A defined interface type that represent a list of named fields and their arguments.

Fields on an interface have the same rules as fields on an Absinthe.Type.Object.

If an Absinthe.Type.Object lists an interface in its :interfaces entry, it it guarantees that it defines the same fields and arguments that the interface does.

Because sometimes it’s for the interface to determine the implementing type of a resolved object, you must either:

• Provide a :resolve_type function on the interface
• Provide a :is_type_of function on each implementing type

interface :named_entity do
  field :name, :string
  resolve_type fn
    %{age: _}, _ -> {:ok, :person}
    %{employee_count: _}, _ -> {:ok, :business}
    _ -> :error
  end
end

object :person do
  field :name, :string
  field :age, :string

  interface :named_entity
end

object :business do
  field :name, :string
  field :employee_count, :integer

  interface :named_entity
end