如何在视图中添加另一个应该是只读的列，并且只能通过代码中的 SQL 查询显式更改

Question

我的 Ruby on Rails 4.1.4 应用程序中有一个表，我想添加另一个列，该列在视图中应该是只读的，并且只能通过代码中的 SQL 查询显式更改。

我怎样才能实现这样的行为？

提前致谢。

Answer 1

假设您使用的是强参数，您可以从控制器的强参数列表中删除该列。

以下是来自strong_parameters github repo 的一些示例代码，用于了解您是否使用了强参数：

class PeopleController < ActionController::Base
  # This will raise an ActiveModel::ForbiddenAttributes exception because it's using mass assignment
  # without an explicit permit step.
  def create
    Person.create(params[:person])
  end

  # This will pass with flying colors as long as there's a person key in the parameters, otherwise
  # it'll raise an ActionController::MissingParameter exception, which will get caught by
  # ActionController::Base and turned into that 400 Bad Request reply.
  def update
    person = current_account.people.find(params[:id])
    person.update_attributes!(person_params)
    redirect_to person
  end

  private
    # Using a private method to encapsulate the permissible parameters is just a good pattern
    # since you'll be able to reuse the same permit list between create and update. Also, you
    # can specialize this method with per-user checking of permissible attributes.
    def person_params
      params.require(:person).permit(:name, :age)
    end
end

person_params 中的内容就是 strong_parameters 的作用。