About daily sequence

[hc2021hc]

Hello, I would like to generate a sequence which renews everyday. Is there any function to do so?
e.g. yyyymmddNN. where NN will start from 01 for each date. Thanks.

[adamchainz]

This should work:

from datetime import datetime, timezone
from sequences import get_next_value
get_next_value(f"books-{datetime.now(timezone.utc).date().isoformat()}")

Swap books for some other domain-related prefix. And think of timezones - this uses UTC which may not apply to your use case!

[hc2021hc]

Sorry I'm new to Python. I would like to ask how I can fallback to previous value if some transaction fails?

say, with transaction.atomic():
get next seq value()
doing sth
save to database

For example, if get_next_value is 2 and save to database fails, I hope the seq can be reverted to 1, how can it be achieved?

[adamchainz]

That should already happen - as the README says:

if the transaction is rolled back, the generated value isn't consumed.

[spapas]

Hey, this is very useful, please put it in the README!

I need a sequence of the form number / year (which will reset each year) and it solves my problem just fine

[adamchainz]

Sure, we could do that, would you like to prepare a PR @spapas ?

[aaugustin]

Indeed, we could add an "Examples" section after "API" and before "Database support".

[spapas]

Hey friends, I've submitted PR #35 with the examples section.

Kind regards,
Serafeim