DgsEntityFetcher optimization

[jacobo-cloudbeds]

Hi!

I'm testing GraphQL Federation with DGS and while replicating the example from the docs I realized that movie and reviewsFetcher are called N times (once per Show), but reviews could be fetched for all shows in a single query more efficiently. I guess I could use the DgsDataFetchingEnvironment to get access to the representations argument the first time movie is called, fetch all reviews for all shows, and store them in the context to return them later when reviewsFetcher is called. I wonder if there is a better/more elegant way to do it.

    @DgsEntityFetcher(name = "Show")
    public Show movie(Map<String, Object> values) {
        return new Show((String) values.get("id"), null);
    }

    @DgsData(parentType = "Show", field = "reviews")
    public List<Review> reviewsFetcher(DgsDataFetchingEnvironment dataFetchingEnvironment)  {
        Show show = dataFetchingEnvironment.getSource();
        return reviews.get(show.getId());
    }

Thanks!

[srinivasankavitha]

Have you considered using a data loader which will batch all the calls for fetching reviews. You won't be able to avoid the N calls to reviewsFetcher, but reviewsFetcher can use a dataloader which will optimize the fetching from other backends/datastores etc.

…

On Wed, Aug 31, 2022 at 6:01 AM jacobo-cloudbeds ***@***.***> wrote: Hi! I'm testing GraphQL Federation with DGS and while replicating the example from the docs I realized that movie and reviewsFetcher are called N times (once per Show), but reviews could be fetched for all shows in a single query more efficiently. I guess I could use the DgsDataFetchingEnvironment to get access to the representations argument the first time movie is called, fetch all reviews for all shows, and store them in the context to return them later when reviewsFetcher is called. I wonder if there is a better/more elegant way to do it. @DgsEntityFetcher(name = "Show") public Show movie(Map<String, Object> values) { return new Show((String) values.get("id"), null); } @DgsData(parentType = "Show", field = "reviews") public List<Review> reviewsFetcher(DgsDataFetchingEnvironment dataFetchingEnvironment) { Show show = dataFetchingEnvironment.getSource(); return reviews.get(show.getId()); } Thanks! — Reply to this email directly, view it on GitHub <#1210>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AJ5JPXMX47N2KA2Z6477QBDV35JSDANCNFSM6AAAAAAQBLK5YY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[tknupf]

Am I correct that this is still not possible?
If not I will DgsDataFetchingEnvironment.getVariables().get("representations") parse the information out of it
and store the other results in the customContext.

I will not use DataLoaders because that breaks the federation.

[srinivasankavitha]

You should be able to use a data loader to load all the results for a single field in the entity fetcher. If you need it for multiple different fields, then yes, you'll have to do what you described.

[tknupf]

O.k. so how do I return all the values for the above example?