Sometimes we have faced business requirement to Lock or Unlock records in Salesforce. We can use apex lock() and unlock() methods in the System.Approval namespace to lock and unlock records by passing in record IDs or sObjects.

To enable this feature, go to Setup | Search Automation Settings in the Quick Find box | click on Automation Settings. Then, select Enable record locking and unlocking in Apex.

Lock Record Example:

//Get records to lock
List<case> caseList = [SELECT Id From Case LIMIT 10];
//Lock records
List<Approval.LockResult> lrList = Approval.lock(caseList, false);

// Iterate through each returned result
for(Approval.LockResult lr : lrList) {
    if (lr.isSuccess()) {
        //Operation was successful, so get the ID of the record that was processed
        System.debug('Successfully locked account with ID: ' + lr.getId());
    }
    else {
        //Operation failed, so get all errors                
        for(Database.Error err : lr.getErrors()) {
            System.debug('The following error has occurred.');                    
            System.debug(err.getStatusCode() + ': ' + err.getMessage());
            System.debug('Case fields that affected this error: ' + err.getFields());
        }
    }
}

Unlock Record Example:

//Get records to unlock
List<case> caseList = [SELECT Id From Case LIMIT 10];
//Check locked records
List<case> caseLockList = new List<Case>();
for(Case c :caseList){
    if(Approval.isLocked(c.id)){
        caseLockList.add(c);
    }
}
//Unlock record
if(!caseLockList.isEmpty()){
    //Unlock records
    List<Approval.UnlockResult> ulrList = Approval.unlock(caseLockList, false);
    
    // Iterate through each returned result
    for(Approval.UnlockResult  ulr : ulrList) {
        if (ulr.isSuccess()) {
            //Operation was successful, so get the ID of the record that was processed
            System.debug('Successfully locked account with ID: ' + ulr.getId());
        }
        else {
            //Operation failed, so get all errors                
            for(Database.Error err : ulr.getErrors()) {
                System.debug('The following error has occurred.');                    
                System.debug(err.getStatusCode() + ': ' + err.getMessage());
                System.debug('Case fields that affected this error: ' + err.getFields());
            }
        }
    }
}