除了在一个字段之外，我如何不允许更新?-HowcanIdisallowupdatesexceptforononefield?

10  

First, you should be using a before_update callback for that sort of thing rather than overriding update. Second, you can store the updatable attributes on the model, and then update them with the plugin. I just wrote this in the browser, so it could be wrong.

首先，您应该为这类事情使用before_update回调，而不是覆盖更新。其次，可以在模型上存储可更新的属性，然后使用插件更新它们。我只是在浏览器里写的，所以可能是错的。

  attr_accessor :updatable_attributes
  before_update :prevent_update

  private
  def prevent_update
    return true if self.changed == self.updatable_attributes
    self.errors.add_to_base "Cannot update a #{ self.to_s }"
    false
  end
end

4  

Late to the game here, but for people viewing this question, you can use attr_readonly to allow writing to a field on create, but not allowing updates.

这里的游戏比较晚，但是对于查看这个问题的人来说，您可以使用attr_readonly允许在create上对字段进行写入，但不允许更新。

See http://api.rubyonrails.org/classes/ActiveRecord/ReadonlyAttributes/ClassMethods.html

参见http://api.rubyonrails.org/classes/ActiveRecord/ReadonlyAttributes/ClassMethods.html

I think it has been available since Rails 2.0

我认为它从Rails 2.0开始就可以使用了

The tricky part is, if you have any attributes that are attr_accessible you have to list your read only attributes there also (or you get a mass assignment error on create):

棘手的部分是，如果你有任何attr_access属性，你必须在那里列出你的只读属性(或者你在create上有一个大的分配错误):

class Post