How do I check parameter "param[:some_value]" in Ruby

Question

I know some ways to check if parameter is not nil

if param[:some_value]
if param[:some_value].present?
if !param[:some_value].nil?    #unless param[:some_value].nil? 
if !param[:some_value].blank?  #unless param[:some_value].blank? 

Which one is correct and most popular? What is the difference between them? I'd rather use if param[:some_value] because it is simplest and shorterst.

Answer 1

Here are some differences between nil?, blank? and present?:

>> "".nil?
=> false
>> "".blank?
=> true
>> "".present?
=> false
>> " ".nil?
=> false
>> " ".blank?
=> true
>> " ".present?
=> false

Note that present? translates to not nil and not blank. Also note that while nil? is provided by Ruby, blank? and present? are helpers provided by Rails.

So, which one to choose? It depends on what you want, of course, but when evaluating params[:some_value], you will usually want to check not only that it is not nil, but also if it is an empty string. Both of these are covered by present?.