flask

flask 使用的一些整理

资源

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Flask Extensions

---

最简单的hello world

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#!/usr/bin/env python

# encoding: utf-8

 

from flask import Flask

app = 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

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

多个url指向

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@app.route('/')

@app.route('/index')

不管post/get使用统一的接收

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fromflaskimportrequest

args=request.argsifrequest.method=='GET'elserequest.form

a=args.get('a','default')

处理json请求

request的header中

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"Content-Type": "application/json"

处理时:

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data=request.get_json(silent=False)

获取post提交中的checkbox

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{%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

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@app.route('/query/<qid>/')

defquery(qid):

    pass

在request开始结束dosomething

一般可以处理数据库连接等等

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from flask import g

 

app = .....

 

@app.before_request

def before_request():

    g.session = create_session()

 

@app.teardown_request

def teardown_request(exception):

    g.session.close()

注册Jinja2模板中使用的过滤器

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@app.template_filter('reverse')

defreverse_filter(s):

    returns[::-1]

或者

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def reverse_filter(s):

    return s[::-1]

app.jinja_env.filters['reverse'] = reverse_filter

可以这么用

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defa():...

defb():...

 

FIL={'a':a,'b':b}

app.jinja_env.filters.update(FIL)

注册Jinja2模板中使用的全局变量

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JINJA2_GLOBALS = {'MEDIA_PREFIX': '/media/'}

app.jinja_env.globals.update(JINJA2_GLOBALS)

定义应用使用的template和static目录

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

使用Blueprint

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from flask import Blueprint

bp_test = Blueprint('test', __name__)

#bp_test = Blueprint('test', __name__, url_prefix='/abc')

 

@bp_test.route('/')

 

--------

from xxx import bp_test

 

app = Flask(__name__)

app.register_blueprint(bp_test)

实例:

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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

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

 

# 然后

from flask import session

 

session['somekey'] = 1

session.pop('logged_in', None)

 

session.clear()

 

#过期时间,通过cookie实现的

from datetime import timedelta

session.permanent = True

app.permanent_session_lifetime = timedelta(minutes=5)

 

反向路由

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fromflaskimporturl_for,render_template

 

@app.route("/")

defhome():

    login_uri=url_for("login",next=url_for("home"))

    returnrender_template("home.html",**locals())

上传文件

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<form action="/image/upload/" method="post" enctype="multipart/form-data">

<input type="file" name="upload" />

接收

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

img_data=f.read()

直接返回某个文件

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return send_file(settings.TEMPLATE_FOLDER + 'tweet/tweet_list.html')

请求重定向

文档

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.

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@app.route('/')

defhello():

    returnredirect(url_for('foo'))

 

@app.route('/foo')

deffoo():

    return'Hello Foo!'

获取用户真实ip

从request.headers获取

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real_ip = request.headers.get('X-Real-Ip', request.remote_addr)

或者, 使用werkzeug的middleware 文档

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fromwerkzeug.contrib.fixersimportProxyFix

app.wsgi_app=ProxyFix(app.wsgi_app)

 

return json & jsonp

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import json

from flask import jsonify, Response, json

 

data = [] # or others

return 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

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# create our little application :)

app=Flask(__name__)

 

# Load default config and override config from an environment variable

app.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)

 

------------------

# configuration

DATABASE='/tmp/minitwit.db'

PER_PAGE=30

DEBUG=True

SECRET_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

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from flask import abort, flash

 

abort

if not session.get('logged_in'):

    abort(401)

 

flash

flash('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

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fromthreadingimportThread

 

defasync(f):

    defwrapper(*args,**kwargs):

        thr=Thread(target=f,args=args,kwargs=kwargs)

        thr.start()

    returnwrapper

 

@async

defdosomething(call_args):

    printcall_args

 

inarequesthandler,call`dosomething`

 

error handler

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@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

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app.config['HOST']='xxx.a.com'

printapp.config.get('HOST')

2.环境变量

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export MyAppConfig=/path/to/settings.cfg

app.config.from_envvar('MyAppConfig')

3.对象

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classConfig(object):

    DEBUG=False

    TESTING=False

    DATABASE_URI='sqlite://:memory:'

 

classProductionConfig(Config):

    DATABASE_URI='mysql://user@localhost/foo'

 

app.config.from_object(ProductionConfig)

printapp.config.get('DATABASE_URI')# mysql://user@localhost/foo

4.文件

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# default_config.py

HOST = 'localhost'

PORT = 5000

DEBUG = True

 

app.config.from_pyfile('default_config.py')

EG. 一个create_app方法

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fromflaskimportFlask,g

 

defcreate_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

    defbefore_request():

        g.xxx=...    #do some thing

 

    @app.teardown_request

    defteardown_request(exception):

        g.xxx=...    #do some thing

 

    returnapp

 

app=create_app(settings.DEBUG)

host=settings.SERVER_IP

port=settings.SERVER_PORT

app.run(host=host,port=port)