CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-4
Madhusudhan
Madhusudhan

Reputation: 108

Ruby ternary operator (or) or operator

In Ruby, We often use ternary operator for checking conditions. Similarly we have or operator(||) for using either of the two.

I have scenario where I can use in both ways: Ternary Operator

@question = question.present? ? question : Question.new

Or Operator

@question = question || Question.new

What is the difference between these conditions as both gives the same output? Also which one is better to use in controller method as I am not experienced to decide by my own.

Upvotes: 3

Views: 1739

Answers (3)

Enrai
Enrai

Reputation: 593

The ternary operator checks the condition and if it is true returns the first value, else returns the second value. Using it you can specify the condition, upon which to decide what value to return.

The OR operator works the following way - if the first expression is not nil or false, return it, otherwise return the second expression. Here you are not able to specify the condition, because the check is made directly on the first value you want to return. The OR operator can be represented like:

if question
  @question = question
else
  @question = Question.new
end

Deciding which one to use depends entirely on the condition you want to apply. In your case you want to assure that the question is not nil. So the OR operator is fine in this case and is shorter than the ternary operator. Hope that gives some clarification.

Upvotes: 1

Marek Lipka
Marek Lipka

Reputation: 51191

The difference here is that, for example, [].present? or ''.present? both return false. So:

question = ''
@question = question.present? ? question : Question.new
# => result of Question.new
@question = question || Question.new
# => ''

But it shouldn't mean anything in your case if question can only hold nil or Question instance (which is always present, assuming it's a regular ActiveRecord model). So it's more a matter of personal taste.

Upvotes: 8

shivam
shivam

Reputation: 16506

For this case you can use any one of them, both are same.

I would prefer using @question = question || Question.new as its easier to read.

However there are many cases where both || and ternary operators have different outputs. So you cannot take this for granted.

Upvotes: 0

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