Testing for empty or nil-value string [duplicate]

I'm trying to set a variable conditionally in Ruby. I need to set it if the variable is nil or empty (0 length string). I've come up with the following:

variable = id if variable.nil? || (!variable.nil? && variable.empty?)

While it works, it doesn't seem very Ruby-like to me. Is the a more succinct way of expressing the above?

The second clause does not need a !variable.nil? check—if evaluation reaches that point, variable.nil is guaranteed to be false (because of short-circuiting).

This should be sufficient:

variable = id if variable.nil? || variable.empty?

If you're working with Ruby on Rails, Object.blank? solves this exact problem:

An object is blank if it’s false, empty, or a whitespace string. For example, "", " ", nil, [], and {} are all blank.

If you're in Rails, .blank? should be the method you are looking for:

a = nil
b = []
c = ""

a.blank? #=> true
b.blank? #=> true
c.blank? #=> true

d = "1"
e = ["1"]

d.blank? #=> false
e.blank? #=> false

So the answer would be:

variable = id if variable.blank?