Rails 引擎中的关联不工作

Question

我正在构建我的第一个 Rails 引擎并且已经很困惑已经定义了两个模型之间的关联。为了方便起见，假设引擎的名称是 Blorg，有两个模型 Article 和 Author.

blorgh/article.rb

module Blorgh
  class Article < ApplicationRecord
    belongs_to :author, class_name: 'Blorg::Author',
                          foreign_key: 'blorg_author_id', optional: true

blorgh/author.rb

module Blorgh
  class Author < ApplicationRecord
    has_many :articles, class_name: 'Blorg::Article'

架构

create_table "blorgh_authors", force: :cascade do |t|
    t.string "name"
    t.boolean "inactive", default: false
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false

create_table "blorgh_articles", force: :cascade do |t|
    t.string "title"
    t.bigint "blorgh_author_id"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.index ["blorgh_author_id"], name: "index_blorgh_article_on_author_id"

如果我尝试通过 rails c 创建文章或计算作者的文章，我会收到这些错误：

article = Blorgh::Article.new(title: 'New Article')
article.save # expect true
# ==> NoMethodError: private method `attribute' called for #<Blorgh::Article:0x00007fdc3fad4d50>

author = Blorgh::Author.create # worked
author.articles.count # expect 0
# ==> ActiveRecord::StatementInvalid: PG::UndefinedColumn: ERROR:  column blorgh_articles.author_id does not exist

有谁知道我如何才能正确实现这些引擎内关联？

Answer 1

第二个错误（“列 blorgh_articles.author_id 不存在”）是因为 Rails 假设 has_many 关系上的外键是 classname_id，在您的示例中为 author_id。您在 belongs_to 侧正确设置了外键，但您需要在关系的两侧指定。所以：

module Blorgh
  class Author < ApplicationRecord
    has_many :articles, class_name: 'Blorg::Article', foreign_key: 'blorg_author_id'
...

Rails 引擎中的关联不工作

Associations within Rails Engine not working

activerecord

ruby-on-rails

associations

rails-engines