Question

假设我有一个由名为：sibling_order的列排序的Pages集合。是否有一种更有效的方式来更新集合的顺序，而不是我在下面所做的：

class Page < ActiveRecord::Base

...

def update_order(order)
  if (order < self.sibling_order)
    siblings = Page.where("parent_id = ? AND sibling_order < ? AND sibling_order >= ?",new_parent_id,self.sibling_order,order)
    siblings.collect{|s|s.update_attribute(:sibling_order,s.sibling_order + 1)}      
  elsif (order > self.sibling_order)
    siblings = Page.where("parent_id = ? AND sibling_order > ? AND sibling_order <= ?",new_parent_id,self.sibling_order,order)
    siblings.collect{|s|s.update_attribute(:sibling_order,s.sibling_order - 1)}      
  end    
  self.update_attribute(:sibling_order, order) if self.sibling_order != order             
end

...

end

Answer 1

试试这个：

def update_order(order)
  k = (order < self.sibling_order) ? 1 : -1 
  sql = "parent_id = ? AND " + ( k == 1 ? 
          "sibling_order < ? AND sibling_order >= ?" :
          "sibling_order > ? AND sibling_order <= ?")
  sql = Page.send(:sanitize_sql_array, [sql, new_parent_id, sibling_order,order])
  Page.update_all("sibling_order = sibling_order + (#{k})", sql)
  self.update_attribute(:sibling_order, order) if self.sibling_order != order
end

有没有更有效的方法来更新Rails 3中的对象集合的顺序？

1 个答案: