Ecto.Multi without transaction

Questions / Help
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#1

Hi all!

All examples I’ve seen so far wrap Ecto.Multi in transaction to execute - is it possible to run it outside of transaction? That is to use something else (not Repo.transaction) to execute it?

I find error handling provided by Ecto.Multi to be useful but don’t need to rollback previous changes in case further operations fail.

Thanks

#2

Why would you want to do that? The whole point is that it wraps operations in transaction

#3

My use case:

  • insert record (say, user) with pending status
  • make API call
  • update record status to completed in case API call succeeds

If not wrapping operations in transaction everything would be okay but with transaction everything rollbacks and I don’t have any records in users table (I’d like to have the record with pending status to be persisted).

#4

Why not just use regular queries and functions here then? If you do not want transaction semantics (e.g., rollback on failure), do not use a transaction.

#5

As I mentioned error handling provided by Ecto.Multi looks very nice - without it I would have to type lots of case statements to check on each operation result.

Moreover I use Ecto.Multi in similar situations and it fits nicely but in this particular case using transaction is not desirable.

#6

I assume you are familiar with Elixir’s with syntax?

1 Like
#7

Thanks for the hint - using with seems like a decent alternative if Ecto.Multi is not meant to be used without transaction.

#8

I really like Ecto.Multi for composability purposes outside of its intended use case. I think there might be some momentum in the community around this as I’ve heard someone is working on pulling Multi out of Ecto and making it more generic.

I agree with @hubertlepicki. The with syntax is a good alternative. I just went through our code base and replaced a bunch of Ecto.Multi’s with with statements. I’ve recently been down this road and I think using with statements is a good approach.

2 Likes
#9

I’m another in agreement.

My codebase is a mix of Multi Transactions and With statements. It sounds like @tap349 use case is better suited for with. Multi is coupled with database transactions. The API call breaks that pattern. Multi is better with:

  • Insert Record
  • Verify something about record in dB
  • Update record status to completed
#10

You can also check out https://github.com/antonmi/flowex by @antonmi