Rails:. Nil? ,. Empty?,. Blank?. Present? The difference

. Nil? ,. Empty?,. Blank?. Present? The difference

First of all, these three are empty. and. Nil? And. Empty? Is the Ruby method: blank? It's the rails approach.

. Nil? Determines whether an object exists (nil). Non-existent objects are nil.

. Empty? The object already exists, judging whether it is an empty field, such as whether a string is empty, or whether there is a value in an array. A bit like judging whether the length is zero, hehe

. Blank? Equivalent to simultaneously satisfying. Nil? And. Empty? The explanation in Railsapi is if the object is: false, empty, white space character.   For example: "," ", nil, [], and {} are all blank. (Object.blank?) Equivalent to object.nil?| | Object.empty?)

. Present? (the opposite of Rails blank? is present?)

Rails:. Nil? ,. Empty?,. Blank?. Present? The difference