Typescript 装饰器 - 接受的参数太少，无法在此处用作装饰器

Question

我正在尝试编写一个装饰器，它接受一个方法并在该方法未在指定超时(使用方法参数指定)内完成时抛出错误。不指定超时应该导致方法运行，就好像参数不存在一样。

export const setMethodTimeout = (): Function => {
  return function(target: any, propertyKey: string | symbol, descriptor: PropertyDescriptor) {
    const context = this;
    const args: DecoratorArgumentType = arguments;
    if (args.timeout) {
      const timer = setTimeout(() => {
        throw new Error('The method did not finish before the specified timeout.');
      }, args.timeout);
      const originalMethod = descriptor.value;
      descriptor.value = function() {
        originalMethod
          .apply(context, args)
          .then((result: any) => {
            clearTimeout(timer);
            return result;
          })
          .catch((e: Error) => {
            throw e;
          });
      };
    }
    return descriptor;
  };
};

现在当我尝试在我的类方法上使用这个装饰器时:

@setMethodTimeout
public async getMap(params: GetMapParams, api: ApiType, reqConfig?: RequestConfiguration): Promise<Blob> {
   //...
}

我收到以下 typescript 错误:

‘setMethodTimeout’ accepts too few arguments to be used as a decorator here. Did you mean to call it first and write ‘@setMethodTimeout()’?

为什么会这样？

Answer 1

它需要一个函数调用，因为您要用附加函数 setMethodTimeout 包装装饰器。如果您像这样删除它，它将在没有函数调用语法的情况下工作:

export const function setMethodTimeout(target: any, propertyKey: string | symbol, descriptor: PropertyDescriptor) {
    const context = this;
    const args: DecoratorArgumentType = arguments;
    if (args.timeout) {
      const timer = setTimeout(() => {
        throw new Error('The method did not finish before the specified timeout.');
      }, args.timeout);
      const originalMethod = descriptor.value;
      descriptor.value = function() {
        originalMethod
          .apply(context, args)
          .then((result: any) => {
            clearTimeout(timer);
            return result;
          })
          .catch((e: Error) => {
            throw e;
          });
      };
    }
    return descriptor;
};