Python的Flask开发框架简单上手笔记_Python

最简单的hello world

									#!/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

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

多个url指向

1 2	`@app.route('/')` `@app.route('/index')`

不管post/get使用统一的接收

									from flask import request

									args = request.args if request.method == 'GET' else request.form

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

处理json请求
request的header中

1	`"Content-Type":` `"application/json"`

处理时:

1	`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 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

									@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

1 2	`JINJA2_GLOBALS` `=` `{'MEDIA_PREFIX':` `'/media/'}` `app.jinja_env.globals.update(JINJA2_GLOBALS)`

定义应用使用的template和static目录

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

使用Blueprint

									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:

									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

1	`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

									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

1 2	`<form action="/image/upload/"` `method="post"` `enctype="multipart/form-data">` `<input` `type="file"` `name="upload"` `/>`

接收

1 2	`f` `=` `request.files.get('upload')` `img_data` `=` `f.read()`

直接返回某个文件

1	`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 ProxyFix

									app.wsgi_app = ProxyFix(app.wsgi_app)

									return json & jsonp

									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

									# 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

									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

									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`

									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

1 2	`app.config['HOST']='xxx.a.com'` `print` `app.config.get('HOST')`

2.环境变量

1 2	`export MyAppConfig=/path/to/settings.cfg` `app.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.py

									HOST = 'localhost'

									PORT = 5000

									DEBUG = True

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

EG. 一个create_app方法

									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)

									change log:

									2013-09-09 create

									2014-10-25 update