Using with_scope 使用with_scope

class Task < ActiveRecord::Base
  belongs_to :project

  def self.find_incomplete
    find_all_by_complete(false, :order => ‘created_at DESC‘)
  end
end
--------------------------------------------------------

class TasksController < ApplicationController
  def index
    @tasks = Task.find_incomplete
  end
这两段代码的作用是调用find_incomplete方法，返回项目中未完成的任务并按照创建时间降序


这个方法很好但有个局限，就是我们不能限制返回的数据，我们可以用with_scope.修改代码如下：

class Task < ActiveRecord::Base
  belongs_to :project

  def self.find_incomplete(options = {})
    with_scope :find => options do
      find_all_by_complete(false, :order => ‘created_at DESC‘)
    end
  end
end

--------------------------------------------------------

@tasks = @project.tasks.find_incomplete :limit => 20
这样就成功实现了所有未完成任务的前20个

Using with_scope 使用with_scope

原文：http://www.cnblogs.com/JackyKun/p/4870587.html