Get all folders in a specific folder

Is there any way to get all folders in a specific folder with API?

I'm using Ruby SDK (Boxr).

I have tried with search method like this.

require 'boxr'

client = Boxr::Client.new("token")
search_query = "\" t* \""
results = client.search(query=search_query, ancestor_folder_ids: ["ID"], type: "folder")
p results.inspect

Actually I need to go with

search_query = "\" * \""

to get all folders, but it didn't work.

I hope it is possible because I get all folders using the search window through UI.

Thank you.