README

Absinthe one_of

Support an Input Union Type System Directive in Absinthe.

Inspiration

This package was inspired by an article written by Maarten Van Vliet.

You can read the original article Creating an Input Union Type System Directive in Absinthe.

Key Improvements

• Nested Objects: Allows for one_of validation within nested object structures.
• Nested List Objects: Supports one_of validation within nested lists of objects.

Installation

Add :absinthe_one_of to your list of dependencies in mix.exs:

def deps() do
  [
    {:absinthe_one_of, "~> 1.1"}
  ]
end

Usage

Step 1: Define Schema

Create a schema module and define your types, including the @prototype_schema AbsintheOneOf.Directive:

defmodule YourWebApp.Schema do
  use Absinthe.Schema

  @prototype_schema AbsintheOneOf.Directive

  query do
    ...
  end

  mutation do
    ...
  end

  subscription do
    ...
  end

  ...

  input_object(:one_of_input) do
    directive(:one_of)
    field(:a, :a_input)
    field(:b, :b_input)
  end

  input_object(:a_input) do
    ...
  end

  input_object(:b_input) do
    ...
  end
end

Step 2: Setup Absinthe Pipeline

Configure the Absinthe pipeline to include the absinthe_one_of phase:

defmodule YourWebApp.Endpoint do
  use YourWebApp, :router

  ...

  def pipeline(config, pipeline_opts) do
    config.schema_mod
    |> Absinthe.Pipeline.for_document(pipeline_opts)
    |> Absinthe.Pipeline.insert_after(
      Absinthe.Phase.Document.Validation.OnlyOneSubscription,
      AbsintheOneOf.Phase
    )
  end
end

Step 3: Testing

To write tests for your implementation, you can refer to the example tests provided in test/absinthe_one_of_test.exs. These tests demonstrate how to validate the functionality of the one_of directive and ensure that only one field is non-null among several options.

License

This project is licensed under the MIT License - see the LICENSE file for details.