Support for multiple @key directives

[Jacob Marshall]

It would be great to have support for multiple @key directives.

For reference, I'm trying to get something like the following working...

Entity service

interface Entity {
  entityRef: String!
}

extends type Query {
  entity(ref: String!): Entity
}

User service

interface Entity {
  entityRef: String!
}

type User @key(fields: "id") @key(fields: "entityRef") {
  id: ID!
  entityRef: String!
  name: String
}

extend type Query {
  me: User
}

The problem is that the first @key directive is functional. The second one is completely ignored (it took me longer than I would like to admit to figure out why this wasn't working 🤦‍♂️). This means that when the "Entity service" returns a reference to a User, it must provide an id. But the idea for this setup is to let the "User service" figure out how to resolve the User based on the "entityRef".

I'm fairly certain I can work around this for now - simply because my current implementation of generating the "entityRef" involves serialising the ID anyway. But this, I imagine, would be a nice to have for others that don't have that option.

[Matteo Collina]

Multiple @key directives are not supported atm. Would you like to send a PR?

[Jacob Marshall]

I'm going to have a go - but I'll be honest, I'm not entirely sure where to start. It also appears that my workaround won't... well... work. So attempting to add multiple @key directives is probably my best bet at this time.

[Matteo Collina]

happy to review the change!