Missing fields in DataFetchingEnvironment

[FidasL]

Hello
I am not sure if this is question for you or better for graphql-java. But let's have this example of GraphQL Resolver implementation:

@GraphQLDescription("An object with globally unique ID")
interface Node {
    val nodeID: ID
}

data class PersonNode(override val nodeID: ID, val age: Int, val address: String): Node
data class AnimalNode(override val nodeID: ID, val name: String): Node


class MyQuery {
    fun node(env: DataFetchingEnvironment, id: ID): Node {
        return if (decodeId(id) == something) {
            ...fetch object by id query param

            AnimalNode(id, "my dog's name")
        } else {
            ...fetch object by id query param

            PersonNode(id, 10, "address")
        }
    }
}

If I call query like this:

query {
  node(id: "base64") {
    ... on PersonNode {
      address
      age
    }
  }
}

when calling env.selectionSet.fields in node() function, I am not able to get specified fields from graphql request. It is important in my use-case, because I want to query from database only those columns which client specified.. My question is if there is any way to distinguish which fields client wants to query?

[samuelAndalon]

Hello, what is the result of env.selectionSet.fields when you call it in your function ?
based on the documentation of graphql-java the DataFetchingFieldSelectionSet does actually takes the fields from fragments and "flatten" them into a list

check https://github.com/graphql-java/graphql-java/blob/master/src/test/groovy/graphql/schema/DataFetchingFieldSelectionSetImplTest.groovy#L452

[FidasL]

It is an empty list (see image bellow). But I have got older versions -> graphql-kotlin:3.7.0 and graphql-java:15.0 . Not sure if there weren't some bugs..

[samuelAndalon]

yes, you are using a very old version of both graphql-java and graphql-kotlin, try updating graphql-kotlin to latest

[FidasL]

It is not so easy to bump versions in our large graphql project. I just wasn't sure why selectionSet doesn't contain selected fields if I use interface in Graphql schema. If I query data directly for specific class, selectionSet contains fields specified in request.

[dariuszkuc]

By "interface" you mean fragments? Unsure about the DataFetchingFieldSelectionSet but regular selection set makes a distinction between Fields and FragmentSpread/InlineFragment. You could check with https://github.com/graphql-java/graphql-java whether they have any insights.

That being said those lib versions are very old and unsupported anymore so would highly recommend to look into update path.