使用 Python & Flask 实现 RESTful Web API

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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_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/')
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

from flask import json

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/', 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"

参考:

Flask documentation(http://flask.pocoo.org/docs/0.12/)

Flask snippets(http://flask.pocoo.org/snippets/)

Werkzeug documentation(http://werkzeug.pocoo.org/docs/0.12/)

curl manual(https://curl.haxx.se/docs/manual.html)

作者:阿凡卢
出处:http://www.cnblogs.com/luxiaoxun/
本文版权归作者和博客园共有,欢迎转载,但未经作者同意必须保留此段声明,且在文章页面明显位置给出原文连接,否则保留追究法律责任的权利。

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