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

• :name - The name of the interface type. Should be a TitleCased binary. Set automatically.
• :description - A nice description for introspection.
• :fields - A map of Absinthe.Type.Field structs. See Absinthe.Schema.Notation.field/1 and
• :args - A map of Absinthe.Type.Argument structs. See Absinthe.Schema.Notation.arg/2.
• :resolve_type - A function used to determine the implementing type of a resolved object. See also Absinthe.Type.Object’s :is_type_of.

The :resolve_type function will be passed two arguments; the object whose type needs to be identified, and the Absinthe.Execution struct providing the full execution context.

The :__reference__ key is for internal use.