Creating Custom Data Classes

FP can be extended to represent your own data.

For general data, you should extend NonData - the name is misleading, but represents successful data that does not extend the Data class.

src/user/dto/user-details.ts

import { NonData } from "@formulaic/fp";
import { ApiProperty, ApiPropertyOptional } from "@nestjs/swagger";
import { Expose } from "class-transformer";
import { Equals, IsString } from "class-validator";
import { User } from "../user.entity"; (1)

export class UserDetails<T = any> extends NonData<T> {
  public static readonly kind = "UserDetails";

  @ApiProperty()
  @Equals("UserDetails")
  @Expose()
  public override readonly kind: "UserDetails";

  @ApiProperty()
  @Expose()
  public override readonly status: 200 | 201;

  @ApiProperty()
  @IsString()
  @Expose()
  public readonly id: string;

  @ApiPropertyOptional()
  @IsString()
  @Expose()
  public readonly name: string;

  public constructor(user: User, created = false) {
    super();
    this.kind = "UserDetails";
    this.status = created ? 201 : 200;
    this.id = user.id;
    this.name = user.name;
  }

}

1	The `User` TypeORM entity was created in Formulaic’s entity-service documentation

You likely will want to add additional properties to the object, and add constructor parameters to set them.

FP Utility Methods