To display an error message when a record is submitted for approval using apex trigger

Question

Please help me with this code, Writing a Trigger to display an error message on Opportunity_Support_Request__c record which has no OSR Product and if it is submitted for Approval(by clicking on Submit for Approval button) it will display the error message(You must add at least one osr Product to your Request).

Opportunity_Support_Request__c is Master object OSR_Product__c is Detail obj OSR_ID__c is the master detail field created on detail object. And the Trigger that I have written is :

trigger OSRapprovalTrigger on Opportunity_Support_Request__c (before insert,before update)
{        
    if(trigger.isUpdate && trigger.isBefore)
    {        
        for(Opportunity_Support_Request__c s : Trigger.new){                        
            if(s.Status__c == 'Not Submitted')
            {
                //Get list of osr products
                List <OSR_Product__c> SampleProductList = [Select CAT_logic_Description__c,Material_Description__c from OSR_Product__c where OSR_ID__c =: s.id ];//
                if(SampleProductList.size() == 0)
                {
                    if(!Test.isRunningTest()){
                        s.addError('You must add at least one osr Product to your Request');
                    }
                }
            }
        }
    }
}

                                                                                            

Please Help. Thanks in advance !

Answer 1

Just to give a sample and one of the ways to implement this:

I created an approval process, just added an action to update any field. In your case it will be your specific field.

After that just wrote a trigger on Opportunity beforeUpdate like this. You can add your conditions.

trigger OpportunityTrigger on Opportunity (before update) {

    if(trigger.isUpdate && trigger.isBefore) {        
        for(Opportunity s : Trigger.new){                        
            s.addError('You must add at least one osr Product to your Request');
        }
    }

}

And when submitting for approval:

got this message:

Now you will have to fix your code for compilation errors and all, but this was just to show that this flow does work and allows us to put a validation in approval process.