错误：表“用户”上的更新或删除违反表“身份”上的外键约束“fk_rails_5373344100”
详细信息：Key(id)=(2)仍然从表“identity”引用.

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

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

和用户：

class User < ActiveRecord::Base
  TEMP_EMAIL_PREFIX = 'ricky@writeit.com'
  TEMP_EMAIL_REGEX = /\ricky@writeit.com/

  # 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

我新的外键和引用,所以我不知道如何解决这个问题.任何帮助将不胜感激.

谢谢