幾種常見Ruby on Rails內置方法介紹
作者：佚名
Ruby on Rails內置方法有些事經常被我們用到的，比如判斷對象是否為空的blank，排序用到的grop_by()等。我們需要詳細的掌握這些應用技巧。
Ruby on Rails是一個功能強大的WEB開發框架，在這里我們將會學到一些經常用到的Ruby on Rails內置方法，幫助大家熟練掌握其應用技巧。#t#
Ruby on Rails內置方法之對象是否為空blank?
- puts [ ].blank? #=> true
- puts { 1 => 2}.blank? #=> false
- puts " cat ".blank? #=> false
- puts "".blank? #=> true
- puts " ".blank? #自動去除前后空格=> true
- puts nil.blank? #=> true
Ruby on Rails內置方法之排序：group_by()
groups = posts.group_by {|post| post.author_id}
Ruby on Rails內置方法之組句：to_sentence()
- puts [ "ant", "bat", "cat"].
to_sentence #=> "ant, bat, and cat"- puts [ "ant", "bat", "cat"].
to_sentence(:connector =>
"and not forgetting")- #=> "ant, bat, and not forgetting cat"
- puts [ "ant", "bat", "cat"].
to_sentence(:skip_last_comma => true)- #=> "ant, bat and cat"
Ruby on Rails內置方法之分組：in_groups_of()
- [1,2,3,4,5,6,7].in_groups_of(3)
{|slice| p slice}- #=> [1, 2, 3]
- [4, 5, 6]
- [7,nil, nil]
- [1,2,3,4,5,6,7].in_groups
_of(3,"X") {|slice| p slice}- #=> [1, 2, 3]
- [4, 5, 6]
- [7,"X", "X"]
Ruby on Rails內置方法之字符串方法：
- string = "Now is the time"
- puts string.at(2) #=> "w"
- puts string.from(8) #=> "he time"
- puts string.to(8) #=> "Now is th"
- puts string.first #=> "N"
- puts string.first(3) #=> "Now"
- puts string.last #=> "e"
- puts string.last(4) #=> "time"
- puts string.starts_with?("No") #=> true
- puts string.ends_with?("ME") #=> false
- count = Hash.new(0)
- string.each_char {|ch| count[ch] += 1}
- p count #=> {" "=>3, "w"=>1, "m"=>1,
"N"=>1, "o"=>1, "e"=>2, "h"=>1,
"s"=>1, "t"=>2, "i"=>2}
責任編輯：曹凱
來源：
博客園
