How to specify a default value for a boolean field using MapStruct

Question

How can you specify a defaultValue when mapping a DTO using MapStruct? The following constructs did not work

@Mapping(target = "used", defaultValue = "0")
MyDTO toDto(MyEntity entity);

@Mapping(target = "used", defaultValue = "false")
MyDTO toDto(MyEntity entity);

The documentation shows examples for all types except booleans

Answer 1

To be able to use defaultValue, you must specify a source. If the source is null then it will use the defaultValue defined.

To always assign a specific value to the target, in your case zero or false, you should then use constant instead.

More info on Default values and constants