Simplistic viewer example

schema.ex

defmodule MyApp.Schema do
  use Absinthe.Schema
  
  object :user do
    # Define your user type
  end

  query do
    field :viewer, :user do
      resolve &resolve_viewer/3
    end
  end

  def resolve_viewer(_, _, %{context: %{current_user: user}}) do
    {:ok, user}
  end
  def resolve_viewer(_, _, _) do
    {:ok, nil}
  end  
  
end

See http://absinthe-graphql.org/guides/context-and-authentication/#context-and-plugs to see an example of how to authenticate a user and put the user into the context for Absinthe.