A simple decorator for handling tornado http request arguments.

tornado_request.py

def param_schema(**schema):
    """
    请求参数检查装饰器, 使用参数如下:

    key为请求参数，value可以说单个的类型值、(类型值,默认值)元组

    from tornado import web

    class ExampleRequestHandler(web.RequestHandler):

        @param_schema(arg1=(int, 0), arg2=(str, ''), arg3=int)
        def get(self):

            do_request()


    """

    def decorator(func):

        @functools.wraps(func)
        def innerWrapper(request_handler, *args, **kwargs):

            available_arguments = {}

            for arg_key, schema_val in schema.items():
                if not schema_val or (not callable(
                        schema_val) and not isinstance(schema_val, tuple)):
                    continue

                arg_type = None
                arg_hasdefault = False

                if callable(schema_val):
                    # 指定参数类型并且必填
                    arg_type = schema_val
                else:
                    # 指定参数类型或者默认值
                    if len(schema_val) >= 2:
                        arg_type = schema_val[0]
                        default_val = schema_val[1]
                        arg_default = default_val() if callable(
                            default_val) else default_val
                        arg_hasdefault = True
                    elif callable(schema_val[0]):
                        arg_type = schema_val[0]
                    else:
                        arg_default = schema_val[0]
                        arg_hasdefault = True

                if arg_hasdefault:
                    arg_val = request_handler.get_argument(arg_key, arg_default)
                else:
                    arg_val = request_handler.get_argument(arg_key)

                try:
                    available_arguments[arg_key] = arg_type(arg_val) if (
                        arg_type and (
                            not arg_hasdefault or
                            arg_val != arg_default)) else arg_val
                except (ValueError, TypeError):
                    if arg_hasdefault:
                        available_arguments[arg_key] = arg_default
                        continue
                    raise WrongArgumentType(arg_key, arg_val)

            request_handler.ARGS = available_arguments

            return func(request_handler, *args, **kwargs)

        return innerWrapper

    return decorator


def support_methods(request_handler):
    """
    自动获取指定web.RequestHandler支持的HTTP请求方法。
    """

    @functools.wraps(request_handler)
    def innerWrapper(application, request, **kwargs):
        handler_instance = request_handler(application, request, **kwargs)
        all_methods = handler_instance.SUPPORTED_METHODS
        handler_instance.SUPPORTED_METHODS = tuple(set(map(str.upper, (
            name for name in dir(handler_instance)))) & set(all_methods))
        return handler_instance

    return innerWrapper