使用Python & Flask 实现RESTful Web API的实例

2020-01-04 16:46:04

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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(): 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 ' + articleidif __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 wrapsdef 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 respdef 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 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.warning('warning') app.logger.error('screaming bloody murder!')  return "check your logs/n"

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