Custom alphabet produces different results than other libraries

[bcollierjones]

Thank you for getting this off the ground! In doing some playing around I noticed that I got different results when I used a custom alphabet using your library than through the Javascript or Ruby versions.

I used this codepen from Ivan Akimov to test the JS version:
https://codepen.io/ivanakimov/pen/bNmExm

ID: 1 / salt: 'salt' / no custom alphabet - OK
Javascript: XG
Ruby: XG
PL/SQL: XG

ID: 1 / min_length: 6 / salt: 'salt' / no custom alphabet - OK
Javascript: xkXG8Z
Ruby: xkXG8Z
PL/SQL: xkXG8Z

ID: 1 / min_length: 6 / salt: 'salt' / alphabet: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' - ERROR
Javascript: MEPWMP
Ruby: MEPWMP
PL/SQL: JPRAPM

I wish I could offer more assistance.

[andreystepanov]

Thanks for your finding.
I will try to check this bug out!

And you can make a PR, for example :)

[gasi]

First of all, thanks for writing this library. I spent quite some time integrating the plv8 version until I had a hard time getting it running in CI and then learning that AWS RDS doesn’t like either 😉

I noticed the same after setting up a randomized test comparing the JavaScript against this PL/pgSQL implementation: https://github.com/zoomhub/hashids-test/tree/35b61782d13fe5e896f32022ef445b34c764738b#quickstart

The good news: The implementation with default alphabet seems to match 😄

[rutchkiwi]

@andreystepanov did you ever make any headway on this? I would love to use this and was trying to figure out a bugfix but the combination of not being good at plpgsql and not understanding the hashid algorithm makes it very hard..

I don't know what it could be considering that when you pass in the default alphabet explicitly it still returns the same result as the clojure and python implementations.

[braco]

Seems like this PR might fix? #4

[dguo]

For what it's worth, I tested #4 against a significant amount of production data (using a custom alphabet) and compared it to the results from the JavaScript implementation of Hashids. They matched in all cases!