CODEWITHSUNDEEP
ruby-on-railsrubyactiverecord
Monti
Monti

Reputation: 653

Rails object returns false on present? but true on !nil?

I have a database object in active record. If I call object.find(1).present? it returns false, but it exists. Calling !object.find(1).nil? returns true.

Why is this? I thought !nil == present?.

Upvotes: 1

Views: 4362

Answers (2)

Anthony Michael Cook
Anthony Michael Cook

Reputation: 1085

To better answer your question lets look at the implementation:

def present?
  !blank?
end

We don't see nil? mentioned here, just blank?, so lets check out blank? as well:

def blank?
  respond_to?(:empty?) ? !!empty? : !self
end

So essentially, if the object responds_to empty? it will call out to that for the result. Objects which have an empty? method include Array, Hash, String, and Set.

Further Reading

Upvotes: 5

user229044
user229044

Reputation: 239230

nil? and present? are not opposites.

Many things are both not present? and not nil?, such as an empty string or empty array.

"".present? # => false
"".nil? # => false

[].present? # => false
[].nil? # => false

Upvotes: 5

Related Questions