active_model_serializers/docs/howto/add_root_key.md

How to use add root key

Add the root key to your API is quite simple with AMS. The Adapter is what determines the format of your JSON response. The default adapter is the FlattenJSON which doesn't have the root key, so your response is something similar to:

{
  id: 1,
  title: "Awesome Post Tile",
  content: "Post content"
}

In order to add the correspondent root key you need to use the JSON Adapter, you can change this in an initializer:

ActiveModel::Serializer.config.adapter = :json_api

or

ActiveModel::Serializer.config.adapter = ActiveModel::Serializer::Adapter::Json

This will add the root key to all your serialized endpoints.

ex:

{
  post: {
    id: 1,
    title: "Awesome Post Tile",
    content: "Post content"
  }
}

or if it returns a collection:

{
  posts: [
    {
      id: 1,
      title: "Awesome Post Tile",
      content: "Post content"
    },
    {
      id: 2,
      title: "Another Post Tile",
      content: "Another post content"
    }
  ]
}