Map from one interface to another-CodePudding

I'm coming from Java and I usually use DTO to map to Entity and vice-versa. But I'm having a hard time to do this in Typescript Nodejs. What I have are two interfaces:

export interface IOne {
    clientId: number;
    clientName: string;
    ...
}

export interface ITwo {
    userId: number;
    userName: string;
    ...
}

A GET call is received on Interface One format and Interface Two is responsible to grab this response and make a POST request after.

The bellow implementation gets undefined:

let userTwo: ITwo;

userTwo.map(data => {
    return <ITwo> {
        userId: data.clientId,
        userName: data.clientName,
        ...
    };
});

What is the right way in Typescript/Nodejs to Map the returned response in one interface format then convert to another Interface format in DTO to Domain Object pattern?

CodePudding user response：

You could do something like this:

export interface IOne {
    clientId: number;
    clientName: string;
    ...
}

export interface ITwo {
    userId: number;
    userName: string;
    ...
}

const toDTO = (input: IOne): ITwo => {
  return {
    userId: input.clientId,
    userName: input.clientName
  }
}

const handleReq = (req) => {
  // we assume you have to tell Typescript what userOne is
  const userOne = req.userOne as IOne[]
  // userTwo will be typed as ITwo[] or Array<ITwo> through inference
  const userTwo = userOne.map(u => toDTO(u))
}

CodePudding user response：

A comprehensive guide to how to implement DTOs in TypeScript can be found in the following article:

https://khalilstemmler.com/articles/typescript-domain-driven-design/repository-dto-mapper/

It contains more details, but it also shows the good practices of implementing what you asked.