Grails GORM web flow iterating through hasMany references
===

I'm still relatively new to Grails. I'm developing an online survey. I keep running into issues with webflow that I can't seem to find solutions for on the web. I have a class Survey that has many Topics that has many questions. In my web flow the amount of topics and questions are dynamic depending on which survey you choose. My question is how can you iterate (in the web flow) through each of the topics and questions (sort of like an arrray or list) where I can grab specific ones and set them to the flow variable. for example I'll give my Survey and Topic class:

    class Survey implements Serializable {
	
	List topic
	String surveyName
	float version
	static hasMany = [topic:Topic]

	static constraints = {

		surveyName (blank:false)
	}
    }

and Topic:

    class Topic implements Serializable {

	List primaryQuestion
	String topicName
	static belongsTo = [survey:Survey]
	static hasMany = [primaryQuestion:PrimaryQuestion]


	static constraints = {

		topicName (blank:false)
	}
    }

So I set my flow variable

    	onStart {
			flow.survey = Survey.get(params.id)
		}

So how can I get each individual topic and question? I can't seem to find this anywhere. I need to go through all the hasMany references and pull those variables to use inside my rendered views. Thanks!!