Check if not nil and not empty in Rails shortcut

Question

I have a show page for my Users and each attribute should only be visible on that page  if it is not nil and not an empty string  Below I have my controller and it is quite annoying having to write the same line of code  user city    nil  amp  amp   user city       for every variable  I am not too familiar with creating my own methods  but can I somehow create a shortcut to do something like this   city   check attr  user city   Or is there a better way to shorten this procedure   users controller rb  def show     city    user city    nil  amp  amp   user city          state    user state    nil  amp  amp   user state          bio    user bio    nil  amp  amp   user bio          contact    user contact    nil  amp  amp   user contact          twitter    user twitter    nil  amp  amp   user twitter          mail    user mail    nil  amp  amp   user mail       end

User · Answer

You can use  present  which comes included with ActiveSupport    city    user city present    etc         You could even write it like this  def show    w city state bio contact twitter mail  each do  attr      instance variable set     attr     user attr  present    end end     It s worth noting that if you want to test if something is blank  you can use  blank   this is the opposite of  present    Also  don t use foo    nil  Use foo nil  instead

User · Answer

There s a method that does this for you   def show    city    user city present  end   The present  method tests for not-nil plus has content  Empty strings  strings consisting of spaces or tabs  are considered not present   Since this pattern is so common there s even a shortcut in ActiveRecord   def show    city    user city  end   This is roughly equivalent   As a note  testing vs nil is almost always redundant  There are only two logically false values in Ruby  nil and false  Unless it s possible for a variable to be literal false  this would be sufficient   if  variable          end   This is preferable to the usual if   variable nil   or if  variable    nil  stuff that shows up occasionally  Ruby tends to wards a more reductionist type of expression   One reason you d want to compare vs  nil is if you have a tri-state variable that can be true  false or nil and you need to distinguish between the last two states

[ruby-on-rails] Check if not nil and not empty in Rails shortcut?

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