A concise explanation of nil v. empty v. blank in Ruby on Rails

Try this simple solution,

The keyword .nil? used any object  is true or  nil.  And .empty?   string it returns true.

• String length == 0
• Array length == 0
• Hash length == 0

 when Running .empty? It will throw a NoMethodError. The .blank? comes in  implemented by Rails on any object  work like .empty? on string.

nil.blank? == true
false.blank? == true
[].blank? == true
{}.blank? == true
"".blank? == true
5.blank? == false
0.blank? == false

The .blank?  evaluates true on string.  And Rails also provides .present? .The returns  negation .blank?.

"  ".blank? == true
"  ".empty? == false

Array gotcha: blank? will return false  if all elements  an array are blank in this case, use all? with blank?,

Example:

[ nil, '' ].blank? == false
[ nil, '' ].all? &:blank? == true

Here is the simple code:  

 Any Expressions:  !obj.blank? == obj.present?

Explanation:

    Difference  .nil? and .empty? the methods are provided in  Ruby,  As .blank? is added in web development framework Rails.