python基础===flask使用整理（转）

flask 使用的一些整理

资源

Flask 文档|英文| expore flask| 快速教材| flask-admin| Flask-DebugToolbar| Flask-Login| Flask-Cache|flask-sqlalchemy| flask-security| Flask-mako| Flask-Genshi| WTForms

Flask Extensions

---

最简单的hello world

Python

#!/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)

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#!/usr/bin/env python # encoding: utf-8   Flask )   ) : 'hello world'   : ) #app.run(host='127.0.0.1', port=8000)

之后，访问http://localhost:5000

支持post/get提交

Python

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

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多个url指向

Python

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

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) )

不管post/get使用统一的接收

Python

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

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request form )

处理json请求

request的header中

 

"Content-Type": "application/json"

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处理时:

Python

data = request.get_json(silent=False)

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)

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")

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} > }   )

使用url中的参数

 

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

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) : pass

在request开始结束dosomething

一般可以处理数据库连接等等

Python

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()

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g   .   before_request : )   teardown_request : )

注册Jinja2模板中使用的过滤器

Python

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

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) : ]

或者

Python

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

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: ] reverse_filter

可以这么用

Python

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

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. .   } )

注册Jinja2模板中使用的全局变量

Python

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

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} )

定义应用使用的template和static目录

Python

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

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使用Blueprint

Python

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)

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

实例:

Python

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

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) ) #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

Python

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)

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'PS#yio`%_!((f_or(%)))s'   # 然后 session   1 )   )   #过期时间,通过cookie实现的 timedelta True )

 

反向路由

Python

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())

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_template   ) : ) )

上传文件

 

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

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> >

接收

Python

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

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) )

直接返回某个文件

Python

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

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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.

Python

@app.route('/') def hello(): return redirect(url_for('foo')) @app.route('/foo') def foo(): return'Hello Foo!'

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) : )   ) : 'Hello Foo!'

获取用户真实ip

从request.headers获取

Python

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

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或者, 使用werkzeug的middleware 文档

Python

from werkzeug.contrib.fixers import ProxyFix app.wsgi_app = ProxyFix(app.wsgi_app)

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return json & jsonp

Python

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)

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json json   # or others )   ) : ( , ) )

 

配置读取方法

Python

# 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)

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# create our little application :) )   # Load default config and override config from an environment variable ( , , , , 'default' ) )   -- # configuration '/tmp/minitwit.db' 30 True 'development key'   # create our little application :) ) ) )

 

几个不常用的方法

Python

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

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flash   abort : )   flash )

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

Python

from threading import Thread def async(f): def wrapper(*args, **kwargs): thr = Thread(target=f, args=args, kwargs=kwargs) thr.start() return wrapper @async def dosomething(call_args): print call_args in a request handler, call `dosomething`

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Thread   : : ) ) wrapper   async : call_args   `

 

error handler

Python

@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

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) : 404   ) : ) 500

 

项目配置

1.直接

Python

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

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2.环境变量

Python

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

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cfg )

3.对象

Python

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

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: False False 'sqlite://:memory:'   : 'mysql://user@localhost/foo'   ) # mysql://user@localhost/foo

4.文件

Python

# default_config.py HOST = 'localhost' PORT = 5000 DEBUG = True app.config.from_pyfile('default_config.py')

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# default_config.py 'localhost' 5000 True   )

EG. 一个create_app方法

Python

from flask import Flask, g def 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 app app = create_app(settings.DEBUG) host=settings.SERVER_IP port=settings.SERVER_PORT app.run(host=host, port=port)

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g   : , , )   )   ) )   'PO+_)(*&678OUIJKKO#%_!(((%)))'   before_request : #do some thing   teardown_request : #do some thing   app   ) SERVER_IP SERVER_PORT )