Question

我为试图构建客户端的响应定义了接口，我看到data的响应来自后端，因此现在我正尝试为接口对象分配值，而该对象未定义。不确定为什么会引起这个问题吗？

main.ts

  private async specialtyAccountBalanceResponse(@Body()data: IAccountBalanceSdkResult): Promise<any> {
      const saveDetails = {} as ICacheRequest;
      const specialtyResponse = {} as IGetAccountBalanceResponse;

      if (!data.Details && data.Header.StatusCode !== "0000") {
          return data.Header;
      }
      specialtyResponse.details.lineOfBusiness = "SPec";
      specialtyResponse.details.balanceAccount = data.Details.balanceAccount;
      return specialtyResponse;
  }

interface.ts

export interface IGetAccountBalanceResponse {
    header: any;
    details: IGetAccountBalanceDetails;
}

export interface IGetAccountBalanceDetails {
    lineOfBusiness: string;
    balanceAccount: string;
    payment: IPaymentIndicator;
}

export interface IPaymentIndicator {
    recentPaymentIndicator: string;
    recentPaymentAmount: string;
    achAuthRequiredInd: string;
}

Answer 1

您宁愿定义一个类而不是一个接口：

export class IGetAccountBalanceResponse {

    constructor(props?) {
       this.header = props.header;
       this.details = props.details;
    }

    public header: any;
    public details: IGetAccountBalanceDetails; 
}

然后您可以像这样实例化它：

const balance = new IGetAccountBalanceResponse()

或

const balance = new IGetAccountBalanceResponse(data)

这也可行，但除非有充分的理由，否则不应该这样做

const balance: IGetAccountBalanceResponse = {} as any;

接口不应用于实例化对象，而应用于定义其类型。

如果使用诸如eslint之类的linter（我强烈建议这样做），则在编译之前会弹出该错误。

在这里您可以尝试： http://www.typescriptlang.org/play/

Here are the official docs on it

Here is a working example

Answer 2

在您的示例中，您创建一个空对象：

const specialtyResponse = {} as IGetAccountBalanceResponse;

然后，您尝试访问它的属性：

specialtyResponse.details.lineOfBusiness = "SPec";

details从未实例化，因此为undefined。因此，您无法访问其属性lineOfBusiness。

一种解决方案是使用@undefinedMayNotBeNull建议的类。另一个方法是在访问属性之前先设置specialtyResponse.details。

specialtyResponse.details = {} as IGetAccountBalanceDetails;

这是一个可行的示例：

interface IGetAccountBalanceResponse {
    details: IGetAccountBalanceDetails;
}

interface IGetAccountBalanceDetails {
    lineOfBusiness: string;
    balanceAccount: string;
}

const specialtyResponse = {} as IGetAccountBalanceResponse;
specialtyResponse.details = {} as IGetAccountBalanceDetails;

specialtyResponse.details.lineOfBusiness = "SPec";
specialtyResponse.details.balanceAccount = "Test";

Try it on TypeScript Playground

更新

specialtyResponse可能是错字。您是说specialityResponse吗？

如何为已定义的接口分配值？

2 个答案: