Rails has_many belongs_to 与 foreign_key 和 class_name

Question

我正在尝试为Users 和Messages 的系统建模。 Messages 有 addressers 和 addressees。 Users 有sent_messages 和received_messages。

现在测试失败了，因为它似乎无法找到 addressee_id 和 addresser_id。我想知道我是否正确地对此进行了建模，以及我应该如何通过用户创建消息。

编辑：测试的输出

ActiveRecord::UnknownAttributeError:unknown attribute: addressee_id

在消息规范的 before 语句中弹出。

用户模型

class User < ActiveRecord::Base
  has_many :sent_messages, class_name: "Message", foreign_key: "addresser_id"
  has_many :received_messages, class_name: "Message", foreign_key: "addressee_id" 

消息模型

class Message < ActiveRecord::Base
  validates :addresser_id, presence: true
  validates :addressee_id, presence: true
  belongs_to :addresser, class_name: "User", foreign_key: "addresser_id"
  belongs_to :addressee, class_name: "User", foreign_key: "addressee_id"
end

迁移

class CreateMessages < ActiveRecord::Migration
  def change
    create_table :messages do |t|
      t.string :content     
      t.integer :addresser_id
      t.integer :addressee_id
      t.timestamps
    end
  add_index :messages, [:addressee_id, :addresser_id, :created_at]
  end
end

架构

create_table "messages", force: true do |t|
    t.string   "content"
    t.integer  "addresser"
    t.integer  "addressee"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  add_index "messages", ["addressee", "addresser", "created_at"], name: "index_messages_on_addressee_and_addresser_and_created_at"

message_spec

require 'spec_helper'

describe Message do
  let(:user1) { FactoryGirl.create(:user) }
  let(:user2) { FactoryGirl.create(:user) }
  before { @message = user1.sent_messages.build(content: "Lorem ipsum", addressee_id: user2.id) }

  subject { @message }

  it { should respond_to(:content) }
  it { should respond_to(:addresser_id) }
  it { should respond_to(:addressee_id) }
  its(:addresser) { should eq user1 }

  it { should be_valid }

  describe "when addresser is not present" do
    before { @message.addresser = nil }
    it { should_not be_valid }
  end

  describe "when addressee is not present" do
    before { @message.addressee = nil }
    it { should_not be_valid }
  end
end

Answer 1

尝试替换这个：

describe Message do
  ...
  before { @message = user1.sent_messages.build(content: "Lorem ipsum", addressee_id: user2.id) }
  subject { @message }
  ...
end

有了这个：

describe Message do
  ...
  let(:message){ user1.sent_messages.build(content: "Lorem ipsup", addressee_id: user2.id) }
  subject { message }
  ...
end

还要检查迁移是否在测试环境中运行。

编辑： ActiveRecord::UnknownAttributeError 表示数据库中缺少一列。迁移似乎没问题，但 Message.column_names 的模式和输出却没有。

似乎您的addressee_id / addresser_id实际上在数据库中被命名为addressee / addresser。运行 db:migrate 后是否编辑了迁移文件？

尝试运行 rake db:migrate:redo STEP=1（如果这不是您最后一次迁移，请更改步骤）

Answer 2

我更喜欢这样做

class User < ActiveRecord::Base
  has_many :sent_messages, class_name: "Message", as: :addressor
  has_many :received_messages, class_name: "Message", as: :addressee

和

class Message < ActiveRecord::Base
  belongs_to :addressor, class_name: "User", foreign_key: :addressor_id
  belongs_to :addressee, class_name: "User", foreign_key: :addressee_id