Apollo Federation Referencing Test

This example tries to find a solution to reference an interface of another service in a Federated GraphQL schema. We have a project service with a Project interface and two implementations (SoftwareDevelopmentProject and MarketingProject) and a rights service, that just holds IDs of accessible projects and tries to reference the projectsIds of the project service.

Starting the example

Just call

yarn install
yarn start-rights-service
yarn start-project-service
yarn start-gateway-service

The goal

The main goal is that we can execute a query like (e.g. finally get the nicename from the Gateway, not only the ID...)

query myUser {
  user {
    id
    name
    accessibleProjects {
      id
      niceName
    }
  }
}

Current problem

However it still does not work yet (we only get an array of null). The Gateway collects the accessible projects and their specific type in the rights service and then calls the project service with the interface (...on Project), but without any representations given, so the projects service does have no chance to deliver anything.

Log-Output:

Query:
"query($representations:[_Any!]!){_entities(representations:$representations){...on Project{niceName}}}"


Variables:
{
  "representations": []
}

Other context

Yes, you might notice that we have to know every interface implementation in the rights service. This is also described in this Github issue, but not part of this problem description. If there is a solution to get rid of this fact, that would be even better...

Any input to find a solution here helps ;-) !