Is there a more efficient way to update the order of a collection of objects in Rails 3?
Suppose I have a collection of Pages that are ordered by a column called :sibling_order. Is there a more efficient way to update the ordering of the collection than what I'm doing below:
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
Try this:
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
精彩评论