How do I check if a column has a value?".

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https://stackoverflow.com/questions/302782/rails-how-do-i-check-if-a-column-has-a-value I am giving a very detailed answer to this Question "How do I check if a column has a value?". First of all, it is important to note that an attribute can have four kinds of values in it. nil value i.e "nil" stored in the database empty value i.e "" an empty string with no spaces empty string with spaces " ". value present in database i.e a non-empty string. Here is the detail behavior of all the present methods(Ruby 2.2.2) that could be used in this case. First Method: .empty? For nil value => Throws an exception 2.2.2 :037 > object.attribute => nil 2.2.2 :025 > object.attribute.empty? NoMethodError: undefined method `empty?' for nil:NilClass For empty value i.e "" an empty string with no spaces 2.2.2 :037 > object.attribute => "" 2.2.2 :025 > object.attribute.empty? true empty string with spaces " ". 2.2.2 :041 > object.attribute => " " 2.2.2 :042 > object.attribute.empty? => false value present in database i.e a non-empty string. 2.2.2 :045 > object.attribute => "some value" 2.2.2 :046 > object.attribute.empty? => false Second Method: .nil? nil value i.e "nil" stored in the database 2.2.2 :049 > object.attribute => nil 2.2.2 :050 > object.attribute.nil? => true empty value i.e "" an empty string with no spaces 2.2.2 :053 > object.attribute => "" 2.2.2 :054 > object.attribute.nil? => false empty string with spaces " ". 2.2.2 :057 > object.attribute => " " 2.2.2 :058 > object.attribute.nil? => false value present in database i.e a non-empty string. 2.2.2 :061 > object.attribute => "some value" 2.2.2 :062 > object.attribute.nil? => false Third Method: .blank? nil value i.e "nil" stored in the database 2.2.2 :065 > object.attribute => nil 2.2.2 :066 > object.attribute.blank? => true empty value i.e "" an empty string with no spaces 2.2.2 :069 > object.attribute => "" 2.2.2 :070 > object.attribute.blank? => true empty string with spaces " ". 2.2.2 :073 > object.attribute => " " 2.2.2 :074 > object.attribute.blank? => true value present in database i.e a non-empty string. 2.2.2 :075 > object.attribute => "some value" 2.2.2 :076 > object.attribute.blank? => false Fourth Method: .present? nil value i.e "nil" stored in the database 2.2.2 :088 > object.attribute => nil 2.2.2 :089 > object.attribute.present? => false empty value i.e "" an empty string with no spaces 2.2.2 :092 > object.attribute => "" 2.2.2 :093 > object.attribute.present? => false empty string with spaces " ". 2.2.2 :096 > object.attribute => " " 2.2.2 :097 > object.attribute.present? => false value present in database i.e a non-empty string. 2.2.2 :100 > object.attribute => "some value" 2.2.2 :101 > object.attribute.present? => true You can use either of the four depending upon the situation you face. Thanks