Rails 通过缺少列命名空间 has_many

Question

在我的 rails 项目中，我有一个命名空间 has_many 通过关系 Scheme

models/school/contact.rb

class School::Contact < ApplicationRecord

  belongs_to :school, class_name: '::School'

  has_many :school_contact_emails, class_name: 'School::Contact::Email'
  has_many :emails, through: :school_contact_emails, class_name: '::Email'

end

models/school/contact/email.rb

class School::Contact::Email < ApplicationRecord
  belongs_to :school_contact, class_name: 'School::Contact'
  belongs_to :email, class_name: '::Email'
end

models/email.rb

class Email < ApplicationRecord
  has_many :school_contact_emails, class_name: 'School::Contact::Email'
  has_many :school_contacts, through: :school_contact_emails, class_name: 'School::Contact'
end

如果我打开 rails 控制台

s = School::Contact.first
=> #<School::Contact id: 1, name: "Headmaster Name", surname: "Headmaster Surname", school_contact_role_id: 1, school_id: 2285, created_at: "2018-06-24 17:47:21", updated_at: "2018-06-24 17:47:21", creator_id: 1, updater_id: 1>

如果我查找电子邮件

s.emails
Traceback (most recent call last):
ActiveRecord::StatementInvalid (PG::UndefinedColumn: ERROR:  column school_contact_emails.contact_id does not exist)

它说 school_contact_emails.contact_id 不存在，但 table 列应该是 "school_contact_id"

这是 School::Contact::Email table

的迁移

class CreateSchoolContactEmails < ActiveRecord::Migration[5.1]
  def change
    create_table :school_contact_emails do |t|
      t.references :school_contact, foreign_key: true
      t.references :email, foreign_key: true

      t.timestamps
      t.userstamps
    end
  end
end

我们将不胜感激任何类型的帮助

Answer 1

你非常接近这个 - Rails 实际上期望外键反映关联对象的名称 class + _id，在这种情况下 contact_id，而不是使用协会本身的名称（在本例中 school_contact）。

这为您提供了两个选择：您可以重命名数据库中的列，或者您可以将 foreign_key 选项添加到您的关联。

例如：

class School::Contact::Email < ApplicationRecord
  belongs_to :school_contact, class_name: 'School::Contact', foreign_key: 'school_contact_id'
  belongs_to :email, class_name: '::Email'
end

希望对您有所帮助 - 如果您有任何问题，请告诉我您的进展情况并大声疾呼。

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