Question

我有两个由has_many / belongs_to实现的具有多对多关系的模型，如下所示：

this.route
      .queryParamMap
      .map(params => params.get('coordinates'))
      .subscribe(coordinates => this.navigationService.navigateTo(coordinates))

这些表是在以下迁移中创建的：

class Author < ApplicationRecord
  has_many :author_books
  has_many :books, :through => :author_books, :validate => false
end
class Book < ApplicationRecord
  has_many :author_books
  has_many :authors, :through => :author_books, :validate => false
end
class AuthorBook < ApplicationRecord
  belongs_to :author
  belongs_to :book
end

当我执行以下测试代码时：

create_table :books do |t|
  t.string :name
  t.integer :price
end
create_table :authors do |t|
  t.string :name
end
create_table :author_books do |t|
  t.integer :book_id
  t.integer :author_id
  t.integer :percent
end

我得到以下好的结果：

Book.delete_all
Author.delete_all
AuthorBook.delete_all

author1 = Author.create name: 'a1'
author2 = Author.create name: 'a2'

book = Book.new name: 'b', price: 40
book.authors = Author.where("id = #{author1.id} or id = #{author2.id}")
ret = book.save

AuthorBook.all.each do |ab|
  puts "Author id #{ab.id} author #{ab.author_id} book #{ab.book_id}"
end

但是当我将以下Author id 1 author 980190963 book 980190963 Author id 2 author 980190964 book 980190963添加到AuthorBook：

时

after_save

我得到以下好的结果：

after_save :f

def f
  self.book.author_books.each do |ab|
    # nothing
  end
end

事实上，当我检查数据库时，我可以看到AuthorBook记录在其book_id字段中包含nil。知道为什么会这样吗？

Rails在多对多关系上创建非法连接模型记录

0 个答案: