Nested Resolvers and Shared Arguments

There are a few ways in which shared arguments can be accessed from different resolver levels. Say we have the following schema:

type Query {
  findUser(id: String!): User
}

type User {
  photos(numberOfPhotos: Int!): [Photo!]!
}

type Photo {
  url: String!
}

In Kotlin code, when we are resolving photos, if we want access to the parent field findUser and its arguments there are a couple ways we can access it:

DataFetchingEnvironment

You can add the DataFetchingEnvironment as an argument. This class will be ignored by the schema generator and will allow you to view the entire query sent to the server. See more in the DataFetchingEnvironment documentation

class User {
    fun photos(environment: DataFetchingEnvironment, numberOfPhotos: Int): List<Photo> {
      val username = environment.executionStepInfo.parent.arguments["id"]
      return getPhotosFromDataSource(username, numberOfPhotos)
    }
}

GraphQL Context

You can add the GraphQLContext as an argument. This class will be ignored by the schema generator and will allow you to view the context object you set up in the data fetchers. See more in the GraphQLContext documentation

class User {
    fun photos(context: MyContextObject, numberOfPhotos: Int): List<Photo> {
      val userId = context.getDataFromMyCustomFunction()
      return getPhotosFromDataSource(userId, numberOfPhotos)
    }
}

Excluding Arguments from the Schema

You can construct the child objects by passing down arguments as non-public fields or annotate the argument with @GraphQLIgnore

class User(private val userId: String) {

    fun photosProperty(numberOfPhotos: Int): List<Photo> {
      return getPhotosFromDataSource(userId, numberOfPhotos)
    }

    fun photosIgnore(@GraphQLIgnore userId: String, numberOfPhotos: Int): List<Photo> {
      return getPhotosFromDataSource(userId, numberOfPhotos)
    }
}

Spring Integration

See Writing Schemas with Spring for integration details.