Rails 4:如何检查实例是否被删除

Rails 4: how to check if an instance has been deleted

在我们的 Rails 应用程序中,我们有一个 CalendarsController:

class CalendarsController < ApplicationController

  def create
    @calendar = current_user.calendars.create(calendar_params)
    current_user.add_calendar_and_role(@calendar.id, 'Owner')
    if @calendar.save
      current_user.total_calendar_count += 1
      current_user.owned_calendar_count += 1
      current_user.save
      flash[:success] = "Calendar created!"
      redirect_to dashboard_path
    else
      render 'static_pages/home'
    end
  end

  def show
    @calendar = Calendar.find(params[:id])
    @posts = @calendar.posts
    @post = Post.new
  end

  def index
  end

  def edit
  end

  def destroy
    Calendar.find(params[:id]).destroy
    flash[:success] = "Calendar deleted"
    redirect_to dashboard_path
  end

  private

    def calendar_params
      params.require(:calendar).permit(:name)
    end

end

create动作中,当一个新的@calendar被创建时,我们运行@calendar.save检查新实例是否真的被创建,然后执行一些动作。

我们想在我们的 destroy 操作中实施类似的过程。

我们正在考虑更新 destroy 方法,如下所示:

def destroy
  @calendar = Calendar.find(params[:id])
  @calendar.destroy
  if @calendar.delete
    flash[:success] = "Calendar deleted"
    current_user.total_calendar_count -= 1
    if @calendar.administrations.role == "Owner"
      current_user.owned_calendar_count -= 1
    end
  end
  redirect_to dashboard_path
end

此代码的语法是否正确,尤其是 if @calendar.deleteif @calendar.administrations.role == "Owner"

而且,最重要的是,这个 destroy 操作的代码是否有意义?

我相信它会更像:

def destroy
  @calendar = Calendar.find(params[:id])
  calendar_admin_role = @calendar.administrations.role
  if @calendar.destroy
    flash[:success] = "Calendar deleted"
    current_user.total_calendar_count -= 1
    if calendar_admin_role == "Owner"
      current_user.owned_calendar_count -= 1
    end
  end
  redirect_to dashboard_path
end

但经过漫长的一天工作后,这不是我的头等大事,所以可能是错误的。

您是否考虑过使用 persisted? 方法

@calendar.destroy
unless @calendar.persisted?
   ... some code here ....
end