Entities that reference each other.

[Davenporten]

This question might be really dumb, I'm just trying to wrap my head around how federation works (I'm also relatively new to GraphQL, but have a little experience).

So in the video where you used this repo astronauts.js never references Mission as an external entity, rather, to be able to get missions from an Astronaut you have

  Astronaut: {
    async missions(astronaut) {
      const res = await fetch(`${apiUrl}/missions`);
      const missions = await res.json();

      return missions.filter(({ crew }) =>
        crew.includes(parseInt(astronaut.id))
      );
    }
  },

a direct call to the missions server and filtering through the result. My question is, why couldn't you do something like this in astronaut.js

    extend type Mission @key(fields: "id") {
        id: ID! @external
        crew: [Astronaut]
    }

along with all the appropriate resolver and changes in missions.js to make make it so the direct query and filtering aren't necessary. I tried this and was just getting back entities like { __typename: 'Mission', id: 2} so I know it doesn't work, but I don't understand why it doesn't work.

I hope these questions make sense. Thanks so much for your help!