Is There a Better Way of Checking Nil or Length == 0 of a String in Ruby?
RubyRuby Problem Overview
Is there a better way than the following to check to see if a string is nil OR has a length of 0 in Ruby?
if !my_string || my_string.length == 0
return true
else
return false
end
In C# there's the handy
string.IsNullOrEmpty(myString)
Anything similar to that in Ruby?
Ruby Solutions
Solution 1 - Ruby
When I'm not worried about performance, I'll often use this:
if my_string.to_s == ''
# It's nil or empty
end
There are various variations, of course...
if my_string.to_s.strip.length == 0
# It's nil, empty, or just whitespace
end
Solution 2 - Ruby
If you are willing to require ActiveSupport you can just use the #blank?
method, which is defined for both NilClass and String.
Solution 3 - Ruby
I like to do this as follows (in a non Rails/ActiveSupport environment):
variable.to_s.empty?
this works because:
nil.to_s == ""
"".to_s == ""
Solution 4 - Ruby
An alternative to jcoby's proposal would be:
class NilClass
def nil_or_empty?
true
end
end
class String
def nil_or_empty?
empty?
end
end
Solution 5 - Ruby
As it was said here before Rails (ActiveSupport) have a handy blank? method and it is implemented like this:
class Object
def blank?
respond_to?(:empty?) ? empty? : !self
end
end
Pretty easy to add to any ruby-based project.
The beauty of this solution is that it works auto-magicaly not only for Strings but also for Arrays and other types.
Solution 6 - Ruby
variable.blank? will do it. It returns true if the string is empty or if the string is nil.
Solution 7 - Ruby
nil?
can be omitted in boolean contexts. Generally, you can use this to replicate the C# code:
return my_string.nil? || my_string.empty?
Solution 8 - Ruby
First of all, beware of that method:
As Jesse Ezel says:
> > "The method might seem convenient, but most of the time I have found that this situation arises from trying to cover up deeper bugs.
> Your code should stick to a particular protocol on the use of strings, and you should understand the use of the protocol in library code and in the code you are working with.
> The NullOrEmpty protocol is typically a quick fix (so the real problem is still somewhere else, and you got two protocols in use) or it is a lack of expertise in a particular protocol when implementing new code (and again, you should really know what your return values are)."
And if you patch String class... be sure NilClass has not been patch either!
class NilClass
def empty?; true; end
end
Solution 9 - Ruby
Every class has a nil?
method:
if a_variable.nil?
# the variable has a nil value
end
And strings have the empty?
method:
if a_string.empty?
# the string is empty
}
Remember that a string does not equal nil
when it is empty, so use the empty?
method to check if a string is empty.
Solution 10 - Ruby
Another option is to convert nil to an empty result on the fly:
(my_string||'').empty?
Solution 11 - Ruby
Konrad Rudolph has the right answer.
If it really bugs you, monkey patch the String class or add it to a class/module of your choice. It's really not a good practice to monkey patch core objects unless you have a really compelling reason though.
class String
def self.nilorempty?(string)
string.nil? || string.empty?
end
end
Then you can do String.nilorempty? mystring
Solution 12 - Ruby
Check for Empty Strings in Plain Ruby While Avoiding NameError Exceptions
There are some good answers here, but you don't need ActiveSupport or monkey-patching to address the common use case here. For example:
my_string.to_s.empty? if defined? my_string
This will "do the right thing" if my_string is nil or an empty string, but will not raise a NameError exception if my_string is not defined. This is generally preferable to the more contrived:
my_string.to_s.empty? rescue NameError
or its more verbose ilk, because exceptions should really be saved for things you don't expect to happen. In this case, while it might be a common error, an undefined variable isn't really an exceptional circumstance, so it should be handled accordingly.
Your mileage may vary.
Solution 13 - Ruby
If you are using rails, you can use #present?
require 'rails'
nil.present? # ==> false (Works on nil)
''.present? # ==> false (Works on strings)
' '.present? # ==> false (Works on blank strings)
[].present? # ==> false(Works on arrays)
false.present? # ==> false (Works on boolean)
So, conversely to check for nil or zero length use !present?
!(nil.present?) # ==> true
!(''.present?) # ==> true
!(' '.present?) # ==> true
!([].present?) # ==> true
!(false.present?) # ==> true
Solution 14 - Ruby
Have you tried Refinements?
module Nothingness
refine String do
alias_method :nothing?, :empty?
end
refine NilClass do
alias_method :nothing?, :nil?
end
end
using Nothingness
return my_string.nothing?
Solution 15 - Ruby
For code golfers:
if my_string=~/./
p 'non-empty string'
else
p 'nil or empty string'
end
Or if you're not a golfer (requires ruby 2.3 or later):
if my_string&.size&.positive?
# nonzero? also works
p 'non-empty string'
else
p 'nil or empty string'
end
Solution 16 - Ruby
In rails you can try #blank?
.
Warning: it will give you positives when string consists of spaces:
nil.blank? # ==> true
''.blank? # ==> true
' '.blank? # ==> true
'false'.blank? # ==> false
Just wanted to point it out. Maybe it suits your needs
UPD. why am i getting old questions in my feed? Sorry for necroposting.