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', __name__, 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__, template_folder=settings.TEMPLATE_FOLDER, 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