有多种方法可以做到这一点:

如果希望以这种方式对该关联的所有调用进行排序,则可以在创建关联时指定排序,如下所示:

class Log < ActiveRecord::Base
  has_many :items, :order => "some_col DESC"
end

您也可以使用一个命名的_scope来执行此操作,它允许在访问任何时间项时轻松指定排序:

class Item < ActiveRecord::Base
  named_scope :ordered, :order => "some_col DESC"
end

class Log < ActiveRecord::Base
  has_many :items
end

log.items # uses the default ordering
log.items.ordered # uses the "some_col DESC" ordering

如果您总是希望在默认情况下以相同的方式订购项目,则可以使用(rails 2.3中的new)默认_scope方法,如下所示:

class Item < ActiveRecord::Base
  default_scope :order => "some_col DESC"
end

Rails 4.2.20 语法要求用块调用:

class Item < ActiveRecord::Base
  default_scope { order('some_col DESC') }
end

这也可以用另一种语法编写:

default_scope { order(some_col: :desc) }

这两种方法都可以:

Item.all(:conditions => {:log_id => some_log.id}, :order => "some_col DESC")
some_log.items.all(:order => "some_col DESC")

设置 default_scope 在你的模型课上

class Item < ActiveRecord::Base
  default_scope :order => "some_col DESC"
end

这会起作用