flask-restful使用指南

flask-restful是flask模块的一个扩展，能够快速构建restful风格的api。对于其他的扩展也有很高的兼容性。
安装flask_restful
pip install flask_restful
简单使用

from flask import Flask

from flask_restful import Resource, Api

app = Flask(__name__)

api = Api(app)

class TestRestful(Resource):

    def get(self):

        return {'hello': 'restful'}

api.add_resource(TestRestful, '/')

if __name__ == '__main__':

    app.run()

演示结果

C:\Users\jh>curl http://127.0.0.1:5000/
{"hello": "restful"}

Flask-RESTful 提供的主要构建块是资源。资源构建在 Flask 可插入视图之上，
只需在资源上定义方法，就可以轻松访问多个 HTTP 方法。一个 todo 应用程序的基本 CRUD 资源是这样的:

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]}

api.add_resource(TodoSimple, '/<string:todo_id>')

if __name__ == '__main__':

    app.run()

　演示结果

执行
curl http://127.0.0.1:5000/todo1 -d "data=hello restful" -X put
返回 {"todo1": "hello restful"}
执行 curl http://127.0.0.1:5000/todo1
返回 {"todo1": "hello restful"}
curl http://127.0.0.1:5000/todo2 -d "data=good restful" -X put
返回 {"todo2": "good restful"}
执行 curl http://127.0.0.1:5000/todo2
返回 {"todo2": "good restful"}

Restful 能够从 view 方法中理解多种返回值。类似于 Flask，你可以返回任何可迭代的并且它将被转换成一个响应，
包括原始 Flask 响应对象。还支持使用多个返回值设置响应代码和响应头，如下所示:

from flask import Flask

from flask_restful import Resource, Api

app = Flask(__name__)

api = Api(app)

class Todo1(Resource):

    def get(self):

        return {'msg': 'hello restful'}

class Todo2(Resource):

    def get(self):

        return {'msg': 'hello restful'}, 201

class Todo3(Resource):

    def get(self):

        return {'msg': 'hello restful'}, 201, {'new_tag': 'this is new_tag'}

api.add_resource(Todo1, '/todo1')

api.add_resource(Todo2, '/todo2')

api.add_resource(Todo3, '/todo3')

if __name__ == '__main__':

    app.run()

　　演示结果

C:\Users\jh>curl -i http://127.0.0.1:5000/todo1
HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 25
Server: Werkzeug/2.0.1 Python/3.8.6
Date: Tue, 16 Aug 2022 10:25:25 GMT

{"msg": "hello restful"} # return 的msg

很多时候，在一个 API 中，你的资源会有多个 url。可以将多个 url 传递给 Api 对象上的 add _ resource ()方法。
每一个都将被路由到Resource

from flask import Flask

from flask_restful import Resource, Api

app = Flask(__name__)

api = Api(app)

class TestRestful(Resource):

    def get(self):

        return {'hello': 'restful'}

class Todo(Resource):

    def get(self, todo_id):

        return {'msg': 'hello todo'}

api.add_resource(TestRestful, '/', '/test')

api.add_resource(Todo, '/todo/<int:todo_id>', endpoint='todo_ep')

if __name__ == '__main__':

    app.run()

　　演示结果

C:\Users\jh>curl -i http://127.0.0.1:5000/todo2
HTTP/1.0 201 CREATED # return的状态码
Content-Type: application/json
Content-Length: 25
Server: Werkzeug/2.0.1 Python/3.8.6
Date: Tue, 16 Aug 2022 10:25:27 GMT

{"msg": "hello restful"} # return 的msg

C:\Users\jh>curl -i http://127.0.0.1:5000/todo3
HTTP/1.0 201 CREATED # return的状态码
Content-Type: application/json
Content-Length: 25
new_tag: this is new_tag #return 的new_tag
Server: Werkzeug/2.0.1 Python/3.8.6
Date: Tue, 16 Aug 2022 10:25:32 GMT

{"msg": "hello restful"} # return 的msg

C:\Users\jh>curl -i http://127.0.0.1:5000/
HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 21
Server: Werkzeug/2.0.1 Python/3.8.6
Date: Tue, 16 Aug 2022 10:58:32 GMT

