How to Inherit or Extend typeDefs in GraphQL

Question

I have a type User. Users can also be a type TeamMember. The only difference between a User and TeamMember is an added field teamRole: String. So, I’d love to do something like the following to avoid having to redundantly define all the user's fields…

  type User {
    id: ID!,
    name: String,
    (many other field defs)
  }

  type TeamMember extends User  {
    teamRole: String,
  }

Anyone aware of a syntax for this? I thought extend would be the answer, but it seems more like javascript’s prototype

Answer 1

extend is great if you have a base schema and want to build two or more usable schemas based on it. You can, for example, define a root Query type with queries shared by all schemas, and then extend it within each individual schema to add queries specific to that schema. It's meant as a mechanism to add functionality to existing types, rather than creating new types.

GraphQL does not inherently support inheritance. There is a library out there, however, that does add this functionality, if you're using GraphQL-JS. Link here. It adds both generic types and a way for types to inherit from another type.