[interface] how to return an interface in data-fetcher?

[jessepinkman9900]

Hi,
I'm working with a graphql schema that has interfaces. I'm having trouble returning them in the data-fetcher.
Looking for a worked-out example.
Getting this error in spring logs when I try to execute query in graphiql:

graphql.AssertException: You have asked for named object type 'Entity' but its not an object type but rather a 'graphql.schema.GraphQLInterfaceType'

I have read: https://netflix.github.io/dgs/advanced/type-resolvers-for-abstract-types/

# original schema
type Query {
    movies: [Movie]
}

interface Movie {
    title: String
}

type ScaryMovie implements Movie {
    title: String
    gory: Boolean
    scareFactor: Int
}

type ActionMovie implements Movie {
    title: String
    nrOfExplosions: Int
}

@DgsComponent
public class MovieDataFetcher {
    @DgsData(parentType = "Query", field = "movies")
    public List<Movie> movies() {
        return Lists.newArrayList(
                new ActionMovie("Crouching Tiger", 0),
                new ActionMovie("Black hawk down", 10),
                new ScaryMovie("American Horror Story", true, 10),
                new ScaryMovie("Love Death + Robots", false, 4)
            );
    }
}

They have solved for a case when the interface has ONLY ONE attrribute, i.e title in case for interface Movie

@DgsTypeResolver(name = "Movie")
public String resolveMovie(Movie movie) {
    if(movie instanceof ScaryMovie) {
        return "ScaryMovie";
    } else if(movie instanceof ActionMovie) {
        return "ActionMovie";
    } else {
        throw new RuntimeException("Invalid type: " + movie.getClass().getName() + " found in MovieTypeResolver");
    }
}

Looking for a solution where Movie had more than one attribute.
For example IF schema was

# example schema
type Query {
    movies: [Movie]
}

interface Movie {
    title: String
    year: Int
    director: String
}

type ScaryMovie implements Movie {
    title: String
    gory: Boolean
    scareFactor: Int
}

type ActionMovie implements Movie {
    title: String
    nrOfExplosions: Int
}

THEN what would the resulting @DgsData or @DgsTypeResolver be?

[srinivasankavitha]

The DgsTypeResolver would stay the same. The types ActionMovie and ScaryMovie would define the additional fields, i.e, year and director ( title is already there). The datafetcher can create an instance of either ActionMovie or ScaryMovie with the additional fields populated by the same datafetcher. You can also define field specific data fetchers if you are not able to populate all the fields in the same movies data fetcher. graphql-java will take care of calling every data fetcher for the fields you specify. Hope that helps.

…

On Mar 13, 2021, at 10:38 AM, Srinivas Kota ***@***.***> wrote:  Hi, I'm working with a graphql schema that has interfaces. I'm having trouble returning them in the data-fetcher. Looking for a worked-out example. I have read: https://netflix.github.io/dgs/advanced/type-resolvers-for-abstract-types/ # original schema type Query { movies: [Movie] } interface Movie { title: String } type ScaryMovie implements Movie { title: String gory: Boolean scareFactor: Int } type ActionMovie implements Movie { title: String nrOfExplosions: Int } @DgsComponent public class MovieDataFetcher { @DgsData(parentType = "Query", field = "movies") public List<Movie> movies() { return Lists.newArrayList( new ActionMovie("Crouching Tiger", 0), new ActionMovie("Black hawk down", 10), new ScaryMovie("American Horror Story", true, 10), new ScaryMovie("Love Death + Robots", false, 4) ); } } They have solved for a case when the interface has ONLY ONE attrribute, i.e title in case for interface Movie @DgsTypeResolver(name = "Movie") public String resolveMovie(Movie movie) { if(movie instanceof ScaryMovie) { return "ScaryMovie"; } else if(movie instanceof ActionMovie) { return "ActionMovie"; } else { throw new RuntimeException("Invalid type: " + movie.getClass().getName() + " found in MovieTypeResolver"); } } Looking for a solution where Movie had more than one attribute. For example IF schema was # example schema type Query { movies: [Movie] } interface Movie { title: String year: Int director: String } type ScaryMovie implements Movie { title: String gory: Boolean scareFactor: Int } type ActionMovie implements Movie { title: String nrOfExplosions: Int } THEN what would the resulting @DgsData or @DgsTypeResolver be? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or unsubscribe.

[jessepinkman9900]

This works. Thank you! :)