Default for a null @MappingTarget value?

[Zachary Canann]

If the target of a @MappingTarget annotation is null, is there a MapStruct feature that can be used to instantiate the object automatically?

We are trying to use MapStruct to update an existing object, where some of the sub-objects in the hierarchy may be set to null.

[Gunnar Morling]

I don't think update methods would instantiate any missing objects
right now. It seems a reasonable option, though, maybe controlled via
a new property on @MappingTarget?

Sjaak et al., WDYT?

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[Andreas Gudian]

Well, on non-iterable properties, any "null" targets properties are created before calling the property mapping method for it.

For example (taken from one of our tests):

        if ( source.getCompany() != null ) {
            if ( target.getCompany() == null ) {
                target.setCompany( new CompanyEntity() );
            }
            toCompanyEntity( source.getCompany(), target.getCompany() );
        }
        else {
            target.setCompany( null );
        }

Limitation: iterables and maps behave differently here, as we don't call property mapping methods with those types as @MappingTarget. So any updating logic would break below such property paths. The main reason for that is that we didn't yet came up with a clean solution to identify what elements in those collections need to be removed, created, or updated by the incoming source elements...

@Sjaak, did I miss something?

2016-12-23 8:34 GMT+01:00 Gunnar Morling <gun...@hibernate.org>:

I don't think update methods would instantiate any missing objects
right now. It seems a reasonable option, though, maybe controlled via
a new property on @MappingTarget?

Sjaak et al., WDYT?

2016-12-23 0:45 GMT+01:00 Zachary Canann <zachar...@gmail.com>:
> If the target of a @MappingTarget annotation is null, is there a MapStruct
> feature that can be used to instantiate the object automatically?
>
> We are trying to use MapStruct to update an existing object, where some of
> the sub-objects in the hierarchy may be set to null.
>
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