专题十四 Jinja2常用操作

Python高效编程技巧实战

常用标签

There are a few kinds of delimiters. The default Jinja delimiters are configured as follows

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

For

## Loop over each item in a sequence. For example, to display a list of users provided in a variable called users:
<h1>Members</h1>
<ul>
{% for user in users %}
  <li>{{ user.username|e }}</li>
{% endfor %}
</ul>
--------------------
## As variables in templates retain their object properties, it is possible to iterate over containers like dict:
<dl>
{% for key, value in my_dict.iteritems() %}
    <dt>{{ key|e }}</dt>
    <dd>{{ value|e }}</dd>
{% endfor %}
</dl>
{% for row in rows %}
    <li class="{{ loop.cycle('odd', 'even') }}">{{ row }}</li>
{% endfor %}
{% for user in users if not user.hidden %}
    <li>{{ user.username|e }}</li>
{% endfor %}
<ul>
{% for user in users %}
    <li>{{ user.username|e }}</li>
{% else %}
    <li><em>no users found</em></li>
{% endfor %}
</ul>
<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>

If

{% if users %}
<ul>
{% for user in users %}
    <li>{{ user.username|e }}</li>
{% endfor %}
</ul>
{% endif %}
## For multiple branches, elif and else can be used like in Python. You can use more complex Expressions there, too:
{% if kenny.sick %}
    Kenny is sick.
{% elif kenny.dead %}
    You killed Kenny!  You bastard!!!
{% else %}
    Kenny looks okay --- so far
{% endif %}

Assignments

{% set iterated = false %}
{% for item in seq %}
    {{ item }}
    {% set iterated = true %}
{% endfor %}
{% if not iterated %} did not iterate {% endif %}
It is not possible with Jinja syntax to do this. Instead use alternative constructs like the loop else block or the special loop variable:
{% for item in seq %}
    {{ item }}
{% else %}
    did not iterate
{% endfor %}

示例代码

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from jinja2 import Template
def render_str(str, data):
    template = Template(str)
    val = template.render(data)
    return val
with open('tpl01','r') as f:
    data = {
        'name' : 'zhangshuang'
    }
    content = f.read()
    print render_str(content, data)
## tpl01
My name is {{ name }}
## 运行结果
(/anaconda) work:jinja2 ys$ python demo01.py 
My name is zhangshuang
----------------------------------------
with open('tpl02','r') as f:
    data = {
        'user' : {
            'name': 'zhangshuang'
        },
        'age' : 27
    }
    content = f.read()
    print render_str(content, data)
## tpl02
name : {{ user.name }}
age : {{ age }}
## 运行结果
name : zhangshuang
age : 27
----------------------------------------
with open('tpl03','r') as f:
    data = {
        'user_num_start' : 1000,
        'user_list' : [
            {
                'name' : 'zhangshuang',
                'age' : 27
            },
            {
                'name' : 'zhangsan',
                'age' : 28
            },
            {
                'name' : 'lisi',
                'age' : 30
            },
            {
                'name': 'unknow',
                'age': 30
            }
        ]
    }
    content = f.read()
    print render_str(content, data)
## tpl03
{%- for item in user_list %}
    <li>name : {{ item.name }},age : {{ item.age }}</li>
{%- endfor %}
{%- for item in user_list -%}
    {% set user_num = loop.index + user_num_start %}
    {%- if item.name != 'unknow' %}
        <li>name : {{ item.name }}, age : {{ item.age }}, user_num : {{ user_num }}</li>
    {%- endif %}
{%- endfor -%}
## 运行结果
<li>name : zhangshuang,age : 27</li>
<li>name : zhangsan,age : 28</li>
<li>name : lisi,age : 30</li>
<li>name : unknow,age : 30</li>
<li>name : zhangshuang, age : 27, user_num : 1001</li>
<li>name : zhangsan, age : 28, user_num : 1002</li>
<li>name : lisi, age : 30, user_num : 1003</li>