Nested Target

[Kevin D]

In the mapstruct examples it shows how to take a nested source object and flatten it into a destination object.   Is there a way to easily reverse this so that the flattened object can be mapped back to to the nested object.

Example

SongNested {

   String songTitle

   Artist artist = {

       String artistName

   }

}

SongFlattened {

    String songTitle,

    String artistName

}

This is what I would write to get from the nested to the flattened

@Mapping(source="artist.artistName", target="artistName")
public SongFlattened toFlat(SongNested nested);

Is there a way to easily get from the flattened back to the nested?

[Gunnar Morling]

Hi Kevin,

Nesting on the target side is not supported yet.

It's a very popular request, and we've planned to look into it soon.
It's a matter of resources, essentially. The relevant issue is
https://github.com/mapstruct/mapstruct/issues/389, any help is
welcome.

--Gunnar

[Kevin Dodge]

I realize that nesting on the target side is not supported.   I was looking for how someone would do the reverse mapping without that.

If I were to do it it would look like this 

public abstract SongNested toNestedSong(SongFlattened);

public abstract ArtistNested toNextedArtist(SongFlattened);

public SongNested toNested(SongFlattened flat) {
   SongNested nested = toNestedSong(flat);

}

[Kevin Dodge]

Sorry, I accidentally posted this before I was done.

public abstract SongNested toNestedSong(SongFlattened);

public abstract ArtistNested toNextedArtist(SongFlattened);

public SongNested toNested(SongFlattened

flat) {
   SongNested nested = toNestedSong(flat);
   if (nested != null) {
      nested.setArtist(toArtistNested(flat);
   }
   return nested;
}

Is there a better way than creating an abstract class and manually nesting it myself?

[Sjaak Derksen]

As in:

https://github.com/mapstruct/mapstruct/issues/389? Working on that (already for some time)..

Best regards,

Sjaak

[Kevin D]

An alternative to nesting that would work well for me would be to allow me to specify the source of a mapping as the current source object.    So to taking my previous example I would like to be able to do this --- 

@Mapping(sourceIsCurrentSource=true, target="artist")
public SongNested toNestedSong(SongFlattened song)
public ArtistNested toNextedArtist(SongFlattened);

This would allow me to pass in my flattened object as the source to another call thereby removing my need to auto wire it as I have.    Is this currently possible?   

[Kevin D]

Doing some more trial and error it turns out I can do what I want using expressions, although I would rather if there were a clearer way

@Mapping(target="artist", expression="java(toNestedAddress(song))")

public SongNested toNestedSong(SongFlattened song)
public ArtistNested toNestedArtist(SongFlattened);

[Kevin D]

Sorry, I keep mixing up what I am working on with the example.

It should have been

@Mapping(target="artist", expression="java(toNestedArtist(song))")public SongNested toNestedSong(SongFlattened song)
public ArtistNested toNestedArtist(SongFlattened);