typescript：如何声明 function rturn type that inside object

Question

我正在创建一个错误 object，其中包含多个返回 IErrorForm 类型的错误。 but if I focus on a function and set the return type of IErrorFunc, an error occurs in an object such as PermissionDenied and conversely, if I focus on the object and set the return type of IErrorObj, an error occurs in the function.

因此，如果我使用如下联合类型，则错误发生在 function 中。 错误信息是

'类型（来自：字符串）=> {成功：boolean; 代码：号码； 消息：字符串； }'没有属性成功，代码，消息类型'{成功：boolean; 代码：号码； 消息：字符串； }'。 ts(2739)

如何声明 object 的返回类型？

type IErrorForm = {
  sucess: boolean;
  code: number;
  message: string;
};
type IErrorsFunc = {
  (...args: any[]): {
    sucess: boolean;
    code: number;
    message: string;
  };
};

interface IErrorObj {
  [key: string]: { sucess: boolean; code: number; message: string };
}

export const CommonErrors: (IErrorObj | IErrorsFunc) = {
  unexpectedError(from: string) {
    return {
      sucess: false,
      code: 101,
      message: `Unexpected error from ${from}`,
    };
  },
  NotFound(object: string): IErrorForm {
    return {
      sucess: false,
      code: 102,
      message: `${object} not found`,
    };
  },
  permissionDenied: {
    sucess: false,
    code: 103,
    message: 'Permission denied: do not have permission.',
  },
  accessDenied(message: string): IErrorForm {
    return {
      sucess: false,
      code: 104,
      message: `Access denied: ${message}`,
    };
  },
};

Answer 1

看起来您的意图是让CommonErrors成为具有任意键的 object ，其值为IErrorForm或IErrorsFunc 。 如果我们将该类型IErrorObj ，那么它看起来像：

interface IErrorObj {
  [key: string]: IErrorForm | IErrorsFunc;
}

使用string 索引签名为我们提供任意键，以及IErrorForm和IErrorsFunc的联合为我们提供非此即彼的行为。

如果我们这样做，那么您的代码编译不会出错：

export const CommonErrors: IErrorObj = {
  unexpectedError(from: string) {
    return {
      success: false,
      code: 101,
      message: `Unexpected error from ${from}`,
    };
  },
  NotFound(object: string): IErrorForm {
    return {
      success: false,
      code: 102,
      message: `${object} not found`,
    };
  },
  permissionDenied: {
    success: false,
    code: 103,
    message: 'Permission denied: do not have permission.',
  },
  accessDenied(message: string): IErrorForm {
    return {
      success: false,
      code: 104,
      message: `Access denied: ${message}`,
    };
  },
};

还值得注意的是， IErrorForm的返回类型与IErrorsFunc具有相同的形状，这意味着由于结构类型，我们可以重用该类型名称。 因此，您的最终类型集可能如下所示：

interface IErrorForm {
  success: boolean;
  code: number;
  message: string;
}

interface IErrorsFunc {
  (...args: any[]): IErrorForm
}

interface IErrorObj {
  [key: string]: IErrorForm | IErrorsFunc;
}

Playground 代码链接