ExOperation article: DSL extension

dsl_extension.ex

def authorize(operation, txn_key, action, opts \\ []) do
  user = opts[:user] || operation.context.user

  ExOperation.Operation.step(operation, {:authorize, txn_key}, fn
    %{^txn_key => struct} ->
      policy = (opts[:policy] || struct.__struct__) |> Module.concat(Policy)

      with :ok <- Bodyguard.authorize(policy, action, user, struct: struct) do
        {:ok, :authorized}
      end

    _ ->
      {:ok, :noop}
  end)
end



operation
|> find(:entity, schema: MyApp.Entity)
|> authorize(:entity, :update)