未定义的方法“空”？ 对于nil：NilClass

Question

我在下拉字段中显示一个小时数组

[["09:30am", "2013-02-14 09:30:00"], ["10:00am", "2013-02-14 10:00:00"] ...

我用以下方法渲染数组：

<%= f.select :atime, @time_options %>

我将数组的值分配给控制器中的实例变量

  def new
    @time_options = Appointment.time_options
    @doctor = Doctor.find(params[:doctor_id])
    @appointment = @doctor.schedule.appointments.build

  end

  # GET /appointments/1/edit
  def edit
    @time_options = Appointment.time_options
    @doctor = Doctor.find(params[:doctor_id])
    @appointment = @doctor.appointments.find(params[:id])
  end

  # POST /appointments
  # POST /appointments.json
  def create
    @time_options = Appointment.time_options    
    @doctor = Doctor.find(params[:doctor_id])
    @appointment = @doctor.schedule.appointments.new(params[:appointment])


      if @appointment.save
        #send email
        AppointmentMailer.appointment_confirmation(@appointment, I18n.locale).deliver
        AppointmentMailer.new_appointment(@appointment, I18n.locale).deliver

        redirect_to :action => 'thank_you'
      else
        render action: 'new'
      end
  end

在模型中，我定义了一个类方法来构建数组

  def self.time_options
    start_of_day = Time.zone.now.beginning_of_day
    start_time = start_of_day + 9.hours
    end_time = start_of_day + 17.hours

    lunch_start = start_of_day + 13.hours
    lunch_end = start_of_day + 14.hours + 30.minutes

    times = []
    until start_time > end_time
      start_time = (start_time + 30.minutes)
      unless start_time >= lunch_start && start_time < lunch_end
        times << start_time
      end
    end
    times.map{|t| [t.strftime("%I:%M%p").downcase, t.to_s(:db)] }
  end

但是，当我提交表单时，我得到的undefined method空吗？ 对于nil：NilClass`错误：

<%= f.select :atime, @time_options %>

我做错了什么？

Answer 1

这个

 <%= f.select :atime, @time_options %>

应该是这样的

  <%= f.select :atime_id, @time_options %>

Answer 2

在create方法中，从@doctor开始，然后沿着链条进行：调度，然后是params[:appointment] ，直到找到nil，然后找出为什么它为nil。 如果您正在运行Rails，请使用Rails.logger或撬开它作为您的朋友。