Returning temporary properties in GraphQL

[anirban-ray]

Suppose this is the schema:

type Actor {
    actorId: ID!
    name: String
    movies: [Movie!]! @relationship(type: "ACTED_IN", direction: OUT)
}

type Movie {
    movieId: ID!
    title: String
    description: String
    year: Int
    actors(limit: Int = 10): [Actor!]! @relationship(type: "ACTED_IN", direction: IN)
}

Now, let's suppose I want top movies with most actors. This is a solution with map projection.

type Query {
    getMoviesWithMostActors(limit: Int = 5): [Movie]
        (
            statement: """
                MATCH (movie:Movie)
                MATCH (movie) <-[act:ACTED_IN]- (:Actor)
                WITH movie, count(act) AS actorCount
                    ORDER BY actorCount DESCENDING
                    LIMIT $limit
                RETURN movie {.*, numActors: actorCount}
            """
        )
}

The query itself runs fine in Neo4j Browser, but GraphQL can't use it.

Suppose I use the following in GraphQL playground:

query {
    this_works: getMoviesWithMostActorsbase(limit: 2) {
        movieId
    }

    this_does_not_work: getMoviesWithMostActorsbase(limit: 2) {
        movieId
        numActors
    }
}

It fails with GRAPHQL_VALIDATION_FAILED.

"GraphQLError: Cannot query field \"numActors\" on type \"Movie\"."

I can extend the Movie type with a new property, but I will not need it anywhere else. Also, I have a lot of queries, and all with their specific extra properties. Also, in my actual database, there will be queries on other type of nodes too.

So, I want to know if there is a way to temporarily add a property for GraphQL to process. Or, is there a better way handle this situation in a general way (and not just this dummy example)?

I am also open to suggestions with returning a map, if it somehow avoids creation of new types in every single cases, similar to this:

type Query {
    getMoviesWithMostActors(limit: Int = 5): [Movie]
        (
            statement: """
                MATCH (movie:Movie)
                MATCH (movie) <-[act:ACTED_IN]- (:Actor)
                WITH movie, count(act) AS actorCount
                    ORDER BY actorCount DESCENDING
                    LIMIT $limit
                RETURN {movieData: movie, movieScore: actorCount}
            """
        )
}