使用 Python & Flask 实现 RESTful Web API

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_forapp = Flask(__name__)@app.route('/')def api_root():retu 'Welcome'@app.route('/articles')def api_articles():retu 'List of ' + url_for('api_articles')@app.route('/articles/<articleid>')def api_article(articleid):retu 'You are reading ' + articleidif __name__ == '__main__':app.run()

请求：

curl http://127.0.0.1:5000/

响应：

GET /WelcomeGET /articlesList of /articlesGET /articles/123You are reading 123

REQUESTS

GET Parameters

from flask import request@app.route('/hello')def api_hello():if 'name' in request.args:retu 'Hello ' + request.args['name']else:retu 'Hello John Doe'

请求：

GET /helloHello John DoeGET /hello?name=LuisHello Luis

Request Methods (HTTP Verbs)

@app.route('/echo', methods = ['GET', 'POST', 'PATCH', 'PUT', 'DELETE'])def api_echo():if request.method == 'GET':retu "ECHO: GET\n"elif request.method == 'POST':retu "ECHO: POST\n"elif request.method == 'PATCH':retu "ECHO: PACTH\n"elif request.method == 'PUT':retu "ECHO: PUT\n"elif request.method == 'DELETE':retu "ECHO: DELETE"

请求指定request type：

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

GET /echoECHO: GETPOST /ECHOECHO: POST

Request Data & Headers

from flask import json@app.route('/messages', methods = ['POST'])def api_message():if request.headers['Content-Type'] == 'text/plain':retu "Text Message: " + request.dataelif request.headers['Content-Type'] == 'application/json':retu "JSON Message: " + json.dumps(request.json)elif request.headers['Content-Type'] == 'application/octet-stream':f = open('./binary', 'wb')f.write(request.data)f.close()retu "Binary message written!"else:retu "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'retu 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 = 404retu resp@app.route('/users/<userid>', methods = ['GET'])def api_users(userid):users = {'1':'john', '2':'steve', '3':'bill'}if userid in users:retu jsonify({userid:users[userid]})else:retu not_found()

请求：

GET /users/2HTTP/1.0 200 OK{"2": "steve"}GET /users/4HTTP/1.0 404 NOT FOUND{"status": 404, "message": "Not Found: http://127.0.0.1:5000/users/4"}

AUTHORIZATION

from functools import wrapsdef check_auth(useame, password):retu useame == 'admin' and password == 'secret'def authenticate():message = {'message': "Authenticate."}resp = jsonify(message)resp.status_code = 401resp.headers['WWW-Authenticate'] = 'Basic realm="Example"'retu respdef requires_auth(f):@wraps(f)def decorated(*args, **kwargs):auth = request.authorizationif not auth: retu authenticate()elif not check_auth(auth.useame, auth.password):retu authenticate()retu f(*args, **kwargs)retu decorated

replacing the check_auth function and using the requires_auth decorator:

@app.route('/secrets')@requires_authdef api_hello():retu "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 loggingfile_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.waing('waing')app.logger.error('screaming bloody murder!')retu "check your logs\n"

 

参考：

Flask documentation

Flask snippets

Werkzeug documentation

curl manual