Scalar Recipes

Scalar Recipes

UUID

@desc """
The UUID scalar type represents a version 4 (random) UUID. Any binary not conforming to this format will be flagged.
"""
defmodule MyApp.Schema.Types.Custom.UUID do
  use Absinthe.Schema.Notation

  alias Ecto.UUID

  scalar :uuid, name: "UUID" do
    serialize &UUID.cast!/1
    parse &cast_uuid/1
  end

  defp cast_uuid(%Absinthe.Blueprint.Input.String{value: value}) do
    UUID.cast(value)
  end

  defp cast_uuid(%Absinthe.Blueprint.Input.Null{}) do
    {:ok, nil}
  end

  defp cast_uuid(_) do
    :error
  end
end

JSON (using Jason)

defmodule MyApp.Schema.Types.Custom.JSON do
  @moduledoc """
  The Json scalar type to allow arbitrary JSON values to be passed in or out.
  """
  use Absinthe.Schema.Notation

  scalar :json, name: "Json" do
    description("""
    The `Json` scalar type represents arbitrary json string data, represented as UTF-8
    character sequences. The Json type is most often used to represent a free-form
    human-readable json string.
    """)

    serialize(&encode/1)
    parse(&decode/1)
  end

  @spec decode(Absinthe.Blueprint.Input.String.t()) :: {:ok, term()} | :error
  @spec decode(Absinthe.Blueprint.Input.Null.t()) :: {:ok, nil}
  defp decode(%Absinthe.Blueprint.Input.String{value: value}) do
    case Jason.decode(value) do
      {:ok, result} -> {:ok, result}
      _ -> :error
    end
  end

  defp decode(%Absinthe.Blueprint.Input.Null{}) do
    {:ok, nil}
  end

  defp decode(_) do
    :error
  end

  defp encode(value), do: value
end