Ruby on Rails：在数组中的元素之间插入逗号的简短手段？

Question

users_allowed_to_be_viewed.map {|u| "#{u.id},"}

but that gives 1,2,3,

What would be a short way to just get something like 1,2,3

Answer 1

an array?

from http://ruby-doc.org/core/classes/Array.html

 array.join(sep=$,) → str

Returns a string created by converting each element of the array to a string, separated by sep.

       [ "a", "b", "c" ].join        #=> "abc"
       [ "a", "b", "c" ].join("-")   #=> "a-b-c"

Answer 2

users_allowed_to_be_viewed.map{|u| u.id}.join(",")

Answer 3

users_allowed_to_be_viewed.map(&:id).join(',')

Array#join也是Array#*别名，虽然这可能会让事情变得有点迟钝：

users_allowed_to_be_viewed.map(&:id) * ','

Answer 4

users_allowed_to_be_viewed.join ',' 

ruby-1.8.7-p299 > users_allowed_to_be_viewed = [1,2,3]
   => [1, 2, 3] 
ruby-1.8.7-p299 > users_allowed_to_be_viewed.join ',' 
    => "1,2,3"