Tornado templates模板渲染語法總結
工作需要研究了一下tornado的模板渲染語法，寫了個測試，總結了一下相關語法，聊作筆記如下。
tornado本身非常靈活，支持幾乎所有python支持的模板語言。除此之外，它本身也提供了一個輕量級的模板，放在tornado.template中。
測試用例
代碼清單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()
代碼清單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="checkbox" {{checked(item)}} /> {{item}}</li>
{% end %}
{{ add(2,2) }}
</ul>
</body>
</html>
在同一文件夾中創建如上兩個文件，然後在命令行運行python
tornado_temp_test.py，再在瀏覽器打開localhost:8081，可以看到如下界面：
查看改網頁的源代碼爲：
<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>
測試用例解釋
- 在程序中，我們通過語句
self.render("template_test.html", items=items, add=add, items2=items2, checked=checked)來渲染模板，其中render的第一個參數爲模板文件，後面的所有參數會被傳入模板文件中。此處可以將其他所有參數放入一個參數中，然後用參數解析語法**kwargs來傳入。如此處的調用等價於：kwargs = { 'items': items, 'items2': items2, 'add':add, 'checked':checked } self.render("template_test.html", **kwargs) - 渲染函數將模板中的相關語法進行解析，將動態生成的數據插入其中，生成了新的頁面，展示出來就成了上圖看到的樣子。此處用到的語法包括：
{% for item in items %} ... {% end %}：相當於python中的for語句。{{ add(2,2) }}執行了python中的add(2, 2)，將結果放在此處，即圖中我們看到的4。{{checked(item)}}同理。value={{item}}將循環中產生的item賦給value，查看網頁源代碼可知<input value={{item}} name={{item}} type="checkbox" {{checked(item)}} />被解析成了<input value="item1" name="item1" type="checkbox" checked="checked"/>
模板語法彙總（來自官方文檔）
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
{{ or
{% 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.
參考鏈接：
【1】：template@tornado 學習記錄
【2】：Introduction to Tornado中文版相關內容
【3】：官方文檔中的相關內容