Flask 学习-34.Flask-RESTful 请求参数自定义参数校验类型 (reqparse.RequestParser() )

前言

在校验请求参数的时候，除了一些基本的required=True， type类型外，还会遇到一些校验，比如是否为空，字符串长度，以及一些自定义的参数规则。

add_argument 参数

下面是add_argument 可以使用的参数，部分源码如下：

class Argument(object):

    """
    :param name: Either a name or a list of option strings, e.g. foo or
        -f, --foo.
    :param default: The value produced if the argument is absent from the
        request.
    :param dest: The name of the attribute to be added to the object
        returned by :meth:`~reqparse.RequestParser.parse_args()`.
    :param bool required: Whether or not the argument may be omitted (optionals
        only).
    :param action: The basic type of action to be taken when this argument
        is encountered in the request. Valid options are "store" and "append".
    :param ignore: Whether to ignore cases where the argument fails type
        conversion
    :param type: The type to which the request argument should be
        converted. If a type raises an exception, the message in the
        error will be returned in the response. Defaults to :class:`unicode`
        in python2 and :class:`str` in python3.
    :param location: The attributes of the :class:`flask.Request` object
        to source the arguments from (ex: headers, args, etc.), can be an
        iterator. The last item listed takes precedence in the result set.
    :param choices: A container of the allowable values for the argument.
    :param help: A brief description of the argument, returned in the
        response when the argument is invalid. May optionally contain
        an "{error_msg}" interpolation token, which will be replaced with
        the text of the error raised by the type converter.
    :param bool case_sensitive: Whether argument values in the request are
        case sensitive or not (this will convert all values to lowercase)
    :param bool store_missing: Whether the arguments default value should
        be stored if the argument is missing from the request.
    :param bool trim: If enabled, trims whitespace around the argument.
    :param bool nullable: If enabled, allows null value in argument.
    """

    def __init__(self, name, default=None, dest=None, required=False,
                 ignore=False, type=text_type, location=('json', 'values',),
                 choices=(), action='store', help=None, operators=('=',),
                 case_sensitive=True, store_missing=True, trim=False,
                 nullable=True):
        self.name = name
        self.default = default
        self.dest = dest
        self.required = required
        self.ignore = ignore
        self.location = location
        self.type = type
        self.choices = choices
        self.action = action
        self.help = help
        self.case_sensitive = case_sensitive
        self.operators = operators
        self.store_missing = store_missing
        self.trim = trim
        self.nullable = nullable

nullable=False 不允许为None

required=True 设置该参数是必传项， nullable=False 是设置该参数不允许为None

class Register(Resource):

    def post(self):
        # 校验入参
        parser = reqparse.RequestParser()
        parser.add_argument('username', required=True, type=str,  nullable=False, help='username is required')
        parser.add_argument('password', required=True, type=str,  nullable=False, help='password is required')
        args = parser.parse_args()

        # # 获取入参
        # data = request.get_json()
        print(f'请求入参：{args}')
        return jsonify({
            "code": 0,
            "msg": "success"
        })


# 注册
api.add_resource(Register, '/api/v1/register')

需注意的是这里是不能为null, 传空字符串还是可以的。

default=''设置默认值

对address 参数设置默认值，当用户没传address 参数的时候，就会取默认值

    def post(self):
        # 校验入参
        parser = reqparse.RequestParser()
        parser.add_argument('username', required=True, type=str,  nullable=False, help='username is required')
        parser.add_argument('password', required=True, type=str,  nullable=False, help='password is required')
        parser.add_argument('address', default='上海市',  type=str, help='address invalid')
        args = parser.parse_args()
        print(f'请求入参：{args}')

请求示例

POST http://127.0.0.1:5000/api/v1/register HTTP/1.1
User-Agent: Fiddler
Host: 127.0.0.1:5000
Content-Type: application/json
Content-Length: 56

{
    "username": "test",
    "password" : "111111"
}

args 得到的参数

{'username': 'test', 'password': '111111', 'address': '上海市'}

choices 设置参数可选值

比如性别设置可选项：男、女

    def post(self):
        # 校验入参
        parser = reqparse.RequestParser()
        parser.add_argument('username', required=True, type=str,  nullable=False, help='username is required')
        parser.add_argument('password', required=True, type=str,  nullable=False, help='password is required')
        parser.add_argument('sex', choices=["男", "女"],  type=str, help='sex invalid')
        args = parser.parse_args()

        print(f'请求入参：{args}')

请求示例，sex不是可选项的时候会报400

POST http://127.0.0.1:5000/api/v1/register HTTP/1.1
User-Agent: Fiddler
Host: 127.0.0.1:5000
Content-Type: application/json
Content-Length: 73

{
    "username": "test",
    "password" : "111111",
    "sex": "x"
}

HTTP/1.1 400 BAD REQUEST
Server: Werkzeug/2.2.2 Python/3.8.5
Date: Thu, 01 Sep 2022 13:40:14 GMT
Content-Type: application/json
Content-Length: 57
Connection: close

{
    "message": {
        "sex": "sex invalid"
    }
}

设置字符串长度

比如限制 password 是 6-16 位，由于 add_argument 没提供对应的方法，需我们自定义参数校验类型

class Register(Resource):

    @staticmethod
    def password_validate(value, name):
        if len(value) < 6 or len(value) > 16:
            raise ValueError(name + '参数长度不合法')
        return value

    def post(self):
        # 校验入参
        parser = reqparse.RequestParser()
        parser.add_argument('username', required=True, type=str,  nullable=False, help='username invalid')
        parser.add_argument('password', required=True, type=self.password_validate,  
                            nullable=False, help='password invalid must 6-16')
        # parser.add_argument('sex', choices=["男", "女"],  type=str, help='sex invalid')
        args = parser.parse_args()

        print(f'请求入参：{args}')

如果密码长度小于6位，会返回400

POST http://127.0.0.1:5000/api/v1/register HTTP/1.1
User-Agent: Fiddler
Host: 127.0.0.1:5000
Content-Type: application/json
Content-Length: 55

{
    "username": "test",
    "password" : "12345"
}

HTTP/1.1 400 BAD REQUEST
Server: Werkzeug/2.2.2 Python/3.8.5
Date: Thu, 01 Sep 2022 14:04:30 GMT
Content-Type: application/json
Content-Length: 76
Connection: close

{
    "message": {
        "password": "password invalid must 6-16"
    }
}