Rails：除了 has_many 关联之外，如何使用 own_to 关联进行引用？

发布于 2024-11-19 20:01:35 字数 740 浏览 8 评论 0原文

设置如下：一个用户可以有多个地址，但至少其中一个是主地址。用户表中的外键应用作指向主地址记录的指针。

class User < ActiveRecord::Base
  has_many :addresses
  belongs_to :main_address, :class_name => 'Address', :foreign_key => 'main_address_id'

  accepts_nested_attributes_for :main_address
end


class Address < ActiveRecord::Base
  belongs_to :user # used for has_many
end

此设置仅适用于读取 main_address。但构建是一个问题，例如以具有嵌套属性（地址字段）的复杂形式使用它来创建。

我收到以下错误： SQLite3::ConstraintException：addresses.user_id 可能不为 NULL:

问题是，该地址是通过 main_address.build 构建的，并且该地址未接收外键 < code>user_id 因为它是通过 main_address 构建的。

我不知道:( 如何使用belongs_to关联正确引用has_many关联？

原文

Following set-up: A user can have many addresses, but at least one of them is the main address. A foreign key in the user table should be used as a pointer to the main address record.

class User < ActiveRecord::Base
  has_many :addresses
  belongs_to :main_address, :class_name => 'Address', :foreign_key => 'main_address_id'

  accepts_nested_attributes_for :main_address
end


class Address < ActiveRecord::Base
  belongs_to :user # used for has_many
end

This Set-Up works for just reading the main_address. But building is a problem, for example by using it in a complex form with nested attributes (Address fields) for creating.

I get the following error:
SQLite3::ConstraintException: addresses.user_id may not be NULL:

The problem is, that the address is build via main_address.build and the address does not receive the foreign key user_id because it is build via main_address.

I have no idea :(
How can I use a belongs_to association for referencing a has_many association correctly?

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梦魇绽荼蘼 2024-11-26 20:01:35

虽然我同意 lukewendling 的观点，但另一种方法是在 Address 中建立关联（到 User），然后使用 before_save 更新 >user_id 如果需要的话。像这样的东西：

has_one :main_user, :class_name => 'User', :foreign_key => 'main_address_id'

before_save :update_user_id

def update_user_id
  if main_user.present?
    self.user_id = main_user.id
  end
end

Although I agree with lukewendling, the alternative is to establish an association in Address (to User) and then use a before_save to update the user_id if needed. Something like this:

has_one :main_user, :class_name => 'User', :foreign_key => 'main_address_id'

before_save :update_user_id

def update_user_id
  if main_user.present?
    self.user_id = main_user.id
  end
end

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