forMember

Select a destination path and assign one member-mapping function, with an optional precondition.

forMember() targets one destination member and assigns its transformation:

The callbacks are contextually typed from the source and destination passed to createMap().

createMap<User, UserDto>(mapper: Mapper, source: ModelIdentifier<User>, destination: ModelIdentifier<UserDto>, ...mappingConfigFns: (MappingConfiguration<User, UserDto> | undefined)[]): Mapping<User, UserDto> (+1 overload)createMap(
  const mapper: Mappermapper,
  class UserUser,
  class UserDtoUserDto,
  forMember<User, UserDto, string>(selector: Selector<UserDto, string>, preCondOrMapMemberFn: PreConditionReturn<User, UserDto, string> | MemberMapReturn<User, UserDto, string> | undefined, mapMemberFn?: MemberMapReturn<User, UserDto, string> | undefined): MappingConfiguration<User, UserDto>forMember(
    (
destination: UserDtodestination) => destination: UserDtodestination.UserDto.fullName: stringfullName,


    mapFrom<User, UserDto, string>(from: ((source: User) => MaybePromise<string>) | Resolver<User, UserDto, string>): MapFromReturn<User, UserDto, string>mapFrom((
source: Usersource) => `${source: Usersource.User.firstName: stringfirstName} ${source: Usersource.User.lastName: stringlastName}`),


  ),
);

The destination selector is strongly typed. The second argument determines how AutoMapper produces that value.

Precondition

Add preCondition() before the member function to skip its work unless a source predicate succeeds. An optional default is assigned when the predicate fails.

forMember(
  (destination) => destination.fullName,
  preCondition((source) => source.visible, "Hidden user"),
  mapFrom((source) => `${source.firstName} ${source.lastName}`),
);

Use custom members for exceptions to convention. If almost every destination path needs one, an explicit transformation may be easier to understand.