使用可枚举#select创建特定数组

Posted 2021-02-27

Useful for when you need to do a find and map specific results to an array for use later

#Instead of using:
books  = Book.find(:all, :order => 'id desc', :limit => 20)
comics = []
books.each do |book|
  comics << book if book.item_type == 'Comic'
end
 
#OR
comics  = Book.find(:all, :order => 'id desc', :limit => 20).map {|book| [book] unless book.item_type == 'Comic'}.flatten!
 
#Use this:
books  = Book.find(:all, :order => 'id desc', :limit => 20)
comics = books.select { |i| i.item_type == 'Comic' }