MyLittleSuite/dart_mapperdart_mapper

@Mapper

Marks an abstract class for dart_mapper code generation.

@Mapper

Marks an abstract class for code generation. dart_mapper generates a concrete implementation class containing all declared mapping methods.

Signature

const Mapper({
  String implementationName = '<CLASS_NAME>Impl',
  Set<Object>? uses,
})

Parameters

ParameterTypeDefaultDescription
implementationNameString'<CLASS_NAME>Impl'The name for the generated implementation class. Use <CLASS_NAME> as a placeholder for the annotated class name.
usesSet<Object>?nullA set of external mapper types to inject. The generated class will accept these as constructor parameters and delegate to them for nested object conversion.

Basic Usage

import 'package:dart_mapper/dart_mapper.dart';
part 'user_mapper.g.dart';

@Mapper()
abstract class UserMapper {
  UserDto toDto(User user);
  User fromDto(UserDto dto);
}

The part directive is required. The generator writes the implementation into the .g.dart file.

Custom Implementation Name

Use implementationName to override the default <ClassName>Impl naming:

@Mapper(implementationName: 'UserMapperImpl')
abstract class UserMapper {
  UserDto toDto(User user);
}

The <CLASS_NAME> token is replaced with the annotated class name at generation time:

// Generates: class UserMapperTypeMapper extends UserMapper
@Mapper(implementationName: '<CLASS_NAME>TypeMapper')
abstract class UserMapper { ... }

<CLASS_NAME> resolves to the annotated class name (UserMapper), so the generated class is UserMapperTypeMapper.

External Mapper Injection

Use uses to compose mappers. The generator injects the listed mappers as required constructor parameters:

@Mapper()
abstract class AddressMapper {
  AddressDto toDto(Address address);
}

// UserMapper delegates nested Address conversion to AddressMapper
@Mapper(uses: {AddressMapper})
abstract class UserMapper {
  UserDto toDto(User user);
}

Generated:

class UserMapperImpl extends UserMapper {
  UserMapperImpl({required this.addressMapper});

  final AddressMapper addressMapper;

  @override
  UserDto toDto(User user) {
    return UserDto(
      user.name,
      addressMapper.toDto(user.address),
    );
  }
}

Instantiate with dependency injection or manually:

final addressMapper = AddressMapperImpl();
final userMapper = UserMapperImpl(addressMapper: addressMapper);

Requirements

  • The annotated class must be abstract.
  • The file must include part '<filename>.g.dart';.
  • The generator creates one .g.dart file per source file containing @Mapper.

See Also

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Getting Started
@Mapping