Python's flask development Framework easy to get started notes

The simplest of Hello World

#!/usr/bin/env python# encoding:utf-8from flask Import Flaskapp = 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)

After that, visit http://localhost:5000

Support Post/get Submission

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

Multiple URLs point to

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

Regardless of whether the Post/get uses a unified receive

From flask Import Requestargs = Request.args if Request.method = = ' GET ' Else Request.forma = args.get (' A ', ' default ')

Working with JSON requests
In the header of request

"Content-type": "Application/json"

When processing:

data = Request.get_json (Silent=false)

Get a checkbox in a post submission

{%for page in pages%}{%endfor%}page_ids = request.form.getlist ("Do_delete")

Using the parameters in the URL

@app. Route ('/query/
 
  
   
  /') def query (qid):  pass
 
  

At the beginning of the request, dosomething
Generally can handle database connection and so on

From flask import GapP = ... @app. Before_requestdef before_request ():  g.session = create_session () @app. Teardown_ Requestdef teardown_request (Exception):  G.session.close ()

Registering the filters used in the JINJA2 template

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

Or

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

You can use this.

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

Registering the global variables used in the JINJA2 template

Jinja2_globals = {' Media_prefix ': '/media/'}app.jinja_env.globals.update (jinja2_globals)

Define the template and static directories used by your app

App = Flask (__name__, template_folder=settings. Template_folder, Static_folder = settings. Static_path)

Using Blueprint

From flask Import blueprintbp_test = Blueprint (' Test ', __name__) #bp_test = Blueprint (' Test ', __name__, url_prefix= '/abc ') ) @bp_test. Route ('/')--------from xxx import Bp_testapp = Flask (__name__) app.register_blueprint (bp_test)

Instance:

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 '/' End, otherwise 404

Use session
Wrapper cookie implementation, no session ID

App.secret_key = ' Ps#yio '%_! ((F_or (%))) s '

And then

From flask import sessionsession[' somekey '] = 1session.pop (' logged_in ', None) session.clear () #过期时间, the from that is implemented via cookies DateTime import timedeltasession.permanent = Trueapp.permanent_session_lifetime = Timedelta (minutes=5)

Reverse route

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 ())

Uploading files

Receive

f = request.files.get (' upload ') Img_data = F.read ()

Return a file directly

return Send_file (settings. Template_folder + ' tweet/tweet_list.html ')

Request redirection

Flask.redirect (location, code=302) the redirect status code. Defaults to 302.Supported codes is 301, 302, 303, 305, and 307. Supported. @app. Route ('/') def hello ():  return Redirect (Url_for (' foo ')) @app. Route ('/foo ') def foo ():  return ' Hello foo! '

Get the user's real IP
Get from Request.headers

REAL_IP = Request.headers.get (' X-real-ip ', request.remote_addr)
Or, use Werkzeug's middleware documentation

From werkzeug.contrib.fixers Import Proxyfixapp.wsgi_app = Proxyfix (App.wsgi_app) return JSON & Jsonpimport Jsonfrom Flask Import Jsonify, Response, Jsondata = [] # or Othersreturn jsonify (ok=true, data=data) Jsonp_callback = REQUEST.ARGS.G ET (' callback ', ') if Jsonp_callback:  return Response (      "%s (%s);"% (Jsonp_callback, json.dumps ({' OK ': True, ' Data ':d ATA}),      mimetype= "Text/javascript"      ) return ok_jsonify (data)

Configuring the Read method

# Create our little application:) app = Flask (__name__) # Load default Config and override config from an environment varia Bleapp.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)------------------# Configurationdatabase = '/tmp/minitwit.db ' per_page = 30DEBUG = Truesecret_key = ' Development KEY ' # Create our little appli cation:) app = Flask (__name__) app.config.from_object (__name__) app.config.from_envvar (' Minitwit_settings ', silent= True)

A few less common methods

From flask Import Abort, flashabortif not Session.get (' logged_in '):  abort (401) flashflash (' New entry ') Successfully posted ')

asynchronous invocation
To handle asynchrony in a request from flask, in addition to using the messaging system, you can use simple threading

From threading Import Threaddef async (f):  def wrapper (*args, **kwargs):    thr = Thread (Target=f, Args=args, Kwargs =kwargs)    Thr.start ()  return wrapper@asyncdef dosomething (Call_args):  print Call_argsin a request handler , call ' dosomething ' error Handler@app.errorhandler (404) def not_found_error (Error):  return render_template (' 404. HTML '), 404@app.errorhandler (+) def internal_error (Error):  db.session.rollback ()  return render_template ( ' 500.html '), 500

Project configuration
1. Direct

app.config[' host ']= ' xxx.a.com ' Print app.config.get (' host ')

2. Environment variables

Export Myappconfig=/path/to/settings.cfgapp.config.from_envvar (' Myappconfig ')

3. Objects

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. Documents

# default_config.pyhost = ' localhost ' PORT = 5000DEBUG = Trueapp.config.from_pyfile (' default_config.py ')

EG. A Create_app method

From flask import flask, gdef 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 Appapp = Create_app (settings. DEBUG) host=settings. Server_ipport=settings. Server_portapp.run (Host=host, Port=port) change log:2013-09-09 create2014-10-25 update

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