Flask 通关攻略大全

基本使用

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello World!'

if __name__ == '__main__':
    app.run()

配置文件

在app 中引入

app.config.from_object("settings.DevelopmentConfig")

settings

class BaseConfig(object):
    DEBUG = True
    SECRET_KEY = "随机字符串"

class ProductionConfig(BaseConfig):
    DEBUG = False

class DevelopmentConfig(BaseConfig):
    pass

class TestingConfig(BaseConfig):
    pass

路由

a. 添加路由的两种方式：
	from flask import Flask,render_template,redirect
	app = Flask(__name__)

	"""
	1. 执行decorator=app.route('/index',methods=['GET','POST'])
	2. @decorator
		 - decorator(index)
	"""
	# 路由方式一（*）：
	@app.route('/index',methods=['GET','POST'])
	def index():
		return "Index"

	# 路由方式二：
	def order():
		return 'Order'

	app.add_url_rule('/order',view_func=order)

	if __name__ == '__main__':
		app.run()
b. endpoint(默认函数名)
c. 传参数
	@app.route('/index/<int:nid>',methods=['GET','POST'])
	def index(nid):
		print(nid,type(nid))

		url_for('index',nid=888)

		return "Index"
d. 自定义正则参数

		from flask import Flask,render_template,redirect,url_for
		from werkzeug.routing import BaseConverter
		app = Flask(__name__)

		class RegexConverter(BaseConverter):
			"""
			自定义URL匹配正则表达式
			"""
			def __init__(self, map, regex):
				super(RegexConverter, self).__init__(map)
				self.regex = regex

			def to_python(self, value):
				"""
				路由匹配时，匹配成功后传递给视图函数中参数的值
				:param value:
				:return:
				"""
				return int(value)

			def to_url(self, value):
				"""
				使用url_for反向生成URL时，传递的参数经过该方法处理，返回的值用于生成URL中的参数
				:param value:
				:return:
				"""
				val = super(RegexConverter, self).to_url(value)
				return val

		app.url_map.converters['xxx'] = RegexConverter

		@app.route('/index/<xxx("\d+"):nid>',methods=['GET','POST'])
		def index(nid):
			print(nid,type(nid))
			v = url_for('index',nid=999) # /index/999
			print(v)
			return "Index"

		if __name__ == '__main__':
			app.run()

e. 其他参数
	- 重定向
		from flask import Flask,render_template,redirect
		app = Flask(__name__)

		@app.route('/index',methods=['GET','POST'],redirect_to='/new')
		def index():
			return "老功能"

		@app.route('/new',methods=['GET','POST'])
		def new():
			return '新功能'

		if __name__ == '__main__':
			app.run()

		PS: 前端重定向
			- meta/js

重点：
	- url
	- methods
	- endpoint
	- @app.route('/index/<int:nid1>/<int:nid2>/')
	- url_for

视图函数

fbv(常用)

import functools

def wapper(func):
    @functools.wraps(func)
    def inner(*args,**kwargs):
        print('before')
        return func(*args,**kwargs)
    return inner

@app.route('/xxxx',methods=['GET','POST'])
@wapper
def index():
    return "Index"

cbv

class IndexView(views.MethodView):
    methods = ['GET']
    decorators = [wapper, ]

    def get(self):
        return 'Index.GET'

    def post(self):
        return 'Index.POST'

app.add_url_rule('/index', view_func=IndexView.as_view(name='index2'))  # name=endpoint

请求和响应

请求相关

request.method
request.args
request.form
request.cookies
request.headers
request.path
request.files

obj = request.files['the_file_name']
obj.save('/var/www/uploads/' + secure_filename(obj.filename))

request.values
request.full_path
request.script_root
request.url
request.base_url
request.url_root
request.host_url
request.host

响应相关

return ""
return json.dumps({}) # return jsonify({})
return render_template('index.html',n1=123)
return redirect('/index')

response = make_response(render_template('index.html'))
response = make_response("xxxx")
response.set_cookie('key', 'value')
response.headers['X-Something'] = 'A value'
response.delete_cookie('key')
return response

模板

调用方法基本和Django相同

session

• 设置：session['username'] ＝ 'xxx'
• 删除：session.pop('username', None)
  
  

蓝图(Blueprint)

目录结构



manage.py

from s8pro import app

if __name__ == '__main__':
    app.run()

init.py

from flask import Flask
from .views import account
from .views import admin
from .views import user

app = Flask(__name__)

app.register_blueprint(account.ac)
app.register_blueprint(admin.ad)
app.register_blueprint(user.us)

views 文件夹内

1.account.py

from flask import Blueprint,render_template
import redis

ac = Blueprint('ac',__name__)

@ac.route('/login')
def login():
    conn = redis.Redis()
    return render_template('login.html')

@ac.route('/logout')
def logout():
    return '退出'

2.admin.py

from flask import Blueprint

ad = Blueprint('ad',__name__,url_prefix='/admin')

@ad.before_request
def bf():
    print('before_request')

@ad.route('/home')
def home():
    return 'home'

@ad.route('/xxxx')
def xxxx():
    return 'xxxx'

3.user.py

from flask import Blueprint

us = Blueprint('us',__name__)

@us.route('/info')
def info():
    return 'info'

前缀和子域名

蓝图URL前缀：xxx = Blueprint('account', __name__,url_prefix='/xxx')
蓝图子域名：xxx = Blueprint('account', __name__,subdomain='admin')
    # 前提需要给配置SERVER_NAME： app.config['SERVER_NAME'] = 'xxx.com:5000'
    # 访问时：admin.xxx.com:5000/login.html

闪现(message)

message是一个基于Session实现的用于保存数据的集合
其特点是：使用一次就删除。
@app.route('/x1',methods=['GET','POST'])
def login():
    flash('我要上学校1',category='x1')
    flash('我要上学校2',category='x2')
    return "视图函数x1"

@app.route('/x2',methods=['GET','POST'])
def index():
    data = get_flashed_messages(category_filter=['x1'])
    print(data)
    return "视图函数x2"

中间件

class Middleware(object):
    def __init__(self,old_wsgi_app):
        """
        服务端启动时，自动执行
        :param old_wsgi_app:
        """
        self.old_wsgi_app =old_wsgi_app

    def __call__(self, environ, start_response):
        """
        每次有用户请求道来时
        :param args:
        :param kwargs:
        :return:
        """
        print('before')
        from flask import session,request
        obj = self.old_wsgi_app(environ, start_response)
        print('after')
        return obj

if __name__ == '__main__':
    app.wsgi_app = Middleware(app.wsgi_app)
    app.run()
    """
    1.执行app.__call__
    2.再调用app.wsgi_app方法
    """

常见装饰器

@app.before_request         每次请求进来之前执行
@app.after_request          每次请求进来之后执行
@app.errorhandler(404)      引发404错误时候执行
@app.before_first_request   第一次请求进来之前执行（如创建数据库连接池这样的业务）
@app.template_global()      调用方法{{函数名(参数1，参数2)}}
@app.template_filter()      调用方法{{参数1|函数名(参数2，参数3))}}