更新期间ActiveRecord::ReadOnlyRecord (ActiveRecord::ReadOnlyRecord)：

Question

我想我还是个新手，但我还需要你的帮助。当我和一个habtm协会一起工作时，我遇到了问题。我有一张表格，我可以在表格中输入有关计算机的信息。关联habtm是在机器和操作系统之间。

class Machine < ActiveRecord::Base   
   ....
   has_and_belongs_to_many :operatingsystems, :join_table => "machines_operatingsystems", :readonly => false
   ....
end

class Operatingsystem < ActiveRecord::Base
   ....
   has_and_belongs_to_many :machines, :join_table => "machines_operatingsystems", :readonly => false
   ....
end

我用复选框显示操作系统。

我修改了机器控制器的更新

 def update
   params[:machine][:operatingsystem_ids] ||= []
   @machine = Machine.find(params[:id], :readonly => false)
   respond_to do |format|
   if @machine.update_attributes(params[:machine])
    flash[:notice] = 'Machine was successfully updated.'
    format.html { redirect_to(@machine) }
    format.xml  { head :ok }
   else
    format.html { render :action => "edit" }
    format.xml  { render :xml => @machine.errors, :status => :unprocessable_entity }
   end
 end
end

但是，如果我编辑一台机器而没有更改名称，然后单击更新，我会出现以下错误：

ActiveRecord::ReadOnlyRecord (ActiveRecord::ReadOnlyRecord):
app/controllers/machines_controller.rb:72
app/controllers/machines_controller.rb:71:in `update'
passenger (2.2.15) lib/phusion_passenger/rack/request_handler.rb:92:in `process_request'
passenger (2.2.15) lib/phusion_passenger/abstract_request_handler.rb:207:in `main_loop'
passenger (2.2.15) lib/phusion_passenger/railz/application_spawner.rb:441:in `start_request_handler'
passenger (2.2.15) lib/phusion_passenger/railz/application_spawner.rb:381:in `handle_spawn_application'
passenger (2.2.15) lib/phusion_passenger/utils.rb:252:in `safe_fork'
passenger (2.2.15) lib/phusion_passenger/railz/application_spawner.rb:377:in `handle_spawn_application'
passenger (2.2.15) lib/phusion_passenger/abstract_server.rb:352:in `__send__'
passenger (2.2.15) lib/phusion_passenger/abstract_server.rb:352:in `main_loop'
passenger (2.2.15) lib/phusion_passenger/abstract_server.rb:196:in `start_synchronously'
passenger (2.2.15) lib/phusion_passenger/abstract_server.rb:163:in `start'
passenger (2.2.15) lib/phusion_passenger/railz/application_spawner.rb:222:in `start'
passenger (2.2.15) lib/phusion_passenger/spawn_manager.rb:253:in `spawn_rails_application'
passenger (2.2.15) lib/phusion_passenger/abstract_server_collection.rb:126:in `lookup_or_add'
passenger (2.2.15) lib/phusion_passenger/spawn_manager.rb:247:in `spawn_rails_application'
passenger (2.2.15) lib/phusion_passenger/abstract_server_collection.rb:80:in `synchronize'
passenger (2.2.15) lib/phusion_passenger/abstract_server_collection.rb:79:in `synchronize'
passenger (2.2.15) lib/phusion_passenger/spawn_manager.rb:246:in `spawn_rails_application'
passenger (2.2.15) lib/phusion_passenger/spawn_manager.rb:145:in `spawn_application'
passenger (2.2.15) lib/phusion_passenger/spawn_manager.rb:278:in `handle_spawn_application'
passenger (2.2.15) lib/phusion_passenger/abstract_server.rb:352:in `__send__'
passenger (2.2.15) lib/phusion_passenger/abstract_server.rb:352:in `main_loop'
passenger (2.2.15) lib/phusion_passenger/abstract_server.rb:196:in `start_synchronously'

提前感谢您的帮助。

Answer 1

除了machine_id和operatingsystem_id之外，您的machines_operatingsystems表中是否还有其他列？如果是这样，ActiveRecord会将关联返回的记录标记为只读。

一个可能的罪魁祸首是连接表上的时间戳列。如果创建machines_operatingsystems的迁移包含对timestamps的调用，这可能是问题的根源。