Is the motivation for this documented anywhere? Trying to get up to speed.

Please see PR description in #4577 (comment)

@wojtekmach probably wise to link to the original PR in the body or just copy paste the old PR description here for the next casual passer-by skimming.

@warmwaffles here's a copy-paste of that PR description: (since I can't edit the original 😄)

References:

• tomkonidas.com/repo-transact
• elixirforum.com/t/seeking-thoughts-on-advantages-of-the-repo-transact-pattern-vs-disadvantages-i-ve-read-about-ecto-multi/61733

I believe the interface and implementation are fairly uncontroversial and straightforward. I think the bigger undertaking is potentially revamping the docs, de-emphasizing Multi in favor of this, given that in a lot of (if not the vast majority of) cases, it achieves the same outcomes with less and simpler code. There are no plans to deprecate Multi.

The name of this function is not ideal, some other options considered were Repo.transact and Repo.with_transaction. I think Repo.transaction_with wins because basically:

iex(1)> Repo.transaction<tab>
transaction/1         transaction/2         transaction_with/1    transaction_with/2

That is, it will show up alongside transaction in docs, autocomplete, etc.