exception handling - How to Handle Nil Errors in Rails? -

what correct way deal nil errors in rails? errors like:

nomethoderror (undefined method `questions' nil:nilclass):

for example, let's have chapters in app each have question. call question previous chapter within current question, write following code in question.rb:

def previous_question  self.chapter.previous.question end 

this might cause above-mentioned error, write method in model check if lead nil result:

def has_previous_question?  self.chapter , self.chapter.previous , self.chapter.previous.question end 

if make sure call before calling previous_question, can work, looks ridiculous. there better way deal nil errors in rails?

i not tell right way way of handling kind of situation:

def previous_question   self.chapter.previous.try(:question) end 

that way there won't error, if there no previous chapter, method return nil.

if want return else in case nil, can write:

def previous_question   self.chapter.previous.try(:question) || returning_this_value_instead end 

side note: don't need use self in kind of situation:

def previous_question   chapter.previous.try(:question) || returning_this_value_instead end