flask开发小结
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)
支持post/get提交
:::python @app.route('/', methods=['GET', 'POST'])
多个url指向
:::python @app.route('/') @app.route('/index')
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')
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
:::python @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
:::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()
注册Jinja2模板中使用的过滤器
:::python @app.template_filter('reverse') def reverse_filter(s): return s[::-1]
或者
:::python def reverse_filter(s): return s[::-1] app.jinja_env.filters['reverse'] = reverse_filter
可以这么用
:::python 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
:::python JINJA2_GLOBALS = {'MEDIA_PREFIX': '/media/'} app.jinja_env.globals.update(JINJA2_GLOBALS)
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)
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)
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
:::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)
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())
上传文件
:::html <form action="/image/upload/" method="post" enctype="multipart/form-data"> <input type="file" name="upload" />
接收
:::python f = request.files.get('upload') img_data = f.read()
直接返回某个文件
:::python 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.
:::python @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
:::python real_ip = request.headers.get('X-Real-Ip', request.remote_addr)
from werkzeug.contrib.fixers import ProxyFix app.wsgi_app = ProxyFix(app.wsgi_app)
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)
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)
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')
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
app.config['HOST']='xxx.a.com' print app.config.get('HOST')
2.环境变量
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
:::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)
