use-enums-with-graphql.md

Use Enums with GraphQL

If you define an Ash.Type.Enum, that enum type can be used both in attributes and arguments. You will need to add graphql_type/0 to your implementation. AshGraphql will ensure that a single type is defined for it, which will be reused across all occurrences. If an enum type is referenced, but does not have graphql_type/0 defined, it will be treated as a string input.

For example:

defmodule AshPostgres.Test.Types.Status do
  @moduledoc false
  use Ash.Type.Enum, values: [:open, :closed]

  def graphql_type, do: :ticket_status

  # Optionally, remap the names used in GraphQL, for instance if you have a value like `:"10"`
  # that value is not compatible with GraphQL

  def graphql_rename_value(:"10"), do: :ten
  def graphql_rename_value(value), do: value

  # You can also provide descriptions for the enum values, which will be exposed in the GraphQL
  # schema.
  # Remember to have a fallback clause that returns nil if you don't provide descriptions for all
  # values.

  def graphql_describe_enum_value(:open), do: "The post is open"
  def graphql_describe_enum_value(_), do: nil
end

Using custom absinthe types

You can implement a custom enum by first adding the enum type to your absinthe schema (more here). Then you can define a custom Ash type that refers to that absinthe enum type.

# In your absinthe schema:

enum :status do
  value(:open, description: "The post is open")
  value(:closed, description: "The post is closed")
end

# Your custom Ash Type
defmodule AshGraphql.Test.Status do
  use Ash.Type.Enum, values: [:open, :closed]

  use AshGraphql.Type

  @impl true
  # tell Ash not to define the type for that enum
  def graphql_define_type?(_), do: false
end