How to create dto of an complex object in NestJs

I’m a beginner at NestJs and I want to create a dto of the following struct:

I want to create an API that can return this object using DTOs.

export let Week = [
    {
        DayName : "TuesDay",
        TimeZone: [
            {
                First: {
                        Start: 18,
                        end: 19,
                        isReserved: false,
                        reserver: "someone"
                },
                Second: {
                        Start: 19,
                        end: 20,
                        isReserved: false,
                        reserver: "someone"
                },
                Third: {
                        Start: 20,
                        end: 21,
                        isReserved: false,
                        reserver: "someone"
                }
            }
        ]
    },
    {
        DayName : "Wednesday",
        TimeZone: [
            {
                First: {
                        Start: 18,
                        end: 19,
                        isReserved: false,
                        reserver: "someone"
                },
                Second: {
                        Start: 19,
                        end: 20,
                        isReserved: false,
                        reserver: "someone"
                },
                Third: {
                        Start: 20,
                        end: 21,
                        isReserved: false,
                        reserver: "someone"
                }
            }
        ]
    },
    {
        DayName : "Friday",
        TimeZone: [
            {
                First: {
                        Start: 18,
                        end: 19,
                        isReserved: false,
                        reserver: "someone"
                },
                Second: {
                        Start: 19,
                        end: 20,
                        isReserved: false,
                        reserver: "someone"
                },
                Third: {
                        Start: 20,
                        end: 21,
                        isReserved: false,
                        reserver: "someone"
                }
            }
        ]
    }
]

I tried the following dto but I got an error in the service provider :

I create 3 classes OneSessionResponseDto, SessionsResponseDto, and WeekResponseDto so I can use them as a dto of the object above.

export class OneSessionResponseDto {
    start: number;
    end: number;
    isReserved: boolean;
    reserver: string;
}

export class SessionsResponseDto {
    First: OneSessionResponseDto;
    Second: OneSessionResponseDto;
    Third: OneSessionResponseDto;
}

export class WeekResponseDto {
    DayName: string;
    TimeZone: SessionsResponseDto;
}

this is the service provider class:

@Injectable()
export class AppService {
    private week = Week;
    getWeek() : WeekResponseDto[] {
        return (this.week); <= the error
    }
}

I got this error here:

is missing the following properties from type ‘SessionsResponseDto’: First, Second, Third

Answer

You almost have it. You need to set TimeZone‘s type to SessionsResponseDto[] because it’s an array. Then change OneSessionResponseDto#start to OneSessionResponseDto#Start (the capitalization is important). You can see a working solution in the typoescript playground here