I have normal method Request(method: HttpMethod, url: string, ...) for calling API. I am using TypeScript.
I need to transform response from this API Request into class instance with class-transformer (or without it :D).
Example:
class UserResponse {
id: number;l
foo: string;
bar: string;
}
const user = await Request(HttpMEthod.GET, '/user/1');
// `user` should be class instance `UserResponse`
I know I cannot use generics like so:
const Request = <T>(method: HttpMethod, url: string, ...) => {
// axios or something else...
return plainToClass(T, res);
}
const user = await Request<UserResponse>(HttpMEthod.GET, '/user/1');
Generics do not work that way, but I can do something like:
const Request = <T>(method: HttpMethod, url: string, ..., transformTo?: { new (): T }) => {
// axios or something else...
return plainToClass(transformTo, res);
}
const user = await Request(HttpMEthod.GET, '/user/1', ... , new UserResponse());
But this also not working. I am still getting user type:
const user: unknown
What I am doing wrong?
First and foremost, what is Request? I am assuming this returns a Promise.
You have a couple of issues:
new UserResponseinterface where it's more a data contract rather than a full initialized class.Here is how you need to do this:
class UserResponse {
public id: number;
public foo: string;
public bar: string;
constructor(user: UserResponse) {
Object.assign(this, user); // or set each prop individually
}
}
const response = await Request(HttpMEthod.GET, '/user/1');
const user = new UserResponse(response);Basically, you need to add a constructor to your class (otherwise, just use an interface). Once you've got the constructor, then you can new up a new UserResponse class from the response.
Also, if Request looks like:
const Request = <T>(method: HttpMethod, url: string, ..., transformTo?: { new (): T }) => {
// axios or something else...
return plainToClass(transformTo, res);
}
I think you want to do this instead: const user = await Request(HttpMEthod.GET, '/user/1', ... , UserResponse);
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