在其中添加额外代码后，删除操作无效

Question

我在我的控制器中删除了动作，这是pickups_controller.rb中的代码

  def delete
    @pickup = Pickup.find(params[:id])
    if [email protected]?
      @pickup.destroy
      render json: { success_message: "Success!, Pickup is deleted." }, status: :ok
    end
  end

我使用assets / javascripts / pickups.js按下按钮，使用javascript json调用delete操作

document.addEventListener("DOMContentLoaded", function(event) {



    var xhttp = new XMLHttpRequest();

    // delete the pickup you choose

    $('.removepickup.btn.btn-primary').on('click', function() {
        var pickup_div = $(this).parents('.removepickupparent');
        var pickup_id = pickup_div.attr('id');
        var x = "../deletepickup?id=" + pickup_id;
        $.ajax({
            type: "POST",
            url: x,
            success: function(data) {
                var success = data.success_message;
                $(".successr"+ pickup_id).text(success).show(0).delay(1000).hide(0);   
                setTimeout(function () {
                    location.reload();
                }, 1000);
            },

            error: function (xhr, ajaxOptions, thrownError){
                if(xhr.status==404) {
                    $(".errorl"+ pickup_id).text("Fail!, pickup Is Already Deleted Before").show(0).delay(1000).hide(0);
                    setTimeout(function () {
                         location.reload();
                    }, 2000);
                }
            }

        });
    });



    // when pressing on this button, it redirects you to create pickup page

    $('.addpickup.btn.btn-primary').on('click', function() {
        var success = "Redirecting to add pickup Page"
        $(".successp").text(success).show(0).delay(2000).hide(0);
        setTimeout(function () {
        $(location).attr('href', '../createpickup');
        }, 2000);

    });


});

该函数运行良好，但在删除操作中添加4行额外代码时，它不起作用，这是在我的删除操作中添加4行额外代码后的代码，并且操作无效。

  def delete
    @pickup = Pickup.find(params[:id])
    if [email protected]?

      # the start of the extra code
      @trip = Trip.find(@pickup.trip_id)
      if [email protected]?
        @trip.seatsno = @trip.seatsno + 1
        @trip.save
      end
      # the end of the extra code

      @pickup.destroy
      render json: { success_message: "Success!, Pickup is deleted." }, status: :ok
    end
  end 

有什么解决方案吗..知道我还是Ruby on Rails的初学者

注意：

我使用了byebug，当到达etra代码的第一行时，我在本地服务器终端中遇到了这个错误"request.env["action_dispatch.show_detailed_exceptions"] ||= show_detailed_exceptions?"

Answer 1

使用find_by而不是find方法。 find' method raises the exception if a particular record is not found, whilefind_by`返回nil。

用法：

find_by(id: params[:id])

Answer 2

这个答案更多的是重构建议而不是实际答案，但它也可以解决您的问题。

您可以将此操作重构为：

def delete
  @pickup = Pickup.find(params[:id])
  # no need to test @pickup.nil? here because `find` method raise 
  # an ActiveRecord::RecordNotFound error if the record is not found
  # which should be caught by ApplicationController to render a 404
  if @pickup.destroy
    @pickup.trip.update_attributes(seatsno: @pickup.trip.seatsno + 1)
    render json: { success_message: "Success!, Pickup is deleted." }, status: :ok
  else
    render json: { error_message: "Error, Pickup could not be deleted." }, status: 409
  end
end

---

更好的是，将增加seatsno的关注转移到Pickup模型：

# app/models/pickup.rb
after_destroy :increment_trip_seatsno

def increment_trip_seatsno
  self.trip.update_attributes(seatsno: self.trip.seatsno + 1)
end

并从控制器中删除问题。这样，每次通过Rails（控制台或应用程序中的其他位置）销毁Pickup记录时，行程将相应更新。