View.ex

mymodel_controller.ex

defmodule MyApp.MyModelController do                                                                                                                                                            
  use MyApp.Web, :controller                                                                               
  plug :action                                                                                                
  
  def show(conn, params) do
    render conn, "show.json", data: Repo.get!(MyModel, params[:id])
  end
end

mymodel_view.ex

defmodule MyApp.MyModelView do                                                                                                                                                                  
  use MyApp.Web, :view
  @attributes ~W(id body title user comments inserted_at)
  
  def render("show.json", %{data: data}) do
    data
    |> Map.take(@attributes)
    |> Map.update!(:title, &String.capitalize)
  end
end