RestQL - create function in PostController with GraphQL

post_controller.ex

defmodule Restql.Web.PostController do
  # ...
  def create(conn, %{"post" => post_params}) do
    graphql conn, """
      mutation CreatePost($title: String!, $body: String!) {
        post(title: $title, body: $body) {
          id
        }
      }
    """, post_params
  end
  # ...
end