flask-restful 400 Failed to decode JSON object: Expecting value: line 1 column 1 (char 0)

Steak Overcooked
1

路由地址：api/session post请求

class Session(Resource):
    @marshal_with(t)
    def post(self):
        print('1111111111')
        login_args = login_parser.parse_args()
        user = {}
        user['a'] = login_args.username
        print(user)
        print(login_args.username)
        result = login(login_args.username, login_args.password)
        print(result)
        return result

#login()方法如下
def login(username,password):
    user = User.query.filter_by(username=username).first()
    if user is None:
        return {'msg':'不存在'}
    return {'id':1,
            'success':2,
            'token':3}

#login_parser如下
login_parser = reqparse.RequestParser()

login_parser.add_argument(
    'username', type='str',  location=['json'],required=True, help='用户名参数有误'
)

login_parser.add_argument(
    'password', type='str', location=['json'], required=True, help='密码参数有误'
)

postman请求 在请求头里设置了application/json
请求body

{
    "username":"test",
    "password":"111"
}

现在请求返回400

{
    "message": "Failed to decode JSON object: Expecting value: line 1 column 1 (char 0)"
}
2 
login_parser.add_argument(
    'username', type='str',  location=['json'],required=True, help='用户名参数有误'
)

type 参数应该传一个类型对象，比如 int、str、werkzeug.datastructures.FileStorage，而不是字符串，所以这里要改成 type=str。