Grails: NullPointerException while save() - grails

Question

I am new to Grails, I tried to save domain object by calling save() in my *service.groovy as shown below
render " ${user.username}"
render " ${user.email}"
render " ${user.password}"
def savedUser = user.save(flush: true)
if(savedUser!=null) {
return savedUser
} else {
return user
}
The render shows all elements have the values which have been passed from controller.
but an NullPointerexception is thrown in save().
the actual error got is
ERROR errors.GrailsExceptionResolver - NullPointerException occurred when processing request: [POST]
Validation error might have occurred, but I checked all validation error in controller by using command class.
How can avoid the exception here?

Answer 1

That's pretty nonstandard code. Rather than checking for a null return value, it's more common (and sensible/useful) to check if there were validation errors. E.g.
user.save(flush: true)
if (user.hasErrors()) {
// do something with the invalid "user" instance
}
else {
// do something with the valid "user" instance
}
For your scenario, you can ignore the return value and just work with the original instance:
user.save(flush: true)
return user
If you're working with the standard templates (or something similar) then this should work fine since there's logic there to check if there are attached errors and display them.