What is the best way to associate an HTTP request response with a specific object in TypeScript?

Question

What is the best way to associate an HTTP request response with a specific object in TypeScript?

I'm currently learning Angular, TypeScript, and RxJS. I have an HTTP request that retrieves a JSON response. Within this JSON response, there is data that I need to use to create a specific object. Let's assume that the object I want to create looks like this:

export class RegularUser {
    constructor(
        public id: number,
        public firstName: string,
        public lastName: string,
        public token: string
    ) {}
}

Now, when I make a request to an API, the data is returned in the following format:

{
    success: boolean,
    uid: number,
    first_name: string,
    last_name: string,
    cid: number,
    rights: number[],
    token: string
}

Since I am using the HttpClient service, my initial thought was to do the following:

this.httpClient.get(
    'http://api.example.com/api/get_user'
).pipe(
    tap((receivedData: Response) => console.log(receivedData)),
    map((receivedData: Response) => {
        return new RegularUser(
            receivedData.uid, 
            receivedData.first_name, 
            receivedData.last_name, 
            receivedData.token);
    })
);

However, in TypeScript, the receivedData object does not contain the properties listed above. Should I create an interface for the API response and then map it to my RegularUser object?

angular typescript interface rxjs

Answer 1

Answer №1

When using the type parameter in the get() method, it is possible to define an interface. In some cases, an additional interface might be necessary to separate concerns in your specific scenario. The reason for this is that using get() with a type will not instantiate a new object of the class RegularUser. By creating an intermediary or additional interface with the expected properties from the server response, you can then use it to create an instance of your final class:

interface Foo {
  uid: number,
  first_name: string,
  last_name: string,
  token: string
}

this.httpClient.get<Foo>(
    'http://api.example.com/api/get_user'
).pipe(
    tap((receivedData: Foo) => console.log(receivedData)),
    map((receivedData: Foo) => {
        return new RegularUser(
            receivedData.uid, 
            receivedData.first_name, 
            receivedData.last_name, 
            receivedData.token);
    })
);

If you do not require an actual instance of the RegularUser class, you can simply define it as an interface or class with properties:

this.httpClient.get<RegularUser>(
    'http://api.example.com/api/get_user'
).pipe(
    tap((receivedData: RegularUser) => console.log(receivedData))
);

Hopefully this explanation clarifies the situation!

Answer 2

When using the type parameter in the get() method, it is possible to define an interface. In some cases, an additional interface might be necessary to separate concerns in your specific scenario. The reason for this is that using get() with a type will not instantiate a new object of the class RegularUser. By creating an intermediary or additional interface with the expected properties from the server response, you can then use it to create an instance of your final class:

interface Foo {
  uid: number,
  first_name: string,
  last_name: string,
  token: string
}

this.httpClient.get<Foo>(
    'http://api.example.com/api/get_user'
).pipe(
    tap((receivedData: Foo) => console.log(receivedData)),
    map((receivedData: Foo) => {
        return new RegularUser(
            receivedData.uid, 
            receivedData.first_name, 
            receivedData.last_name, 
            receivedData.token);
    })
);

If you do not require an actual instance of the RegularUser class, you can simply define it as an interface or class with properties:

this.httpClient.get<RegularUser>(
    'http://api.example.com/api/get_user'
).pipe(
    tap((receivedData: RegularUser) => console.log(receivedData))
);

Hopefully this explanation clarifies the situation!

Answer 3

Answer №2

A more effective approach would be to utilize an interface instead of a constructor. By employing an interface, developers can leverage the Language Service in their IDE to benefit from code autocompletion and avoid errors related to property naming.

export interface UserCredentials {
    valid: boolean;
    id: number;
    first: string;
    last: string;
    company_id: number;
    permissions: number[];
    access_token: string;
}

Within a service component:

this.httpClient.get<UserCredentials>(
    'http://api.example.com/api/get_user'
).pipe(
    tap((data: UserCredentials) => console.log(data))
);

Answer 4

A more effective approach would be to utilize an interface instead of a constructor. By employing an interface, developers can leverage the Language Service in their IDE to benefit from code autocompletion and avoid errors related to property naming.

export interface UserCredentials {
    valid: boolean;
    id: number;
    first: string;
    last: string;
    company_id: number;
    permissions: number[];
    access_token: string;
}

Within a service component:

this.httpClient.get<UserCredentials>(
    'http://api.example.com/api/get_user'
).pipe(
    tap((data: UserCredentials) => console.log(data))
);

Answer 5

Answer №3

To customize your own Response interface, follow these steps:

export interface CustomResponse {
  success: boolean,
  uid: number,
  first_name: string,
  last_name: string,
  cid: number,
  rights: number[]
  token: string
}

After creating the interface, import it into your service:

import { CustomResponse } from '../some/path/filename.ts';

If preferred, you can include it directly in your service without the need for 'export'.

Simply use the CustomResponse interface just like the existing Response interface:

(receivedData: CustomResponse)

Note: Feel free to choose any name for the interface (with TitleCase for consistency). Avoid using names already in use by Angular to prevent conflicts. Refer to comments for more details.

It might be necessary to make certain properties optional using ?: to prevent 'some properties are missing' warnings if not all are utilized:

...
success?: boolean,
...

Alternatively, you can eliminate the warning by defining the type as any, but this approach is not recommended:

(receivedData: any)

Answer 6

To customize your own Response interface, follow these steps:

export interface CustomResponse {
  success: boolean,
  uid: number,
  first_name: string,
  last_name: string,
  cid: number,
  rights: number[]
  token: string
}

After creating the interface, import it into your service:

import { CustomResponse } from '../some/path/filename.ts';

If preferred, you can include it directly in your service without the need for 'export'.

Simply use the CustomResponse interface just like the existing Response interface:

(receivedData: CustomResponse)

Note: Feel free to choose any name for the interface (with TitleCase for consistency). Avoid using names already in use by Angular to prevent conflicts. Refer to comments for more details.

It might be necessary to make certain properties optional using ?: to prevent 'some properties are missing' warnings if not all are utilized:

...
success?: boolean,
...

Alternatively, you can eliminate the warning by defining the type as any, but this approach is not recommended:

(receivedData: any)

What is the best way to associate an HTTP request response with a specific object in TypeScript?

Answer №1

Answer №2

Answer №3

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