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Tornado templates模板渲染语法总结

2014-10-21 17:03 288 查看

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Tornado templates模板渲染语法总结

工作需要研究了一下tornado的模板渲染语法，写了个测试，总结了一下相关语法，聊作笔记如下。

tornado本身非常灵活，支持几乎所有python支持的模板语言。除此之外，它本身也提供了一个轻量级的模板，放在

tornado.template

中。

测试用例

代码清单1：

tornado_template.py

import tornado.httpserver
import tornado.ioloop
import tornado.web

# define one "add" customization funcation which will be used in the assigned template file.
def add(x, y):
return (x+y)

class MainHandler(tornado.web.RequestHandler):
def get(self):
items = ["item1","item2","item3"]
# render the corresponding template file, and pass the "**args" to the assigned template
# not only we can pass the realted parameters, but also can pass the related functions.
# so extendible and powerful! :)
items2 = ["item1", "item2"]
def checked(item):
return 'checked=checked' if item in items2 else ''
self.render("template_test.html", items=items, add=add, items2=items2, checked=checked)

application = tornado.web.Application([
(r"/", MainHandler),
])

if __name__ == "__main__":
http_server = tornado.httpserver.HTTPServer(application)
http_server.listen(8081)
tornado.ioloop.IOLoop.instance().start()

代码清单2：

template_test.html

<html>
<head>
<title>template function test</title>
</head>
<body>
<ul>
{% for item in items %}
<li>{{ escape(item) }}</li>
<li> <input  value={{item}} name={{item}}  type="checkbo
11da1
x" {{checked(item)}} /> {{item}}</li>
{% end %}

{{ add(2,2) }}
</ul>
</body>
</html>

在同一文件夹中创建如上两个文件，然后在命令行运行

python
tornado_temp_test.py

，再在浏览器打开

localhost:8081

，可以看到如下界面：

查看改网页的源代码为：

<html>
<head>
<title>template function test</title>
</head>
<body>
<ul>

<li>item1</li>
<li> <input value=item1 name=item1 type="checkbox" checked=checked /> item1</li>

<li>item2</li>
<li> <input value=item2 name=item2 type="checkbox" checked=checked /> item2</li>

<li>item3</li>
<li> <input value=item3 name=item3 type="checkbox"  /> item3</li>

4
</ul>
</body>
</html>

测试用例解释

在程序中，我们通过语句

self.render("template_test.html",
items=items, add=add, items2=items2, checked=checked)

来渲染模板，其中

render

的第一个参数为模板文件，后面的所有参数会被传入模板文件中。此处可以将其他所有参数放入一个参数中，然后用参数解析语法

**kwargs

来传入。如此处的调用等价于：

kwargs = {
'items': items,
'items2': items2,
'add':add,
'checked':checked
}
self.render("template_test.html", **kwargs)

渲染函数将模板中的相关语法进行解析，将动态生成的数据插入其中，生成了新的页面，展示出来就成了上图看到的样子。此处用到的语法包括：

{%
for item in items %} ... {% end %}

：相当于python中的

for

语句。

{{
add(2,2) }}

执行了python中的

add(2,
2)

，将结果放在此处，即图中我们看到的

。

{{checked(item)}}

同理。

value={{item}}

将循环中产生的

item

赋给value，查看网页源代码可知

<input
value={{item}} name={{item}} type="checkbox" {{checked(item)}} />

被解析成了

<input
value="item1" name="item1" type="checkbox" checked="checked"/>

模板语法汇总（来自官方文档）

Template expressions are surrounded by double curly braces:

{{ ... }}

. The contents may be any python expression, which will be escaped according to the current autoescape setting and inserted into the output. Other template directives use

{% %}

. These tags may be escaped as

{{!

and

{%!

if you need to include a literal

{{

{%

in the output.

To comment out a section so that it is omitted from the output, surround it with

{# ... #}

{% apply *function* %}...{%
end %}

Applies a function to the output of all template code between apply and end:

{% apply linkify %}{{name}} said: {{message}}{% end %}

{% autoescape *function* %}

Sets the autoescape mode for the current file. This does not affect other files, even those referenced by

{% include %}

. Note that autoescaping can also be configured globally, at the Application or Loader.:

{% autoescape xhtml_escape %}{% autoescape None %}

{% block *name* %}...{% end
%}

Indicates a named, replaceable block for use with {% extends %}. Blocks in the parent template will be replaced with the contents of the same-named block in a child template.:

<!-- base.html -->
<title>{% block title %}Default title{% end %}</title>

<!-- mypage.html -->
{% extends "base.html" %}{% block title %}My page title{% end %}

{% comment ... %}

A comment which will be removed from the template output. Note that there is no {% end %} tag; the comment goes from the word comment to the closing %} tag.

{% extends *filename* %}

Inherit from another template. Templates that use extends should contain one or more block tags to replace content from the parent template. Anything in the child template not contained in a block tag will be ignored. For an example, see the {% block %} tag.

{% for *var* in *expr* %}...{%
end %}

Same as the python for statement.

{% from *x* import *y* %}

Same as the python import statement.

{% if *condition* %}...{% elif
*condition* %}...{% else %}...{% end %}

Conditional statement - outputs the first section whose condition is true. (The elif and else sections are optional)

{% import *module* %}

Same as the python import statement.

{% include *filename* %}

Includes another template file. The included file can see all the local variables as if it were copied directly to the point of the include directive (the

{% autoescape %}

directive is an exception). Alternately,

{% module Template(filename, **kwargs) %}

may be used to include another template with an isolated namespace.

{% module *expr* %}

Renders a UIModule. The output of the UIModule is not escaped:

{% module Template("foo.html", arg=42) %}

{% raw *expr* %}

Outputs the result of the given expression without autoescaping.

{% set *x* = *y* %}

Sets a local variable.

{% try %}...{% except %}...{%
finally %}...{% else %}...{% end %}

Same as the python try statement.

{% while *condition* %}...{% end %}

Same as the python while statement.

参考链接：

【1】：template@tornado 学习记录

【2】：Introduction to Tornado中文版相关内容

【3】：官方文档中的相关内容

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标签： templates python tornado 模板

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Tornado templates模板渲染语法总结