How to Change a Property in a Child DTO Class in NestJS with Node.js

Question

How to Change a Property in a Child DTO Class in NestJS with Node.js

I am working with enums for status:

export enum Status {
  Active = "Active",
  Inactive = "Inactive",
}

Additionally, I have a UserStatus enum:

export enum UserStatus {
  Active = Status.Active,
};

There is also a common dto that includes the status:

export class CommonDto {

  @ApiProperty({ description: "Status", required: true })
  status: Status;

In my user dto, I extend this class like so:

export class UserDto extends CommonDto {

  @ApiProperty({ description: "Status", required: true, enum: UserStatus })
  status: UserStatus;

However, there seems to be an error:

Property 'status' in type 'UserDto' is not assignable to the same property in base type 'CommonDto'.
  Type 'UserStatus' is not assignable to type 'Status'

Can anyone provide assistance?

node.js typescript oop enums nestjs

Answer 1

Answer №1

There are several approaches to addressing this issue.

The first method involves using generic classes

In this scenario, the type of the status generic is specified. This allows each class that extends from CommonDto to have its own unique status type.

export class CommonDto<T> {
  @ApiProperty({ description: "Status", required: true })
  status: T;
  // ...
}

export class UserDto extends CommonDto<UserStatus> {
  // ...
}

The second approach is utilizing union types

In TypeScript, multiple possible types can be set using union types:

export type AnyStatus = Status | UserStatus;

export class CommonDto {
  @ApiProperty({ description: "Status", required: true })
  status: AnyStatus;
  // ...
}

export class UserDto extends CommonDto {
  @ApiProperty({ description: "Status", required: true, enum: UserStatus })
  status: AnyStatus;
  // ...
}

The third option involves using intersected types

In TypeScript, properties can be "deleted" and "added" in extended classes to manipulate their types, as shown below:

type WithUserStatus<T> = Omit<T, 'status'> & { status: UserStatus };

type UserDto = WithUserStatus<CommonDto>;

Learn more about intersections here

These are potential solutions for your situation. It is recommended to define the status separately with its own type in each class (excluding the base class CommonDto).

Answer 2

There are several approaches to addressing this issue.

The first method involves using generic classes

In this scenario, the type of the status generic is specified. This allows each class that extends from CommonDto to have its own unique status type.

export class CommonDto<T> {
  @ApiProperty({ description: "Status", required: true })
  status: T;
  // ...
}

export class UserDto extends CommonDto<UserStatus> {
  // ...
}

The second approach is utilizing union types

In TypeScript, multiple possible types can be set using union types:

export type AnyStatus = Status | UserStatus;

export class CommonDto {
  @ApiProperty({ description: "Status", required: true })
  status: AnyStatus;
  // ...
}

export class UserDto extends CommonDto {
  @ApiProperty({ description: "Status", required: true, enum: UserStatus })
  status: AnyStatus;
  // ...
}

The third option involves using intersected types

In TypeScript, properties can be "deleted" and "added" in extended classes to manipulate their types, as shown below:

type WithUserStatus<T> = Omit<T, 'status'> & { status: UserStatus };

type UserDto = WithUserStatus<CommonDto>;

Learn more about intersections here

These are potential solutions for your situation. It is recommended to define the status separately with its own type in each class (excluding the base class CommonDto).

How to Change a Property in a Child DTO Class in NestJS with Node.js

Answer №1

The first method involves using generic classes

The second approach is utilizing union types

The third option involves using intersected types

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