ROR - nil class 索引但不显示

Question

我一直试图找到这个问题的答案，但没有任何运气。我想这是一个关联问题，可能是一个新手错误（我就是其中之一）。这是功能：我需要为特定配置文件创建啤酒包（我知道啤酒听起来很有趣，但它让我很难受）

我有 3 个模型：

啤酒模特：

class Beer < ActiveRecord::Base
  include PermissionsConcern
  validates :name, presence: true

  has_many :ratings
  has_many :users, through: :ratings
  has_many :packs
end

个人资料模型：

class Profile < ActiveRecord::Base
  has_many :packs
end

A 包型号：

class Pack < ActiveRecord::Base
  belongs_to :beer
  belongs_to :profile
end

这是packs_controller

class PacksController < ApplicationController
  before_action :set_pack, only: [:show, :edit, :update, :destroy]

def index
  @packs = Pack.all
end

def show
end

def edit
  @beers = Beer.all #Implementación incompleta. Revisar Filtros
  @profiles = Profile.all
end

def create
  @pack = Pack.new(pack_params)
  respond_to do |format|
    if @pack.save
      format.html { redirect_to @pack, notice: 'Pack was successfully created.' }
    else
      format.html { render :new }
    end
  end
end

def update
  respond_to do |format|
    if @pack.update(pack_params)
      format.html { redirect_to @pack, notice: 'Pack was successfully updated.' }
    else
      format.html { render :edit }
     end
  end
end
...

private
  def set_pack
    @pack = Pack.find(params[:id])
  end

  def pack_params
    params.require(:pack).permit(:delivery_date, :profile_id, :beer_id, :status)
  end
end

使用此配置，我遇到以下情况：

我在索引视图中

@packs.each do |p|
p.beer.name #works fine
p.profile.name #brings an "undefined method `name' for nil:NilClass" message
end

在显示视图中我这样做：

@pack.beer.name #works fine.
@pack.profile.name #WORKS FINE ALSO

我在控制台试过，结果是一样的：

Pack.last.profile.name # works fine

Pack.all # works and shows the profile_id correctly.

packs = Pack.all
packs.each do |p|
print p.beer.name #works fine
print p.profile.name #nil class again
end

以防万一我包含架构：

create_table "beers", force: :cascade do |t|
  t.string   "name",               limit: 255
  t.datetime "created_at",                       null: false
  t.datetime "updated_at",                       null: false
  t.string   "beer_type",          limit: 255
end

create_table "packs", force: :cascade do |t|
  t.date     "delivery_date"
  t.integer  "profile_id",    limit: 4
  t.integer  "beer_id",       limit: 4
  t.integer  "status",        limit: 4
  t.datetime "created_at",              null: false
  t.datetime "updated_at",              null: false
end

add_index "packs", ["beer_id"], name: "index_packs_on_beer_id", using: :btree
add_index "packs", ["profile_id"], name: "index_packs_on_profile_id", using: :btree

create_table "profiles", force: :cascade do |t|
  t.string   "ibu_range",  limit: 255
  t.datetime "created_at",             null: false
  t.datetime "updated_at",             null: false
  t.string   "name",       limit: 255
end


add_foreign_key "packs", "beers"
add_foreign_key "packs", "profiles"
end

我尽可能详细地解释了情况。谁能帮我理解我做错了什么？谢谢！！！

Answer 1

有些包可能没有配置文件？

由于您使用的是控制台，请尝试以下操作：

Pack.all.select{|item| item.profile.nil?}.size

如果 size>0 而你不想要这个，那么请添加 validates :profile, presence: true。

ROR - nil class 索引但不显示

ROR - nil class on index but not on show

null

ruby-on-rails

class

associations