CODEWITHSUNDEEP
ruby
B Seven
B Seven

Reputation: 45943

Is there a Ruby string#blank? method?

String#blank? is very useful, but exists in Rails, not Ruby.

Is there something like it in Ruby, to replace:

str.nil? || str.empty?

Upvotes: 12

Views: 9660

Answers (6)

Tushar H
Tushar H

Reputation: 805

Anyone new looking for this, can use simple_ext gem. This gem helps you to use all the Ruby core extensions on objects like Array, String, Hash etc. from rails.

require 'simple_ext'
str.blank?
arr.blank?
... etc.

Upvotes: 1

aromero
aromero

Reputation: 25761

AFAIK there isn't anything like this in plain Ruby. You can create your own like this:

class NilClass
  def blank?
    true
  end
end

class String
  def blank?
    self.strip.empty?
  end
end

This will work for nil.blank? and a_string.blank? you can extend this (like rails does) for true/false and general objects:

class FalseClass
  def blank?
    true
  end
end

class TrueClass
  def blank?
    false
  end
end

class Object
  def blank?
    respond_to?(:empty?) ? empty? : !self
  end
end

References:

https://github.com/rails/rails/blob/2a371368c91789a4d689d6a84eb20b238c37678a/activesupport/lib/active_support/core_ext/object/blank.rb#L57 https://github.com/rails/rails/blob/2a371368c91789a4d689d6a84eb20b238c37678a/activesupport/lib/active_support/core_ext/object/blank.rb#L67 https://github.com/rails/rails/blob/2a371368c91789a4d689d6a84eb20b238c37678a/activesupport/lib/active_support/core_ext/object/blank.rb#L14 https://github.com/rails/rails/blob/2a371368c91789a4d689d6a84eb20b238c37678a/activesupport/lib/active_support/core_ext/object/blank.rb#L47

And here is the String.blank? implementation which should be more efficient than the previous one:

https://github.com/rails/rails/blob/2a371368c91789a4d689d6a84eb20b238c37678a/activesupport/lib/active_support/core_ext/object/blank.rb#L101

Upvotes: 17

Marc-André Lafortune
Marc-André Lafortune

Reputation: 79562

No such function exist in Ruby, but there is an active proposal for String#blank? on ruby-core.

In the meantime, you can use this implementation:

class String
  def blank?
    !include?(/[^[:space:]]/)
  end
end

This implementation will be very efficient, even for very long strings.

Upvotes: 2

Mark Thomas
Mark Thomas

Reputation: 37517

You can always do exactly what Rails does. If you look at the source to blank, you see it adds the following method to Object:

# File activesupport/lib/active_support/core_ext/object/blank.rb, line 14
  def blank?
    respond_to?(:empty?) ? empty? : !self
  end

Upvotes: 4

hd1
hd1

Reputation: 34677

Assuming your string can be stripped, what's wrong with str.nil? or str.strip.empty? as in the following:

2.0.0p0 :004 > ' '.nil? or ' '.strip.empty? 
 => true

Upvotes: 2

christianblais
christianblais

Reputation: 2458

What about something like:

str.to_s.empty?

Upvotes: 3

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