domain.invalid/">you</a>.
        {% endblock %}
    </div>
</body>

Child Template - child.tmpl

{% extends "base.tmpl" %}

{% block title %}Index{% endblock %}

{% block head %}
    {{ super() }}
    <style type="text/css">
        .important { color: #336699; }
    </style>
{% endblock %}

{% block content %}
    <h1>Index</h1>
    <p class="important">
      Welcome on my awesome homepage.
    </p>
{% endblock %}

同名的 macro

layout.tmpl:

{% macro foo() %}LAYOUT{% endmacro %}
{% block body %}{% endblock %}

child.tmpl:

{% extends 'layout.tmpl' %}
{% macro foo() %}CHILD{% endmacro %}
{% block body %}{{ foo() }}{% endblock %}

Result: LAYOUT !!

i18n

* wrapped string as translatable and calls gettext

template:

{{ _('Hello World!') }}

i18n\zh_TW\LC_MESSAGES

Doc

https://jinja.palletsprojects.com/en/2.11.x/

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