Python的Flask开发框架简单上手笔记
最简单的helloworld
#!/usr/bin/envpython
#encoding:utf-8
fromflaskimportFlask
app=Flask(__name__)
@app.route('/')
defindex():
return'helloworld'
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
fromflaskimportrequest
args=request.argsifrequest.method=='GET'elserequest.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
{%forpageinpages%}
<tr><td><inputtype=checkboxname=do_deletevalue="{{page['id']}}"></td><td>
{%endfor%}
page_ids=request.form.getlist("do_delete")
使用url中的参数
@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
fromflaskimportg app=..... @app.before_request defbefore_request(): g.session=create_session() @app.teardown_request defteardown_request(exception): g.session.close()
注册Jinja2模板中使用的过滤器
@app.template_filter('reverse')
defreverse_filter(s):
returns[::-1]
或者
defreverse_filter(s): returns[::-1] app.jinja_env.filters['reverse']=reverse_filter
可以这么用
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
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
fromflaskimportBlueprint
bp_test=Blueprint('test',__name__)
#bp_test=Blueprint('test',__name__,url_prefix='/abc')
@bp_test.route('/')
--------
fromxxximportbp_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sessionid
app.secret_key='PS#yio`%_!((f_or(%)))s'
然后
fromflaskimportsession
session['somekey']=1
session.pop('logged_in',None)
session.clear()
#过期时间,通过cookie实现的
fromdatetimeimporttimedelta
session.permanent=True
app.permanent_session_lifetime=timedelta(minutes=5)
反向路由
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
<formaction="/image/upload/"method="post"enctype="multipart/form-data"> <inputtype="file"name="upload"/>
接收
f=request.files.get('upload')
img_data=f.read()
直接返回某个文件
returnsend_file(settings.TEMPLATE_FOLDER+'tweet/tweet_list.html')
请求重定向
flask.redirect(location,code=302)theredirectstatuscode.defaultsto302.Supportedcodesare301,302,303,305,and307.300isnotsupported.
@app.route('/')
defhello():
returnredirect(url_for('foo'))
@app.route('/foo')
deffoo():
return'HelloFoo!'
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
fromwerkzeug.contrib.fixersimportProxyFix
app.wsgi_app=ProxyFix(app.wsgi_app)
returnjson&jsonp
importjson
fromflaskimportjsonify,Response,json
data=[]#orothers
returnjsonify(ok=True,data=data)
jsonp_callback=request.args.get('callback','')
ifjsonp_callback:
returnResponse(
"%s(%s);"%(jsonp_callback,json.dumps({'ok':True,'data':data})),
mimetype="text/javascript"
)
returnok_jsonify(data)
配置读取方法
#createourlittleapplication:)
app=Flask(__name__)
#Loaddefaultconfigandoverrideconfigfromanenvironmentvariable
app.config.update(dict(
DATABASE='/tmp/flaskr.db',
DEBUG=True,
SECRET_KEY='developmentkey',
USERNAME='admin',
PASSWORD='default'
))
app.config.from_envvar('FLASKR_SETTINGS',silent=True)
------------------
#configuration
DATABASE='/tmp/minitwit.db'
PER_PAGE=30
DEBUG=True
SECRET_KEY='developmentkey'
#createourlittleapplication:)
app=Flask(__name__)
app.config.from_object(__name__)
app.config.from_envvar('MINITWIT_SETTINGS',silent=True)
几个不常用的方法
fromflaskimportabort,flash
abort
ifnotsession.get('logged_in'):
abort(401)
flash
flash('Newentrywassuccessfullyposted')
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
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`
errorhandler
@app.errorhandler(404)
defnot_found_error(error):
returnrender_template('404.html'),404
@app.errorhandler(500)
definternal_error(error):
db.session.rollback()
returnrender_template('500.html'),500
项目配置
1.直接
app.config['HOST']='xxx.a.com'
printapp.config.get('HOST')
2.环境变量
exportMyAppConfig=/path/to/settings.cfg
app.config.from_envvar('MyAppConfig')
3.对象
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
#default_config.py
HOST='localhost'
PORT=5000
DEBUG=True
app.config.from_pyfile('default_config.py')
EG.一个create_app方法
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=...#dosomething @app.teardown_request defteardown_request(exception): g.xxx=...#dosomething returnapp app=create_app(settings.DEBUG) host=settings.SERVER_IP port=settings.SERVER_PORT app.run(host=host,port=port) changelog: 2013-09-09create 2014-10-25update