{"hello": "restful"}

C:\Users\jh>curl -i http://127.0.0.1:5000/test
HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 21
Server: Werkzeug/2.0.1 Python/3.8.6
Date: Tue, 16 Aug 2022 10:58:42 GMT

{"hello": "restful"}

C:\Users\jh>curl -i http://127.0.0.1:5000/todo/1
HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 22
Server: Werkzeug/2.0.1 Python/3.8.6
Date: Tue, 16 Aug 2022 10:59:02 GMT

{"msg": "hello todo"}

C:\Users\jh>curl -i http://127.0.0.1:5000/todo/2
HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 22
Server: Werkzeug/2.0.1 Python/3.8.6
Date: Tue, 16 Aug 2022 10:59:06 GMT

{"msg": "hello todo"}

虽然 Flask 可以方便地访问请求数据(即 querystring 或 POST 表单编码的数据) ，
但验证表单数据仍然是一件痛苦的事情。使用类似于 argparse 的库对请求数据验证提供内置支持。

from flask import Flask

from flask_restful import reqparse, Resource, Api

app = Flask(__name__)

api = Api(app)

parser = reqparse.RequestParser()

parser.add_argument('rate', type=int, help='rate to change for this resource')

class Todo(Resource):

    def post(self):

        args = parser.parse_args()

        print('args: %s' % args)

        return {'msg': 'hello333 restful'}

    def get(self):

        args = parser.parse_args()

        print('args: %s' % args)

        return {'msg': 'hello444 restful'}

api.add_resource(Todo, '/todos')

if __name__ == '__main__':

    app.run(debug=True)

　　演示结果

使用curl时，-d 后面的参数需要用双引号，否则可能获取不到参数
C:\Users\jh>curl -H "charset=utf-8" -d 'rate=110' http://127.0.0.1:5000/todos
{
"msg": "hello333 restful"
}

C:\Users\jh>curl -d "rate=123" http://127.0.0.1:5000/todos
{
"msg": "hello333 restful"
}

C:\Users\jh>curl -d "rate=123s" http://127.0.0.1:5000/todos
{
"message": {
"rate": "rate to change for this resource"
}
}

C:\Users\jh>curl http://127.0.0.1:5000/todos?rate=234
{
"msg": "hello444 restful"
}

C:\Users\jh>curl http://127.0.0.1:5000/todos?rate2=234
{
"msg": "hello444 restful"
}
服务端日志
127.0.0.1 - - [18/Aug/2022 11:04:44] "POST /todos HTTP/1.1" 200 -
args: {'rate': None}
127.0.0.1 - - [18/Aug/2022 11:04:51] "POST /todos HTTP/1.1" 200 -
args: {'rate': None}
127.0.0.1 - - [18/Aug/2022 11:04:54] "POST /todos HTTP/1.1" 200 -
args: {'rate': 123}
127.0.0.1 - - [18/Aug/2022 11:05:30] "POST /todos HTTP/1.1" 400 -
args: {'rate': 234}
127.0.0.1 - - [18/Aug/2022 11:06:08] "GET /todos?rate=234 HTTP/1.1" 200 -
127.0.0.1 - - [18/Aug/2022 11:06:12] "GET /todos?rate2=234 HTTP/1.1" 200 -
args: {'rate': None}

默认情况下，在你的返回迭代中所有字段将会原样呈现。尽管当你刚刚处理 Python 数据结构的时候，觉得这是一个伟大的工作，
但是当实际处理它们的时候，会觉得十分沮丧和枯燥。为了解决这个问题，Flask-RESTful 提供了 fields 模块和 marshal_with() 装饰器。
类似 Django ORM 和 WTForm，你可以使用 fields 模块来在你的响应中格式化结构。

from flask import Flask

from flask_restful import Resource, Api, fields, marshal_with

app = Flask(__name__)

api = Api(app)

resource_fields = {

    'task': fields.String,

    'uri': fields.Url('todo')

}

class TodoDao(object):

    def __init__(self, todo_id, task):

        self.todo_id = todo_id

        self.task = task

        self.status = 'active'

class Todo(Resource):

