ruby-on-rails - SQLite3::ConstraintException: xxxxx.created_at 不能为 NULL

Question

我有一个创建艺术家并将其与用户关联的 resque 工作。用户 has_and_belongs_to_many :艺术家，艺术家 has_and_belongs_to_many :用户。

def self.perform(itunes_id, user_id=nil)
  artist = Artist.find_by_itunes_id(itunes_id) || lookup_and_create_artist(itunes_id)
  if user_id && user = User.find(user_id)
    user.artists << artist
    user.save!
  end
end

user.artists << artist引发此异常:

ActiveRecord::StatementInvalid: SQLite3::ConstraintException: artists_users.created_at may not be NULL: INSERT INTO "artists_users" ("artist_id", "user_id")

我还看到了一个艺术家_流派的创建(艺术家和流派也有互惠的 HABTM 关系)

ActiveRecord::StatementInvalid: SQLite3::ConstraintException: artists_genres.created_at may not be NULL: INSERT INTO "artists_genres" ("artist_id", "genre_id")

Answer 1

事实证明，这在 Rails 中是有目的的，但已在许多问题中提出:

https://github.com/rails/rails/issues/7732

https://github.com/rails/rails/issues/7735

https://github.com/rails/rails/issues/4653

https://github.com/rails/rails/pull/4682

HABTM 关系不会自动设置时间戳，因此我可以删除它们或使用 has_many :artists, :through => :artists_genres关系