Add TransactWriteItems

[bartelink]

• Wraps the TransactWriteItems API

  • Basic impl
  • Validate IRL in Equinox Add DynamoDB jet/equinox#321
  • empty request list or >25 items should be rejected with ArgumentOutOfRangeException
    • arguably all such guards should be made consistent herein?
  • Tests
    • passing/failing Check + unconditional PutItem pair
    • Cover presence and absence of all conditions and all actions
    • gathering metrics (not available when check fails)
  • README example

• Adds a Precondition.CheckFailed for trapping normal precondition check fails

[bartelink]

@samritchie This develops bartelink#3
I'm flexible on whether the cleanup PR #47 goes in before or after this (or in some other release)

Will keep chipping away adding tests but would appreciate your thoughts on where to draw the line - ultimately I'm satisfied the basic functionality of the exception filter and the condition checks etc are correct.

After that, the incremental value of validating arbitrary combinations of conditions and individual TransactWrite items becomes more marginal for me. i.e. its duplicating business of the underlying service and/or SDK (which is not the end of the world, but in the context of this repo they should be marked as characterisation tests and/or examples)

[bartelink]

@samritchie I can't think of anything else to do so from my point of view this is ready for final review - let me know if you can see anything that needs doing (in particular, the README is more a braindump than polished tech writing!)

if not, I'll integrate test it when you get a chance to merge and release

[samritchie]

Thanks @bartelink, I'll go through this today - I’m still recovering from the plague and my brain is a bit slow at the moment

[bartelink]

Thanks - I know the feeling so doubly appreciate any time you can carve out in that case.

For reference, here's where it all slots into Equinox (am I glad I have tests over that!) https://github.com/jet/equinox/blob/6a23d9e26aab33b027d7694502415a552e9ce5bb/src/Equinox.DynamoStore/DynamoStore.fs#L417-L468

(And if you think no reasonable person could love that code, contrast it with https://github.com/jet/equinox/blob/6a23d9e26aab33b027d7694502415a552e9ce5bb/src/Equinox.CosmosStore/CosmosStore.fs#L362-L469, which definitely took more development effort and tight-rope walking!)

[bartelink]

Nudge @samritchie - hoping to release a beta of jet/equinox#321 vs having to hand-build some alpha... Even an -alpha Nuget upload would help a lot...

[samritchie]

I'm happy to merge & release this - there’s certainly value here for the single-table crowd.

However this library doesn’t cater particularly well for that pattern & I don’t know how many of those users there are. I expect more than one person will end up wasting time trying to work out out how to do TransactWrite across multiple tables - it feels a little incomplete.

The docs are a bit wordy and are heavy on third party links - have put some comments in there but let’s tidy that up when we have time.

[samritchie]

I'm not overly enthusiastic about the use of things like template.ExtractKey in the tests, purely because new users often look at tests for usage guidance, and I view the record template as internal-ish. Don’t do anything with this for now though, I will have a more general review of the tests.

[bartelink]

Will be interested to see what your alternative is; are you suggesting having a property on the record that calls TableKey.Combined explicitly?

[bartelink]

Thanks for releasing, much appreciated. Your comments are on the money; will circle back on them in the coming days...