保存foreign_key = nil后-解决db中的错误

Question

我将@booking 与用户（称为“booker”）一起保存。在@booking.save 之后，我可以在命令行中检索@booking.booker，显示用户的所有属性（电子邮件、密码、ID 等）。然而，在离开 create 方法后，无法检索它（例如从节目中）：@booking.booker = nil。 我想这是由于我的预订模型中的一个错误：我有belongs_to 和has_many_through。如果错误来自这里，如何在不更改所有数据库的情况下解决它？

booking_controller.rb

class BookingsController < ApplicationController
  before_action :set_booking, only: [:show, :edit, :update ]
  before_action :set_booking_format, only: [:destroy ]
  def index
  end

  def my_bookings
    @bookings = BookingPolicy::Scope.new(current_user, Booking).scope.where(booker: current_user)
  end

  def show
    authorize @booking
  end

  def new
    @garden = Garden.find(params[:garden_id])
    @booking = Booking.new
    authorize @booking
  end

  def create
    @garden = Garden.find params[:garden_id]
    @booking = @garden.bookings.build(booker: current_user)

    authorize @booking
    if @booking.save
      redirect_to garden_booking_path(@booking, current_user)
    end
  end

  def update
  end

  private

  def set_booking
    @booking = Booking.find(params[:id])
  end

  def set_booking_format
    @booking = Booking.find(params[:format])
  end
  def booking_params
    params.require(:booking).permit(:garden_id, :booker_id, :date)
  end
end

booking.rb

class Booking < ApplicationRecord
  belongs_to :garden
  belongs_to :booker, class_name: "User"
end

花园.rb

class Garden < ApplicationRecord
  belongs_to :user
  has_many :bookings, dependent: :destroy
end

用户.rb

class User < ApplicationRecord
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable
  has_many :gardens
  has_and_belongs_to_many :bookings
end

schema.rb

create_table "bookings", force: :cascade do |t|
    t.date "date"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.bigint "garden_id"
    t.integer "booker_id"
    t.index ["garden_id"], name: "index_bookings_on_garden_id"
 end

  create_table "gardens", force: :cascade do |t|
    t.string "title"
    t.text "details"
    t.integer "surface"
    t.text "address"
    t.bigint "user_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.text "availabilities"
  end

  create_table "users", force: :cascade do |t|
    t.string "email", default: "", null: false
    t.string "encrypted_password", default: "", null: false
    t.string "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.boolean "admin", default: false
    t.index ["email"], name: "index_users_on_email", unique: true
    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
  end

  add_foreign_key "bookings", "gardens"
end

Answer 1

在你的模型中，user.rb：

class User < ApplicationRecord

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable

  has_many :gardens
  has_and_belongs_to_many :bookings
end

:bookings 关联应该是 has_many. 您没有使用连接表。

见：https://guides.rubyonrails.org/association_basics.html#the-has-and-belongs-to-many-association

habtm 关联的belongs_to 部分正在寻找一个不存在的外键。您可以在移动到不同的控制器操作之前检索@booking.booker，因为您根本没有访问数据库，您只是检索实例变量的关联。