ruby中nil?, empty? and blank?
2014-09-04 09:11
274 查看
In Ruby, you check with
Rails adds the method
An object is blank if it‘s false, empty, or a whitespace string. For example, "", " ", nil, [], and {} are blank.
This simplifies
to
String length == 0
Array length == 0
Hash length == 0
nil?if an object is nil:
article = nil article.nil? # => true
empty?checks if an element - like a string or an array f.e. - is empty:
# Array [].empty? #=> true # String "".empty? #=> true
Rails adds the method
blank?to the
Objectclass:
An object is blank if it‘s false, empty, or a whitespace string. For example, "", " ", nil, [], and {} are blank.
This simplifies
if !address.nil? && !address.empty?
to
if !address.blank? .nil? - It is Ruby method - It can be used on any object and is true if the object is nil. - "Only the object nil responds true to nil?" - RailsAPI nil.nil? = true anthing_else.nil? = false a = nil a.nil? = true “”.nil = false .empty? - It is Ruby method - can be used on strings, arrays and hashes and returns true if:
String length == 0
Array length == 0
Hash length == 0
- Running .empty? on something that is nil will throw a NoMethodError "".empty = true " ".empty? = false .blank? - It is Rails method - operate on any object as well as work like .empty? on strings, arrays and hashes. nil.blank? = true [].blank? = true {}.blank? = true "".blank? = true 5.blank? == false - It also evaluates true on strings which are non-empty but contain only whitespace: " ".blank? == true" ".empty? == false Quick tip: !obj.blank? == obj.present? activesupport/lib/active_support/core_ext/object/blank.rb, line 17 # (Ruby 1.9) def present? !blank? end
相关文章推荐
- ruby中nil?, empty? and blank?的选择
- 【转】ruby中nil?, empty? and blank?的选择
- ruby : nil?, empty? and blank?的选择
- 理解RoR(Ruby on Rails)中 nil? empty? blank?方法的区别
- .nil? .empty? .blank? .present? in Ruby on Rails
- Ruby中的nil?,empty?与Rails中的blank?,present?
- .nil? .empty? .blank? .present? in Ruby on Rails
- Ruby的.nil? .empty? .blank? .present?差别
- ruby -- 基础学习(五)empty、nil、blank三者之间的区别
- how to remove nil and blank string in an array in Ruby
- nil? blank? empty? 的区别
- Rails :.nil? , .empty?, .blank? .present? 的区别
- Rails -- empty、nil、blank三者之间的区别
- Ruby的.nil? .empty? .blank? .present?区别
- Rails中nil? empty? blank? present?的区别
- RAILS关于 NIL? PRESENT? EMPTY? ANY? BLANK?
- Ruby学习笔记-Block, Proc and Lambda
- [笔记]C++ Empty Class(analysis construcor and desturctor)
- [StringUtil ] isEmpty VS isBlank
- install OpenSSL and rebuild ruby (preferred) or use non-HTTPS sources 和uninitialized constant Gem: