Flask-RESTful 快速入门
hello world
from flask import Flask
from flask_restful import Resource, Api
app = Flask(__name__)
api = Api(app)
class HelloWorld(Resource):
def get(self):
return {'hello': 'world'}
api.add_resource(HelloWorld, '/')
if __name__ == '__main__':
app.run(debug=True)
资源
资源 (Resource) 是 Flask-RESTful 中最主要的概念. 资源就是 Flask pluggable views 的子类, 因此可以很容易的定义 HTTP 方法. 一个简单的 CRUD 程序看起来如下:
from flask import Flask, request
from flask_restful import Resource, Api
app = Flask(__name__)
api = Api(app)
todos = {}
class TodoSimple(Resource):
def get(self, todo_id):
return {todo_id: todos[todo_id]}
def put(self, todo_id):
todos[todo_id] = request.form['data']
return {todo_id: todos[todo_id]}
// 将 TodoSimple 挂载在 '/<string:todo_id>' 路由上
api.add_resource(TodoSimple, '/<string:todo_id>')
if __name__ == '__main__':
app.run(debug=True)
Flask-RESTful 能够处理各种类型返回值, 将其转换成合适的响应.
class Todo1(Resource):
def get(self):
# 默认 HTTP Status Code 为 200
return {'task': 'Hello world'}
class Todo2(Resource):
def get(self):
# 设置 HTTP Status Code 为 201
return {'task': 'Hello world'}, 201
class Todo3(Resource):
def get(self):
# 设置 HTTP Status Code 为 201 并返回自定义 headers
return {'task': 'Hello world'}, 201, {'Etag': 'some-opaque-string'}
Endpoints
一个资源可以挂载在多个路由上:
api.add_resource(HelloWorld,
'/',
'/hello')
可以将路由作为参数
api.add_resource(Todo,
'/todo/<int:todo_id>', endpoint='todo_ep')
参数解析
虽然 Flask 提供了简单的方法访问请求数据, 但是对于表单数据处理还是很痛苦. Flask-RESTful 提供了 reqparse 一种类似 argparse 参数解析机制以简化参数处理.
from flask_restful import reqparse
parser = reqparse.RequestParser()
parser.add_argument('rate', type=int, help='Rate to charge for this resource')
// strict 如果提供未定义的参数, 那么就抛出异常
args = parser.parse_args(strict=True)
数据格式化
Flask 能很好的处理 Python 内置的数据结构, Flask-RESTful 提供了处理自定义对象的 fields 模块和 marshal_with() 方法
from collections import OrderedDict
from flask_restful import fields, marshal_with
resource_fields = {
'task': fields.String,
'uri': fields.Url('todo_ep')
}
class TodoDao(object):
def __init__(self, todo_id, task):
self.todo_id = todo_id
self.task = task
# This field will not be sent in the response
self.status = 'active'
class Todo(Resource):
@marshal_with(resource_fields)
def get(self, **kwargs):
return TodoDao(todo_id='my_todo', task='Remember the milk')
上例中 get 返回一个 TodoDao 对象, 使用 marshal_with 装饰器根据 resource_fields 序列化这个对象. 这里只有一个字段被序列化, 就是 task.
总结
Flask-RESTful 的使用基本上就是用 reqparse 处理请求, 使用 fields 来处理返回值, 输出响应.
完整的例子
from flask import Flask
from flask_restful import reqparse, abort, Api, Resource
app = Flask(__name__)
api = Api(app)
TODOS = {
'todo1': {'task': 'build an API'},
'todo2': {'task': '?????'},
'todo3': {'task': 'profit!'},
}
def abort_if_todo_doesnt_exist(todo_id):
if todo_id not in TODOS:
abort(404, message="Todo {} doesn't exist".format(todo_id))
parser = reqparse.RequestParser()
parser.add_argument('task')
# Todo
# shows a single todo item and lets you delete a todo item
class Todo(Resource):
def get(self, todo_id):
abort_if_todo_doesnt_exist(todo_id)
return TODOS[todo_id]
def delete(self, todo_id):
abort_if_todo_doesnt_exist(todo_id)
del TODOS[todo_id]
return '', 204
def put(self, todo_id):
args = parser.parse_args()
task = {'task': args['task']}
TODOS[todo_id] = task
return task, 201
# TodoList
# shows a list of all todos, and lets you POST to add new tasks
class TodoList(Resource):
def get(self):
return TODOS
def post(self):
args = parser.parse_args()
todo_id = int(max(TODOS.keys()).lstrip('todo')) + 1
todo_id = 'todo%i' % todo_id
TODOS[todo_id] = {'task': args['task']}
return TODOS[todo_id], 201
##
## Actually setup the Api resource routing here
##
api.add_resource(TodoList, '/todos')
api.add_resource(Todo, '/todos/<todo_id>')
if __name__ == '__main__':
app.run(debug=True)