On 2/3/19 5:24 AM, Simon Van Casteren wrote:
I'm wondering if there is a way to explicitly ask for a sql rollback.
I think the only way you can now trigger a rollback would be by
calling the "error" function and providing an xbody.
I have two use cases for which I think an explicit rollback mechanism
(not sure how that would look like) would be handy. My main use case
is rolling back everything when a validation is not ok. I don't use
the "error" function because I can't return structured error messages.
When I save some form with 5 fields, I mostly return an error object
with the same 5 fields, so I can provide precise feedback to the user.
Having to clean up all my sql work is huge drag and a source of subtle
bugs.
Let me check that I understand: you want a transaction to return a
structured value that will actually be processed further by legit code,
say the client-side code that has called your server-side RPC? However,
you will undo all database effects, so that the transaction that leaked
a result back to legit code that is now "apocryphal" in terms of
database effects? Wouldn't it be nicer to maintain a data structure in
your RPC handler that batches all database updates until you are sure
you really want to run them? I wouldn't expect to see it complicate the
code much. In fact, I would naturally write database updates /after/
all validation, so that no special code complication is needed.
My second use case is testing with the database. I know some people
frown upon incorporating the database into your tests, but I think
that's silly so I'll ignore that. If have quite some tests that load
stuff into the database as a setup step, then run some tricky query
procedure, check the results, and then clear the DB again. This last
step is again a big annoyance and a source of incorrectly failing tests.
I actually never use automated tests myself, but, if you do, they
probably want to start each test with a predictable, pristine database
state, and likely very small states suffice, right? So then why not
make your testing harness manage all this business outside of Ur/Web?
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