NullSubstitution

Call nullSubstitution() and pass in a raw value to map to the configured property in the case of the same property on Source is null. 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 null (=== null) to make the comparison. Hence, undefined value will not be substituted.

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

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

nullSubstitution() sets the TransformationType to TransformationType.NullSubstitution