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   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

Python

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

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

多个url指向

Python

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

1 2	@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')

1 2 3

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"

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

处理时:

Python

data = request.get_json(silent=False)

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")

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{%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

1 2 3

@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()

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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]

1 2 3

@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

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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)

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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)

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

Python

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

1	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)

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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:

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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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)

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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())

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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

 

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

1 2	<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()

1 2	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')

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

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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@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)

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

或者, 使用werkzeug的middleware 文档

Python

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

1 2	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)

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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)

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# 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')

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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

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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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

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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@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

Python

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

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

2.环境变量

Python

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

1 2	export MyAppConfig=/path/to/settings.cfg app.config.from_envvar('MyAppConfig')

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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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

Python

# default_config.py
HOST = 'localhost'
PORT = 5000
DEBUG = True

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

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# 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)

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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)