java - Grails error validating on existing input -

i got error when tried modify controller (generated scaffolding). want do, add current user capture springsecurity service.

payment class has user property inside. tried inject user value springsecurityservice.getcurrentuser();

when tried this, produce error : property [user] of class [class kks.payment] cannot null

i tried debug, looks fine still producing error ....

this work if put user.id inside form hidden value .. didn't want ...

how solve problem ?

here code:

class paymentcontroller {      def springsecurityservice;      @transactional     def save(payment paymentinstance) {         println("1..... payment");         paymentinstance.user = springsecurityservice.getcurrentuser();         if (paymentinstance == null) {             notfound()             return         }          println("2..... payment"+springsecurityservice.getcurrentuser().class);         println(paymentinstance.user.id); // still okay !!!           if (paymentinstance.haserrors()) {             println("3..... haserrors?"); // entered here  property [user] of class > [class kks.payment] cannot null              respond paymentinstance.errors, view: 'create'             return         }           println("3..... payment");         paymentinstance.save flush: true          request.withformat {             form multipartform {                 flash.message = message(code: 'default.created.message', args: >[message(code: 'payment.label',                                         default: 'payment'), paymentinstance.id])                 redirect paymentinstance             }             '*' { respond paymentinstance, [status: created] }         }     }  } 

after inserting value in paymentinstance should validate instance like:

paymentinstance.user = springsecurityservice.getcurrentuser(); paymentinstance.validate() 

and check error.

ps: please follow convention: variable name should started lower case character.