HTTP请求参数解析器实现

HTTP请求参数

• GET / DELETE 查询参数/URL参数
  • https://www.baidu.com/?key=123
  • request.GET = {“key”: “123”}
• POST / PATCH / PUT
  • 请求体（body）application/json www-xxxx form-data
  • request.POST {“key”: “123”}

解析器实现目标

• 能解析GET/POST参数
• 参数校验
  • 参数类型，例如必需是int
  • 必填判断
  • 自定义校验，例如该参数只是能(“a”, “b”, “c”)中的一个

代码实现

import json

body = {
    "id": "12",
    "url": "https://gitee.com/yooke/User.git",
    "type": "c",
}

# request.GET
# request.POST
# application/json   json.loads(request.body)


body = json.dumps(body)


class Argument:
    def __init__(self, key, required=True, filter=None, type=None, help=None):
        self.key = key
        self.required = required
        self.filter = filter
        self.type = type
        self.help = help


class Parser:
    def __init__(self, *arguments):
        self.arguments = arguments

    def parse(self, data):
        form, error = {}, None
        for arg in self.arguments:
            value = data.get(arg.key)
            if arg.required and value is None:  # 判断required属性是否必填
                error = arg.help
                break
            if arg.type:  # 判断type属性类型是否正确
                if not isinstance(value, arg.type):
                    try:
                        value = arg.type(value)  # 尝试转换类型
                    except ValueError:
                        error = arg.help
                        break
            if arg.filter and not arg.filter(value):  # 判断是否符合filter过滤条件
                error = arg.help
                break
            form[arg.key] = value
        return form, error


class JSONParser(Parser):  # 扩展解析JSON消息体
    def parse(self, data):
        data = json.loads(data)
        return super().parse(data)


class XMLParser(Parser):   # 扩展解析XML消息体
    def xmltodict(self, data):
        # TODO: xml to dict
        return data

    def parse(self, data):
        data = self.xmltodict(data)
        return super().parse(data)


def main():
    form, error = JSONParser(
        Argument('id', type=int, help='ID必须是整数'),
        Argument('name', required=False, help='name参数必填'),
        Argument('url', help='url参数必填'),
        Argument('type', filter=lambda x: x in ('a', 'b', 'c'), help='type参数必须是a,b,c中的一个'),
    ).parse(body)
    if error is None:
        print('参数校验通过: ', form)
    else:
        print('参数校验失败: ', error)


main()