Rails：更新时出现“已被占用”错误

Question

应用程序通过属性查找或初始化：

booking = Booking.where(deal_id: params["id"]).first_or_initialize

然后更新一些附加属性

    if booking.update!(
        guests: guests,
        names: names,
        time: time)

这段代码给了我错误

Validation failed: Deal has already been taken

验证码是

  validates_uniqueness_of :deal_id, allow_blank: true, scope: [:experience_id, :time], unless: -> {deal_id.zero? }

为什么第一次执行first_or_initialize时会给出“已被采取”错误？

谢谢

Answer 1

这意味着您在

Booking

、

deal_id

 范围内已经拥有 

experience_id

 和相同的 

time

如果您在将此唯一性验证添加到模型时数据库中已有记录，则可能会发生这种情况

但这根本没有必要。您的

first_or_initialize

仅带有

deal_id

不会妨碍组合

deal_id

、

experience_id

和时间

此外，它不能保护您免受竞争状况影响

您可以在更新之前通过调试检查此类记录计数：

Booking.where(
  deal_id: booking.deal_id,
  experience_id: booking.experience_id,
  time: time,
).count

Answer 2

尝试在没有

update

的情况下运行没有

!

的方法来查看验证失败的地方

result = booking.update(
        guests: guests,
        names: names,
        time: time)
result.errors # <= see related errors here

Answer 3

# This implies the first record
booking = Booking.find_by(deal_id: params["id"])

if booking.nil?
  booking = Booking.new(
    #... your attributes
  )
else
  # Update the attributes you want
  booking.anything = anything
  ...
end

# This will create / update the record in the database

booking.save!