**Flask之Hello world 详解
========================**
以下讲解假设你对python有基本了解,熟悉wsgi,以及了解某种python web framework.
from flask import Flask
app = Flask(__name__)@app.route('/')
def hello_world():return "HELLO WROLD"if __name__ == '__main__':app.run(debug=True)
- Flask的实例app就是我们的WSGI application.
- 创建Flask实例需要指定一个参数,这个参数一般是application的模块名字或者是包名.Flask根据这个参数定位templates,static files等.
- route装饰器告诉Flask什么样的请求路径对应这个函数
####Routing
route()装饰器支持变量规则,用<variable_name>表示.还可以制订一个转换器.例如:
@app.route('/user/<username>')
def show_user_profile(username):# show the user profile for that userreturn 'User %s' % username@app.route('/post/<int:post_id>')
def show_post(post_id):# show the post with the given id, the id is an integerreturn 'Post %d' % post_id@app.route('/user/<path:location>')
def show_path(location):return location
有三种转换器:
int accepts integers
float like int but for floating point values
path like the default but also accepts slashes
####HTTP METHOD
from flask import request@app.route('/login', methods=['GET', 'POST'])
def login():if request.method == "POST":return 'post'else:return 'get'
####Static Files
在package或则module同目录下创建static目录
url_for('static', filename='style.css')
####rendering templates
默认Flask配置JinJia2作为模板引擎,因为他们是一家的.Flask会在templates目录下查找模板文件,如果application是一个module,那么这个templates目录与application同级目录.如果他是一个package:
-
case 1: a module:
/application.py
/templates
/hello.html -
case 2: a application
/application
/init.py
/templates
/hello.html
渲染模板使用render_template()
from flask import render_template
@app.route('/hello/')
@app.route('/hello/<name>')
def hello(name=None):return render_template('hello.html',name=name)
JinJia2 模板的语法和Mako以及django的语法都差不多,可以稍作了解
<!doctype html>
<title>Hello from Flask</title>
{% if name %}<h1>Hello {{ name }}!</h1>
{% else %}<h1>Hello World!</h1>
{% endif %}
####Context locals
先跳过