More `touch` option for belongs_to?

rubyonrails-core
1

Hi,

I am facing a racing conditions in touch. Let me use this example to explain:

class Order < ApplicationRecord has_many :items end

``

class Item < ApplicationRecord belongs_to :order, touch: true

More relationship:

belongs_to :other_model, touch: true

belongs_to :other_model_2, touch: true

has_many :other_model_3

end

``

For example, I have a one to many relationship, Order has many Items. When an Item get update, it touch Order. Order table has lock_version column, which means Optimistic Locking is enabled.

When some logic update an Item, the relationship will auto trigger touch Order, which has a chance that StaleObjectError error being raised.

The problem is here, coding which modify Item is everywhere. Implement a rescue/retry logic manually in all the places is not a possible solution…

There are many relationship in my project having this touch mechanism. Some of them are even a chain: A touch B touch C touch D.

However, I always have a clear answer in my mind of the question: How important is the touch?

  1. very important, need retry until success.
  2. accuracy is not that important (updated_at datetime value). In this case, if it raise StaleObjectError error, which means someone else has updated the record, right before my touch. So my touch can actually skip. I can write some workaround code like:

class Item < ApplicationRecord belongs_to :order

More relationship:

belongs_to :other_model

belongs_to :other_model_2

has_many :other_model_3

after_commit :touch_all_belongs_to_models

def touch_all_belongs_to_models [order, other_model, other_model_2].each do |model| begin model.touch rescue ActiveRecord::StaleObjectError begin # Reload lock_version in particular. reload rescue ActiveRecord::RecordNotFound # if the record is gone there is nothing to do. else retry end end end end end

Which basically I write my own touch, don’t use Rails build-in solution. A lot more complex.

So I am thinking, maybe we can have more options for touch? Something like:

belongs_to :order, touch: :retry # retry until success.

belongs_to :order, touch: :soft # skip touch if StableObjectError is raise, other modification of records should still save to DB.

``

PS: Sorry for my poor english.

Thanks,

Leonardo