Classes strategy

Discover TypeScript class metadata with decorators or generated metadata factories.

@automapper/classes maps TypeScript and JavaScript classes. It reads metadata created by @AutoMap() or the optional transformer plugin.

npm install @automapper/core @automapper/classes reflect-metadata

pnpm add @automapper/core @automapper/classes reflect-metadata

bun add @automapper/core @automapper/classes reflect-metadata

import 'reflect-metadata';
import { AutoMap, classes } from '@automapper/classes';
import { createMapper } from '@automapper/core';

const mapper = createMapper({ strategyInitializer: classes() });

AutoMap metadata

Use @AutoMap() when emitted design metadata identifies a primitive or Date. Supply an explicit callback for nested models, arrays, enums, unions, and ambiguous types.

enum Role {
  Admin = 'admin',
  User = 'user',
}

class User {
  @AutoMap()
  name!: string;

  @AutoMap(() => String)
  role!: Role;

  @AutoMap(() => Profile)
  profile!: Profile;

  @AutoMap(() => [Date])
  logins!: Date[];
}

Array metadata wraps the element identifier in an array: () => [Profile].

Circular models

Nested metadata defaults to depth 1. Use the options form when a circular relationship should traverse further:

class User {
  @AutoMap({ type: () => Organization, depth: 2 })
  organization!: Organization;
}

Keep depth bounded so circular graphs terminate.

Class identifiers in v9

Abstract classes and classes with non-public constructors can be used as runtime identifiers. If such a destination cannot be instantiated by the default strategy, provide constructUsing() for that mapping or a custom destinationConstructor in the strategy options.

Decoratorless options

• Use autoMap() for a few same-name members.
• Use the transformer plugin to emit metadata for whole model files.
• Use mapped types to derive pick, omit, and intersection classes while retaining metadata.