Jackson and REST Android Annotations: Deserialize JSON Array of Objects

Question

I have a REST service which returns data that looks like this:

[
    { bookmark object json here },
    { bookmark object json here },
    { bookmark object json here },
    ...
]

My REST client class looks like this:

@Rest(rootUrl = Constants.ApiConfig.API_ROOT, converters = {MappingJackson2HttpMessageConverter.class})
public interface RestApiClient {
    @Get("/bookmark/read?id={identifier}")
    public BookmarkList getBookmarks(String identifier);
}

BookmarkList looks like this:

public class BookmarkList {
    List<Bookmark> bookmarks;

    @JsonValue
    public List<Bookmark> getBookmarks() {
        return bookmarks;
    }

    @JsonCreator
    public void BookmarkList(@NotNull List<Bookmark> bookmarks) {
        this.bookmarks = bookmarks;
    }
}

However, when I utilize this setup, I get the following error:

Could not read JSON: Can not deserialize instance of com.whatever.entity.BookmarkList out of START_ARRAY token

What I want is something like the EventList example at https://github.com/excilys/androidannotations/wiki/Rest-API#get, but that doesn't seem to work for me out of the box.

Is there a way to get this working?

Answer 1

Ho... We have to update this part of documentation. The wrapper solution works but doesn't fit APIs.

If you're looking at the generated code for @Get("url") MyReturnedType testService(), you should see something like this :

return restTemplate.exchange(rootUrl.concat("url"), //
    HttpMethod.GET, //
    null, //
    MyReturnedType.class, //
    urlVariables)//
  .getBody();

The returned class is injected as a parameter of exchange call. In case of generics collection (like List<MyReturnedType>), we can't inject List.class because of type checking in the return of exchange method.

However, you should be able to use this little trick in your @Rest annotated method :

public class BookmarkList extends List<Bookmark> {
}