Using with_scope

peryt

This lessen is a little high class, not so basic:
There is a helper method of with_scope:
class Task   belongs_to :project      def self.find_incomplete      find_all_by_complete(false, :order => 'created_at DESC')    end  end  
class TasksController   def index      @tasks = Task.find_incomplete    end  
in the above example, you can call find_incomplete, but if you just want the first 20 records returned by that query, what should you do?
we have to make the find_incomplete method received a hash as a condition like:
@tasks = Task.find_incomplete :limit => 20
then in the definition of the model:
def self.find_incomplete(options = {})
    with_scope :find => options do
       find_all_by_complete(fasle, :order => 'create_at DESC')
    end
end
Any find executed within the with_scope block will automatically inherit the specified options, This will also work within another scope
(注意，在这里，更好的办法是使用find_scope 而不是 with_scope, 但是具体如何使用我还是不清楚，呵呵，不好意思。)
这样，就可以像如下这样使用了：
@tasks = @project.tasks.find_incomplete :limit => 20  
               
               
               

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