If you could clarify if your question can get a more specific answer that may help you, but for general debugging in Rails I use the amazing Pry Gem. There are also many Pry plugins that you can add to make them more like a traditional debugger where you can step etc
In addition, on rails, you can print things to a log file by calling logger.debug "String of info"in your controllers or using <%= debug @instance_variable_to_debug %>in your views. See the ruby debugging guide for more information.