UndefinedSubstitution

Call undefinedSubstitution() and pass in a raw value to map to the configured property in the case of the same property on Source is undefined. If we pass in an object, AutoMapper will map the object as-is without any consideration for nested mapping.

info

AutoMapper uses strict equality check against undefined (=== undefined) to make the comparison. Hence, null value will not be substituted.

createMap(
    mapper,
    User,
    UserDto,
    forMember(
        (destination) => destination.fullName,
        undefinedSubstitution('raw value')
    )
);

mapper.map({}, User, UserDto); // UserDto { fullName: 'raw value' }

undefinedSubstitution() sets the TransformationType to TransformationType.UndefinedSubstitution