NestJS Mapped Typed - Nested objects - swagger

Question

In NestJS I want to use PickType() with a class, which has nested class properties.
Example:
export class Product {
status: string;
payment: {
status: string;
type: string;
}
}
It should result in the swagger documentation as following DTO:
class PartialClass {
payment: {
status: string,
type: string
}
}
But the following implementation does not work:
class PartialClass {
#ApiProperty({
type: () => PickType(Videochat, ['payment']),
})
payment: Pick<Videochat['payment'], 'type' | 'status'>;
}
It returns an empty payment class property:
class PartialClass {
payment: {
}
}
So i guess PickType can't handle nested Types.
I tried also:
type: () => PickType(PickType(Videochat, ['payment']), ['status', 'type'])
but it also not working.

Answer 1

You can handle it this way, let's assume we have the following class:
type User = {
id: number,
name: string,
address: {
street: string,
zipcode: string,
geo: {
lat: string,
lng: string,
},
},
};
to pick user with address you can simply do type UserWithOnlyAddress = Pick<User, 'address'>;
in case you have to pick user with address's street only you can handle it:
type Pick2<T, K1 extends keyof T, K2 extends keyof T[K1]> = {
[P1 in K1]: {
[P2 in K2]: (T[K1])[P2];
};
};
type UserWithOnlyStreetAddress = Pick2<User, 'address', 'street'>;
And for picking at three levels
type UserWithOnlyGeoLat = Pick3<User, 'address', 'geo', 'lat'>;
type User = {
id: number,
name: string,
address: {
street: string,
zipcode: string,
geo: {
lat: string,
lng: string,
},
},
};
type Pick3<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2]> = {
[P1 in K1]: {
[P2 in K2]: {
[P3 in K3]: ((T[K1])[K2])[P3];
};
};
};