Perform repository actions as administrator in a transaction

I have faced the need to run a code as admin several times and every time i needed to look for how this was done correctly. Let's put a stick on my wall :-)


you will need:

1. An AuthenticationUtil for handling the Authentication as and access of the method as a given user: runAs.
   
2. A RetryingTransactionHelper to handle transactions requirements
3. optionally I use here the synchronized modificator for the specific need of this example.
   

public synchronized Long getNextContractNumber() { 
            return AuthenticationUtil.runAs(new AuthenticationUtil.RunAsWork<Long>() {  
                public Long doWork() throws Exception {  
                     Long actualValue= null;  
                      RetryingTransactionCallback<Long> transaction = new RetryingTransactionCallback<Long>() {  
                           public Long execute() throws Exception {  
                    
                      List<String> currentNumberPathNames = getPathNames(currentNumberNodePath);          
                      final NodeRef currentNumberNode = getNodeFromPathNames(currentNumberPathNames);  
                      Long currentValue = (Long) nodeService.getProperty(currentNumberNode, PhagModel.PROP_CURRENT_NUMBER);  
                      Long nextValue = currentValue + 1 ;  
                      nodeService.setProperty(currentNumberNode, PhagModel.PROP_CURRENT_NUMBER, nextValue);  
                      return nextValue;  
                    }  
                  };  
                  actualValue = getTransactionHelper().doInTransaction(transaction);    
                  return actualValue;  
                }  
           }, AuthenticationUtil.getAdminUserName());  
      }  

it is a useful tool, it might certainly be useful for many.