Recursive trigger

Question

This is my trygger on Opportunity object.

trigger AutoProductupdate on Opportunity ( before update,after update) {
  static boolean already=false;
  if (already==false){
    for(Opportunity newOppt : Trigger.new){       
      if  (trigger.isAfter){
        if (newOppt.Pricing_Tears__c.trim()=='Gigabyte'){                                   
          SYSTEM.DEBUG('update');

          Automations.UpdateOpportunityLineItems(newOppt);
          //Action of the called function: 
          //DELETE OPPORTUNITY LINE ITEM SCHEDULES FOR ALL THE PRODUCTS
          // UPDATE OPPORTUNITY LINE ITEM
          Automations.SheduleOpportunityLineItem(newOppt);
          //Action of the called function: 
          // CREATE OPPORTUNITY LINE ITEM SCHEDULES FOR ALL THE PRODUCTS
        }
      }  
    }        

    already=true; 
   }                   
}

I am working with opportunity product and opportunity product schedules. In the debug log i see that the trigger is working recursively (It 's printed 15 times the string 'update' with the system.debug).

The error message:

execution of AfterUpdate caused by: System.DmlException: Delete failed. First exception on row 0 with id 00oL0000000acVqIAI; first error: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, AutoProductupdate: maximum trigger depth exceeded Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ] Opportunity trigger event AfterUpdate for [006L0000003EUVZ]: []: Class.Automations.UpdateOpportunityLineItems: line 70, column 1

Which is the problem?

How can avoid this?

Answer 1

It looks like your method Automations.UpdateOpportunityLineItems is causing the loop so I would recommend a couple of fixes:

1. You probably need to set already=true earlier, immediately after the if (already==false) statement. By delaying this assignment to the end you aren't preventing the loop.

2. Do not allow the called methods to execute DML; instead, provide them with a global static map<Id, sObject> variable for each sObject type. These methods would place the updated records in the global object, which would then be updated at the end.

Answer 2

Solution: Use a static variable

in an Apex class

(you mustn't set the static variable in the trigger, create a class) to avoid an infinite loop.

http://www.salesforce.com/docs/developer/cookbook/Content/apex_controlling_recursive_triggers.htm

Answer 3

Introducing static variables to control recursion may be a good start, but soon might lead to messy code if you have huge apex codebase to handle your business logic.

There are several design patterns to handle recursive triggers. Check out Dan Appleman's Advanced Apex Programming to see his proposal towards handling recursion. Alternatively, you might want to check my blog post on 'An architecture framework to handle apex triggers in Force.com platform' which solves not only the recursion, but also promotes SOC, clean code structure and control execution order.