使用Python & Flask 实现RESTful Web API的实例


            环境安装：

sudo pip install flask

Flask 是一个Python的微服务的框架，基于Werkzeug, 一个 WSGI 类库。

Flask 优点:

Written in Python (that can be an advantage);

Simple to use;

Flexible;

Multiple good deployment options;

RESTful request dispatching



RESOURCES

一个响应 /articles 和 /articles/:id的 API 服务：





from flask import Flask, url_for

app = Flask(__name__)



@app.route('/')

def api_root():

 return 'Welcome'



@app.route('/articles')

def api_articles():

 return 'List of ' + url_for('api_articles')



@app.route('/articles/<articleid>')

def api_article(articleid):

 return 'You are reading ' + articleid



if __name__ == '__main__':

 app.run()



请求：

curl http://127.0.0.1:5000/

响应：

GET /

Welcome

GET /articles

List of /articles

GET /articles/123

You are reading 123



REQUESTS

GET Parameters





from flask import request



@app.route('/hello')

def api_hello():

 if 'name' in request.args:

  return 'Hello ' + request.args['name']

 else:

  return 'Hello John Doe'



请求：

GET /hello

Hello John Doe

GET /hello?name=Luis

Hello Luis

Request Methods (HTTP Verbs)





@app.route('/echo', methods = ['GET', 'POST', 'PATCH', 'PUT', 'DELETE'])

def api_echo():

 if request.method == 'GET':

  return "ECHO: GET\n"



 elif request.method == 'POST':

  return "ECHO: POST\n"



 elif request.method == 'PATCH':

  return "ECHO: PACTH\n"



 elif request.method == 'PUT':

  return "ECHO: PUT\n"



 elif request.method == 'DELETE':

  return "ECHO: DELETE"



请求指定request type：

curl -X PATCH http://127.0.0.1:5000/echo

GET /echo

ECHO: GET

POST /ECHO

ECHO: POST

Request Data & Headers





from flask import json



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

def api_message():



 if request.headers['Content-Type'] == 'text/plain':

  return "Text Message: " + request.data



 elif request.headers['Content-Type'] == 'application/json':

  return "JSON Message: " + json.dumps(request.json)



 elif request.headers['Content-Type'] == 'application/octet-stream':

  f = open('./binary', 'wb')

  f.write(request.data)

    f.close()

  return "Binary message written!"



 else:

  return "415 Unsupported Media Type ;)"



请求指定content type：

curl -H "Content-type: application/json" \

-X POST http://127.0.0.1:5000/messages -d '{"message":"Hello Data"}'

curl -H "Content-type: application/octet-stream" \

-X POST http://127.0.0.1:5000/messages --data-binary @message.bin

RESPONSES





from flask import Response



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

def api_hello():

 data = {

  'hello' : 'world',

  'number' : 3

 }

 js = json.dumps(data)



 resp = Response(js, status=200, mimetype='application/json')

 resp.headers['Link'] = 'http://luisrei.com'



 return resp



查看response HTTP headers：

curl -i http://127.0.0.1:5000/hello

优化代码：

from flask import jsonify

使用





resp = jsonify(data)

resp.status_code = 200



替换





resp = Response(js, status=200, mimetype='application/json')



Status Codes & Errors





@app.errorhandler(404)

def not_found(error=None):

 message = {

   'status': 404,

   'message': 'Not Found: ' + request.url,

 }

 resp = jsonify(message)

 resp.status_code = 404



 return resp



@app.route('/users/<userid>', methods = ['GET'])

def api_users(userid):

 users = {'1':'john', '2':'steve', '3':'bill'}

 

 if userid in users:

  return jsonify({userid:users[userid]})

 else:

  return not_found()



请求：

GET /users/2

HTTP/1.0 200 OK

{

"2": "steve"

}

GET /users/4

HTTP/1.0 404 NOT FOUND

{

"status": 404, 

"message": "Not Found: http://127.0.0.1:5000/users/4"

}

AUTHORIZATION





from functools import wraps



def check_auth(username, password):

 return username == 'admin' and password == 'secret'



def authenticate():

 message = {'message': "Authenticate."}

 resp = jsonify(message)



 resp.status_code = 401

 resp.headers['WWW-Authenticate'] = 'Basic realm="Example"'



 return resp



def requires_auth(f):

 @wraps(f)

 def decorated(*args, **kwargs):

  auth = request.authorization

  if not auth: 

   return authenticate()



  elif not check_auth(auth.username, auth.password):

   return authenticate()

  return f(*args, **kwargs)



 return decorated



replacing the check_auth function and using the requires_auth decorator:

@app.route('/secrets')

@requires_auth

def api_hello():

return "Shhh this is top secret spy stuff!"

HTTP basic authentication：

curl -v -u "admin:secret" http://127.0.0.1:5000/secrets

SIMPLE DEBUG & LOGGING

Debug:

app.run(debug=True)

Logging：





import logging

file_handler = logging.FileHandler('app.log')

app.logger.addHandler(file_handler)

app.logger.setLevel(logging.INFO)



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

def api_hello():

 app.logger.info('informing')

 app.logger.warning('warning')

 app.logger.error('screaming bloody murder!')

 

 return "check your logs\n"



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