How to close a Duplicate Case Using After Event

Question

Can any one help me out.I shall appreciate your help.

I have trigger written for the Duplicate case to be closed once it is identified as a duplicate with same subject line.But my trigger throws an

ERROR : as Error: Invalid Data. Review all error messages below to correct your data.Apex trigger Case_DuplicateClose caused an unexpected exception, contact your administrator:Case_DuplicateClose: execution of AfterInsert caused by: System.FinalException: Record is read-only: Trigger.Case_DuplicateClose: line 30, column 1.

If i just comment the set id line :it throws an ERROR for my first case itself.I think Somewhere my trigger is wrong

CODE :

trigger Case_DuplicateClose on case (after insert)
{
  Map<String, List<Case>> subjectToCaseList = new Map<String, List<Case>>();

  //set<id> CaseID = new set<id>();

  for(Case c : trigger.new)

  {   //CaseID.add(c.id);

    // System.debug('@@@@@@@@@@@@@@@@@@@@@@@' + );

    if(subjectToCaseList.get(c.Subject) != null)
    {
      subjectToCaseList.get(c.Subject).add(c);
    }
    else
    {
      subjectToCaseList.put(c.Subject, new List<Case> {c});
    }
  }

  // any results from this query are dupes based solely on subject
  for(Case existingCase : [select Id, Subject from Case where Subject in : subjectToCaseList.keySet()])
  {
    for(Case newCase : subjectToCaseList.get(existingCase.Subject))
    { 
      newCase.addError('This case is a duplicate.');

      //newCase.Status = 'Closed';
    }
  }
}

Answer 1

You are running trigger on after insert event. In after trigger record becomes read-only. You should run trigger on "before" if you want to change value in field in current record. After trigger are used to update other objects record which are not part of current trigger context.

trigger Case_DuplicateClose on case (before insert)
{
  Map<String, List<Case>> subjectToCaseList = new Map<String, List<Case>>();

  //set<id> CaseID = new set<id>();

  .......
  .......

 // any results from this query are dupes based solely on subject
  for(Case existingCase : [select Id, Subject from Case where Subject in : subjectToCaseList.keySet()])
  {
    for(Case newCase : subjectToCaseList.get(existingCase.Subject))
    { 
      newCase.addError('This case is a duplicate.');

      newCase.Status = 'Closed';
    }
  }
}

Answer 2

As @Regal said, the records become read-only in the after trigger. i.e. you can not edit any SObject instance that Trigger.new returns.

You can however edit records that you have queried. The code snippet below shows how to do it.

...
List<Case> toUpdate = new List<Case>();
for(Case existingCase : [select Id, Subject from Case where Subject in : subjectToCaseList.keySet() and Status = 'Open']) {
    for(Case newCase : subjectToCaseList.get(existingCase.Subject)) { 
        if (newCase.Id == existingCase.Id) {   
            existingCase.Status = 'Closed';
            toUpdate.add(existingCase);
        }
    }
}
if (toUpdate.size() > 0) {
    update toUpdate;
}

NB: The major downfall of doing this is that update toUpdate; causes the Case triggers to fire again. You won't have an recursion because you are only using an after insert trigger, but you need to be aware that triggers will fire again with this approach.

The query will find all the cases, include the cases that have just been inserted. You would need to add some logic that will be able to detect when there is 2 or more cases with the same subject, otherwise this approach will close all cases that are entered.

---

I don't see any reason why you couldn't implement the same logic in a before trigger. The code below would detect duplicates and close them.

trigger Case_DuplicateClose on Case (before insert) {
    List<String> newSubjects = new List<Subjects>();
    for (Case c : trigger.new) {
        if (c.Status == 'Open') {
            newSubjects.add(c.Subject);
        }
    }

    Set<String> existingSubjects = new Set<Subjects>();
    for (Case c : [select Subject from Case where Subject in :newSubjects and Status = 'Open']) {
        existingSubjects.add(c.Subject);
    }
    for (Case c : trigger.new) {
        if (existingSubjects.contains(c.Subject) != null) {
           c.Status = 'Closed';
        }
    }
}