nil?
As expected, you can use nil? to check if an object is nil. It returns true only when the object is nil. For all other values, it returns false.
nil_object = nil
nil_object.nil? # true
data = Hash.new
data.nil? # falseempty?
You can use this method on strings, arrays, and hashes. It returns true in the following cases:
- String doesn’t have any characters, i.e.
str.length == 0 - Array doesn’t contain any elements, i.e.
arr.length == 0 - Hash doesn’t have any key-value pairs, i.e.
hash.length == 0
[].empty? # true
''.empty? # true
{}.empty? # true
nil.empty? # NoMethodError
false.empty? # NoMethodErrorIt’s important to note that an object can be empty and not nil. For example:
names = []
names.empty? # true
names.nil? # falseIf you try to call .empty? on a nil or any other object, Ruby throws NoMethodError.
nil.empty?
# undefined method `empty?' for nil:NilClass (NoMethodError)blank?
This is a nice syntactic sugar implemented in Rails. An object is blank if it’s nil, false, or empty. For example, nil,false, '', [], {}are all blank.
You can think of blank? as a shorthand for the following code.
!val || val.empty?
Here's how it works for various values.
nil.blank? # true
false.blank? # true
''.blank? # true
[].blank? # true
{}.blank? # trueIn addition, .blank? returns true if a string contains only whitespace characters.
" ".blank? # true
Rails also provides present?, which is the opposite of blank?. It checks if the value is not blank.
That's a wrap. I hope you liked this article and you learned something new.
As always, if you have any questions or feedback, didn't understand something, or found a mistake, please leave a comment below or send me an email. I reply to all emails I get from developers, and I look forward to hearing from you.
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