Use Blank? To Avoid Code Smells in Rails


To improve my programming skills, I am refactoring some Ruby on Rails projects. I am using code smell tools like reek to do so.

One of the code smells reek checks for is NilCheck. Checking if an object is nil is a type of explicit type checking, indicating abstraction problems. If polymorphism is working then no explicit checks are necessary.

However in rails ActiveRecord objects - unless a default is set in the database - have their fields initialized to nil. But after the object has been saved from a form, strings fields will be empty ("").

How to condition on ‘presence of a string of length more than zero’? We can’t call length since nil.length throws an exception. And if we write string.nil? or string == "", we are making an explicit type check.

However, in rails, both nil and String respond to blank?. Therefore string_variable.blank? will fulfill the role of string_variable.nil? or string_variable == "" nicely, avoiding code smells and unnecessary database defaults.

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