Any difference between save and save!?

[Andrew Newman]

Hi,

I've been recently been trying to track down a bug that I think is caused by the following code:

Job.transaction do

  job = Job.new

  if job.save

    render status: :ok

  else

    render status: :conflict

  end

end

Is there any important difference (semantically) between that code and the following:

begin

  Job.transaction do

    job = Job.new

    job.save!

    render status: :ok

  end

rescue

  render status: :conflict

end

It seems to me that both approaches won't save to the database unless the validations run successfully.  The only difference I can see in the database log is that the former does a RELEASE SAVEPOINT and the later a ROLLBACK TO SAVEPOINT (when the validations fail).

I'm getting invalid models in the database (Job.find(123).valid? -> false) and I'm pretty sure this is the only code path that creates those models.

[Paul Annesley]

I can't see how either would persist an invalid record.

What database system and table storage engine are you using?
i.e. it's not MySQL + MyISAM, right? Right?

That shouldn't matter, anyway; AR won't attempt to INSERT if the record is invalid.

Your validations don't have `:on => :update` or similar clauses, do they?

The save! bang-method doesn't add much complexity over plain save:

lib/active_record/attribute_methods/dirty.rb
40: def save!(*)
41- super.tap do
42- @previously_changed = changes
43- @changed_attributes.clear
44- end
45- end

lib/active_record/persistence.rb
121: def save!(*)
122- create_or_update || raise(RecordNotSaved)
123- end

lib/active_record/transactions.rb
274: def save!(*) #:nodoc:
275- with_transaction_returning_status { super }
276- end

lib/active_record/validations.rb
56: def save!(options={})
57- perform_validations(options) ? super : raise(RecordInvalid.new(self))
58- end

— Paul

[Jon Rowe]

Probably not related (and you may have simplified your code sample) but that naked rescue clause will rescue all errors and display the conflict page in cases where save might have succeeded but something else has failed…

Do you have callbacks or that could be doing something on save that is being interrupted by the error of a save! ?

Jon Rowe

-----------------------------

ma...@jonrowe.co.uk

jonrowe.co.uk

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[Andrew Newman]

Thanks. I think this is just a case of a missing database constraint (relying on validators only).

http://apidock.com/rails/ActiveRecord/Validations/ClassMethods/validates_uniqueness_of

[Daniel Tsui]

I believe save! raises an exception and save without bang doesn't, which may be relevant if you want your transaction to rollback?