use trigger to match and populate field based off of another object

Question

So as the title states I am trying to populate a field from the premium object with data from fetchRates. I have code that works but it is not populating for some reason. Any assistance would be much appreciated.

I am wondering id the premium rate is actually gathering data

Trigger

trigger fetchAgeFactor on priceByAge__c (before insert, before update) 
{
   priceByAge__c[] age = Trigger.new;
   fetchRates.ageRate(age);     
}

Class

 public class fetchRates {
    //integer baseRate = 211.15;
    public static void ageRate(priceByAge__c[] age)
    {
        string ageRate = NULL;
        Premium_Rate__c[] rate;

        for (priceByAge__c a :age){
            ageRate = a.Name;
            for (Premium_Rate__c main :rate){

                if (main.Age_del__c.contains(ageRate)){
                    main.ageRate__c = a.Rate_Factor__c;  
                }
            }
        }



    }
}

Answer 1

You are never selecting the rates from your DB. Try this code:

PS: I think I understand your use case... you want to update priceByAge__c. If you want to update Premium_Rate__c, then let me know and I can change your code.

UPDATE

Changed code per OP's request

Trigger

trigger fetchAgeFactor on priceByAge__c (before insert, before update) 
{
   fetchRates.ageRate(Trigger.new);     
}

Class

 public class fetchRates {
    //integer baseRate = 211.15;
    public static void ageRate(priceByAge__c[] age)
    {
        string ageRate = NULL;
        Set<String> ratesToQuery = new Set<String>();
        for (priceByAge__c a : age){
          ratesToQuery.add(a.Name);
        }

        Premium_Rate__c[] rates = [select Id, Age_del__c, ageRate__c from Premium_Rate__c where in Age_del__c in :ratesToQuery];

       //Set them in a Map
       Map<String, Premium_Rate__c> ratesByName = new Map<String, Premium_Rate__c>();
       for (Premium_Rate__c rate : rates) {
           ratesByName.put(rate.Age_del__c, rate);
       }

        for (priceByAge__c a : age){
            ageRate = a.Name;

            if (ratesByName.containsKey(ageRate))) {

              ratesByName.get(ageRate).Rate_Factor__c = a.ageRate__c;  
            }
        }

       update ratesByName.values();

    }
}