Defines a GraphQL interface type with a clean DSL.

Usage

defmodule MyApp.GraphQL.Interfaces.Node do
  use GreenFairy.Interface

  interface "Node" do
    @desc "A globally unique identifier"
    field :id, :id, null: false
  end
end

The resolve_type function is automatically generated based on types that implement this interface using implements/1. Each implementing type must specify its backing struct via type "Name", struct: Module.

Manual resolve_type

You can override the auto-generated resolve_type if needed:

interface "Node" do
  field :id, :id, null: false

  resolve_type fn
    %MyApp.User{} -> :user
    %MyApp.Post{} -> :post
    _ -> nil
  end
end