Ruby-on-rails 由于外键约束无法删除对象
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can't delete object due to foreign key constraint
提问by Ricky Mason
Trying to do a simple user.destroybut running into the following error:
试图做一个简单user.destroy但遇到以下错误：
ERROR: update or delete on table "users" violates foreign key constraint "fk_rails_5373344100" on table "identities" DETAIL: Key (id)=(2) is still referenced from table "identities".
错误：更新或删除表“用户”违反了表“身份”上的外键约束“fk_rails_5373344100”详细信息：键（id）=（2）仍然从表“身份”中引用。
Here is my migration for Identities
这是我的身份迁移
class CreateIdentities < ActiveRecord::Migration
def change
create_table :identities do |t|
t.references :user, index: true, foreign_key: true
t.string :provider
t.string :uid
t.timestamps null: false
end
end
end
Here is my user and identity model:
这是我的用户和身份模型：
class Identity < ActiveRecord::Base
belongs_to :user
validates_presence_of :uid, :provider
validates_uniqueness_of :uid, :scope => :provider
def self.find_for_oauth(auth)
find_or_create_by(uid: auth.uid, provider: auth.provider)
end
end
and user:
和用户：
class User < ActiveRecord::Base
TEMP_EMAIL_PREFIX = '[email protected]'
TEMP_EMAIL_REGEX = /\[email protected]/
# Include default devise modules. Others available are:
# :lockable, :timeoutable
devise :database_authenticatable, :registerable, :confirmable,
:recoverable, :rememberable, :trackable, :validatable, :omniauthable
validates_format_of :email, :without => TEMP_EMAIL_REGEX, on: :update
...
end
Im new to foreign keys and references, so I'm not sure at all how to fix this. Any help would be greatly appreciated.
我是外键和引用的新手，所以我完全不知道如何解决这个问题。任何帮助将不胜感激。
Thanks
谢谢
回答by Doon
You would need to remove the Identity that references the user first. Then you can delete the user.. By default the foreign key is doing a restrictso you cannot delete the user if anything references to it.
您需要先删除引用用户的身份。然后您可以删除该用户。默认情况下，外键正在执行 a，restrict因此如果有任何内容引用该用户，您将无法删除该用户。
if you would like use Rails to handle destroying the identity you can do
如果你想使用 Rails 来处理破坏你可以做的身份
class User < ActiveRecord::Base
has_many :identities, dependent: :destroy
......
end
Which would cause Rails to destroy all the dependent records.
这会导致 Rails 销毁所有相关记录。
But as you are using Foreign keys, you can adjust your migration to set cascade deletes
但是当您使用外键时，您可以调整迁移以设置级联删除
add_foreign_key :identities, :users, on_delete: :cascade
Assuming rails 4.2 which has native support
假设 Rails 4.2 具有本机支持
回答by Paul Richter
An easy solution is to simply cascade-delete the records in the associated table, which can be done through active record, like so:
一个简单的解决方案是简单地级联删除关联表中的记录，这可以通过活动记录完成，如下所示：
user.rb
用户名
class User < ActiveRecord::Base
has_many :identities, dependent: :destroy
# rest of user class
end
Check out the documentation pertaining to has_manyfor more info.
查看与 相关has_many的文档以获取更多信息。
