Python的Flask开发框架简单上手笔记

概述最简单的helloworld#!/usr/bin/envpython#encoding:utf-8fromflaskimportFlaskapp=Flask(__name__)@app.route(\'/\')

最简单的hello world

#!/usr/bin/env python# enCoding: utf-8from flask import Flaskapp = Flask(__name__)@app.route('/')def index():  return 'hello world'if __name__ == '__main__':  app.run(deBUG=True)  #app.run(host='127.0.0.1',port=8000)

之后，访问http://localhost:5000

支持post/get提交

@app.route('/',methods=['GET','POST'])

多个url指向

@app.route('/')@app.route('/index')

不管post/get使用统一的接收

from flask import requestargs = request.args if request.method == 'GET' else request.forma = args.get('a','default')

处理Json请求
request的header中

"Content-Type": "application/Json"

处理时:

data = request.get_Json(silent=False)

获取post提交中的checkBox

{%for page in pages %}<tr><td><input type=checkBox name=do_delete value="{{ page['ID'] }}"></td><td>{%endfor%}page_IDs = request.form.getList("do_delete")

使用url中的参数

@app.route('/query/<qID>/')def query(qID):  pass

在request开始结束dosomething
一般可以处理数据库连接等等

from flask import gapp = .....@app.before_requestdef before_request():  g.session = create_session()@app.teardown_requestdef teardown_request(exception):  g.session.close()

注册Jinja2模板中使用的过滤器

@app.template_filter('reverse')def reverse_filter(s):  return s[::-1]

或者

def reverse_filter(s):  return s[::-1]app.jinja_env.filters['reverse'] = reverse_filter

可以这么用

def a():...def b():...FIL = {'a': a,'b':b}app.jinja_env.filters.update(FIL)

注册Jinja2模板中使用的全局变量

JINJA2_GLOBALS = {'MEDIA_PREFIX': '/media/'}app.jinja_env.globals.update(JINJA2_GLOBALS)

定义应用使用的template和static目录

app = Flask(__name__,template_folder=settings.TEMPLATE_FolDER,static_folder = settings.STATIC_PATH)

使用Blueprint

from flask import Blueprintbp_test = Blueprint('test',__name__)#bp_test = Blueprint('test',__name__,url_prefix='/abc')@bp_test.route('/')--------from xxx import bp_testapp = Flask(__name__)app.register_blueprint(bp_test)

实例:

bp_vIDeo = Blueprint('vIDeo',url_prefix='/kw_news/vIDeo')@bp_vIDeo.route('/search/category/',methods=['POST','GET'])#注意这种情况下Blueprint中url_prefix不能以 '/' 结尾,否则404

使用session
包装cookie实现的，没有session ID

app.secret_key = 'PS#yio`%_!((f_or(%)))s'

然后

from flask import sessionsession['somekey'] = 1session.pop('logged_in',None)session.clear()#过期时间,通过cookie实现的from datetime import timedeltasession.permanent = Trueapp.permanent_session_lifetime = timedelta(minutes=5)

反向路由

from flask import url_for,render_template@app.route("/")def home():  login_uri = url_for("login",next=url_for("home"))  return render_template("home.HTML",**locals())

上传文件

<form action="/image/upload/" method="post" enctype="multipart/form-data"><input type="file" name="upload" />

接收

f = request.files.get('upload')img_data = f.read()

直接返回某个文件

return send_file(settings.TEMPLATE_FolDER + 'tweet/tweet_List.HTML')

请求重定向

flask.redirect(location,code=302) the redirect status code. defaults to 302.Supported codes are 301,302,303,305,and 307. 300 is not supported.@app.route('/')def hello():  return redirect(url_for('foo'))@app.route('/foo')def foo():  return'Hello Foo!'

获取用户真实ip
从request.headers获取

real_ip = request.headers.get('X-Real-Ip',request.remote_addr)
或者,使用werkzeug的mIDdleware 文档

from werkzeug.contrib.fixers import ProxyFixapp.wsgi_app = ProxyFix(app.wsgi_app)return Json & Jsonpimport Jsonfrom flask import Jsonify,Response,Jsondata = [] # or othersreturn Jsonify(ok=True,data=data)Jsonp_callback = request.args.get('callback','')if Jsonp_callback:  return Response(      "%s(%s);" % (Jsonp_callback,Json.dumps({'ok': True,'data':data})),mimetype="text/JavaScript"      )return ok_Jsonify(data)

配置读取方法

# create our little application :)app = Flask(__name__)# Load default config and overrIDe config from an environment variableapp.config.update(dict(  DATABASE='/tmp/flaskr.db',DEBUG=True,SECRET_KEY='development key',USERname='admin',PASSWORD='default'))app.config.from_envvar('FLASKR_SETTINGS',silent=True)------------------# configurationDATABASE = '/tmp/minitwit.db'PER_PAGE = 30DEBUG = TrueSECRET_KEY = 'development key'# create our little application :)app = Flask(__name__)app.config.from_object(__name__)app.config.from_envvar('MINITWIT_SETTINGS',silent=True)

几个不常用的方法

from flask import abort,flashabortif not session.get('logged_in'):  abort(401)flashflash('New entry was successfully posted')

异步调用
想在flask的一个请求中处理异步,除了使用消息系统,可以用简单的线程处理

from threading import Threaddef async(f):  def wrapper(*args,**kwargs):    thr = Thread(target=f,args=args,kwargs=kwargs)    thr.start()  return wrapper@asyncdef dosomething(call_args):  print call_argsin a request handler,call `dosomething`error handler@app.errorhandler(404)def not_found_error(error):  return render_template('404.HTML'),404@app.errorhandler(500)def internal_error(error):  db.session.rollback()  return render_template('500.HTML'),500

项目配置
1.直接

app.config['HOST']='xxx.a.com'print app.config.get('HOST')

2.环境变量

export MyAppConfig=/path/to/settings.cfgapp.config.from_envvar('MyAppConfig')

3.对象

 class Config(object):   DEBUG = False   TESTING = False   DATABASE_URI = 'sqlite://:memory:' class ProductionConfig(Config):   DATABASE_URI = 'MysqL://user@localhost/foo' app.config.from_object(ProductionConfig) print app.config.get('DATABASE_URI') # MysqL://user@localhost/foo

4.文件

# default_config.pyHOST = 'localhost'PORT = 5000DEBUG = Trueapp.config.from_pyfile('default_config.py')

EG. 一个create_app方法

from flask import Flask,gdef create_app(deBUG=settings.DEBUG):  app = Flask(__name__,static_folder=settings.STATIC_FolDER)  app.register_blueprint(bp_test)  app.jinja_env.globals.update(JINJA2_GLOBALS)  app.jinja_env.filters.update(JINJA2_FILTERS)  app.secret_key = 'PO+_)(*&678OUIJKKO#%_!(((%)))'  @app.before_request  def before_request():    g.xxx = ...  #do some thing  @app.teardown_request  def teardown_request(exception):    g.xxx = ...  #do some thing  return appapp = create_app(settings.DEBUG)host=settings.SERVER_IPport=settings.SERVER_PORTapp.run(host=host,port=port)change log:2013-09-09 create2014-10-25 update

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