    @marshal_with(resource_fields)

    def get(self, **kwargs):

        return TodoDao(todo_id='my_todo', task='watch the car')

api.add_resource(Todo, '/todo')

if __name__ == '__main__':

    app.run(debug=True)

C:\Users\jh>curl http://127.0.0.1:5000/todo
{
"task": "watch the car",
"uri": "/todo"
}

from flask import Flask

from flask_restful import Resource, Api, reqparse, abort

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')

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

class TodoList(Resource):

    def get(self, **kwargs):

        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

api.add_resource(TodoList, '/todos')

api.add_resource(Todo, '/todos/<todo_id>')

if __name__ == '__main__':

    app.run(debug=True)

　　演示结果

C:\Users\jh>curl http://127.0.0.1:5000/todos
{
"todo1": {
"task": "build an api"
},
"todo2": {
"task": "??????"
},
"todo3": {
"task": "profit!"
}
}

C:\Users\jh>curl http://127.0.0.1:5000/todos/todo3
{
"task": "profit!"
}

C:\Users\jh>curl http://127.0.0.1:5000/todos/todo4
{
"message": "Todo todo4 doesn't exist"
}

C:\Users\jh>curl http://localhost:5000/todos/todo2 -X DELETE -v
* Trying 127.0.0.1:5000...
* Connected to localhost (127.0.0.1) port 5000 (#0)
> DELETE /todos/todo2 HTTP/1.1
> Host: localhost:5000
> User-Agent: curl/7.83.1
> Accept: */*
>
* Mark bundle as not supporting multiuse
* HTTP 1.0, assume close after body
< HTTP/1.0 204 NO CONTENT
< Content-Type: application/json
< Server: Werkzeug/2.0.1 Python/3.8.6
< Date: Thu, 18 Aug 2022 06:10:09 GMT
<
* Closing connection 0

C:\Users\jh>curl http://127.0.0.1:5000/todos/todo2
{
"message": "Todo todo2 doesn't exist"
}

C:\Users\jh>curl http://localhost:5000/todos -d "task=something new" -X POST -v
Note: Unnecessary use of -X or --request, POST is already inferred.
* Trying 127.0.0.1:5000...
* Connected to localhost (127.0.0.1) port 5000 (#0)
> POST /todos HTTP/1.1
> Host: localhost:5000
> User-Agent: curl/7.83.1
> Accept: */*
> Content-Length: 18
> Content-Type: application/x-www-form-urlencoded
>
* Mark bundle as not supporting multiuse
* HTTP 1.0, assume close after body
< HTTP/1.0 201 CREATED
< Content-Type: application/json
< Content-Length: 32
< Server: Werkzeug/2.0.1 Python/3.8.6
< Date: Thu, 18 Aug 2022 06:10:53 GMT
<
{
"task": "something new"
}
* Closing connection 0

C:\Users\jh>curl http://127.0.0.1:5000/todos/todo4
{
"task": "something new"
}

C:\Users\jh>curl http://localhost:5000/todos/todo3 -d "task=something different" -X PUT -v
* Trying 127.0.0.1:5000...
* Connected to localhost (127.0.0.1) port 5000 (#0)
> PUT /todos/todo3 HTTP/1.1
> Host: localhost:5000
> User-Agent: curl/7.83.1
> Accept: */*
> Content-Length: 24
> Content-Type: application/x-www-form-urlencoded
>
* Mark bundle as not supporting multiuse
* HTTP 1.0, assume close after body
< HTTP/1.0 201 CREATED
< Content-Type: application/json
< Content-Length: 38
< Server: Werkzeug/2.0.1 Python/3.8.6
< Date: Thu, 18 Aug 2022 06:15:31 GMT
<
{
"task": "something different"
}
* Closing connection 0

C:\Users\jh>curl http://127.0.0.1:5000/todos/todo3
{
"task": "something different"
}

C:\Users\jh>curl http://127.0.0.1:5000/todos
{
"todo1": {
"task": "build an api"
},
"todo3": {
"task": "something different"
},
"todo4": {
"task": "something new"
}
}

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