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1、安装
pip3 install flask
2、特点
-
短小精悍、可扩展强 的一个Web框架。
- 注意：上下文管理机制
-
依赖wsgi：werkzurg
-
werkzurg：
示例一：
from werkzeug.wrappers import Request, Response
from werkzeug.serving import run_simple
def run(environ,start_response):
return [b"asdfasdf"]
if __name__ == '__main__':
run_simple('localhost', 4000, run)
示例二：
from werkzeug.wrappers import Request, Response
@Request.application
def hello(request):
return Response('Hello World!')
if __name__ == '__main__':
from werkzeug.serving import run_simple
run_simple('localhost', 4000, hello)
from flask import Flask
app = Flask(__name__)
@app.route('/index')
def index():
return "Hello World"
if __name__='__main__':
app.run()
3. 配置文件
app.config.from_object("settings.DevelopmentConfig")
class Config(object):
DEBUG = False
TESTING = False
DATABASE_URI = 'sqlite://:memory:'
class ProductionConfig(Config):
DATABASE_URI = 'mysql://user@localhost/foo'
class DevelopmentConfig(Config):
DEBUG = True
class TestingConfig(Config):
TESTING = True
4. 路由系统
- endpoint,反向生成URL，默认函数名
- url_for(‘endpoint’) / url_for(“index”,nid=777)
- 动态路由：
@app.route('/index/<int:nid>',methods=['GET','POST'])
def index(nid):
print(nid)
return "Index"
6. 请求相关
# 请求相关信息
# request.method
# request.args
# request.form
# request.values
# request.cookies
# request.headers
# request.path
# request.full_path
# request.script_root
# request.url
# request.base_url
# request.url_root
# request.host_url
# request.host
# request.files
# obj = request.files['the_file_name']
# obj.save('/var/www/uploads/' + secure_filename(f.filename))
7. 响应：
响应体：
return “asdf”
return jsonify({'k1':'v1'})
return render_template('xxx.html')
return redirect()
定制响应头：
obj = make_response("asdf")
obj.headers['xxxxxxx'] = '123'
obj.set_cookie('key', 'value')
return obj
render_template('index.html',stu_dic=STUDENT_DICT)
版本二：
import functools
def auth(func):
@functools.wraps(func)
def inner(*args,**kwargs):
if not session.get('user'):
return redirect(url_for('login'))
ret = func(*args,**kwargs)
return ret
return inner
@app.route('/index')
@auth
def index():
return render_template('index.html',stu_dic=STUDENT_DICT)
应用场景：比较少的函数中需要额外添加功能。
版本三：before_request
@app.before_request
def xxxxxx():
if request.path == '/login':
return None
if session.get('user'):
return None
return redirect('/login')
7. 模板渲染
- 基本数据类型：可以执行python语法，如：dict.get() list[‘xx’]
- 传入函数
- django，自动执行
- flask，不自动执行
- 全局定义函数
@app.template_global()
def sb(a1, a2):
# {{sb(1,9)}}
return a1 + a2
@app.template_filter()
def db(a1, a2, a3):
# {{ 1|db(2,3) }}
return a1 + a2 + a3
- 模板继承layout.html
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<title>Title</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body>
<h1>模板</h1>
{% block content %}{% endblock %}
</body>
</html>
tpl.html
{% extends "layout.html"%}
{% block content %}
{{users.0}}
{% endblock %}
- include
{% include "form.html" %}
form.html
<form>
asdfasdf
asdfasdf
asdf
asdf
</form>
- 宏
{% macro ccccc(name, type='text', value='') %}
<h1>宏</h1>
<input type="{{ type }}" name="{{ name }}" value="{{ value }}">
<input type="submit" value="提交">
{% endmacro %}
{{ ccccc('n1') }}
{{ ccccc('n2') }}
- 安全
- 前端： {{u|safe}}
- 前端： MarkUp(“asdf”)
8. session
当请求刚到来：flask读取cookie中session对应的值：eyJrMiI6NDU2LCJ1c2VyIjoib2xkYm95，将该值解密并反序列化成字典，放入内存以便视图函数使用。
视图函数：
@app.route('/ses')
def ses():
session['k1'] = 123
session['k2'] = 456
del session['k1']
return "Session"
session['xxx'] = 123
session['xxx']
当请求结束时，flask会读取内存中字典的值，进行序列化+加密，写入到用户cookie中。
9. 闪现，在session中存储一个数据，读取时通过pop将数据移除。
from flask import Flask,flash,get_flashed_messages
@app.route('/page1')
def page1():
flash('临时数据存储','error')
flash('sdfsdf234234','error')
flash('adasdfasdf','info')
return "Session"
@app.route('/page2')
def page2():
print(get_flashed_messages(category_filter=['error']))
return "Session"
10. 中间件
- call方法什么时候出发？
- 用户发起请求时，才执行。
- 任务：在执行call方法之前，做一个操作，call方法执行之后做一个操作。
class Middleware(object):
def __init__(self,old):
self.old = old
def __call__(self, *args, **kwargs):
ret = self.old(*args, **kwargs)
return ret
if __name__ == '__main__':
app.wsgi_app = Middleware(app.wsgi_app)
app.run()
11. 特殊装饰器
1. before_request
2. after_request
示例：
from flask import Flask
app = Flask(__name__)
@app.before_request
def x1():
print('before:x1')
return '滚'
@app.before_request
def xx1():
print('before:xx1')
@app.after_request
def x2(response):
print('after:x2')
return response
@app.after_request
def xx2(response):
print('after:xx2')
return response
@app.route('/index')
def index():
print('index')
return "Index"
@app.route('/order')
def order():
print('order')
return "order"
if __name__ == '__main__':
app.run()
3. before_first_request
from flask import Flask
app = Flask(__name__)
@app.before_first_request
def x1():
print('123123')
@app.route('/index')
def index():
print('index')
return "Index"
@app.route('/order')
def order():
print('order')
return "order"
if __name__ == '__main__':
app.run()
4. template_global
5. template_filter
6. errorhandler
@app.errorhandler(404)
def not_found(arg):
print(arg)
return "没找到"