Sqids Elm

Sqids (pronounced "squids") is a small library that lets you generate unique IDs from numbers. It is good for link shortening, fast & URL-safe ID generation and decoding back into numbers for quicker database lookups.

Features:

Encode multiple numbers - generate short IDs from one or several non-negative numbers
Quick decoding - easily decode IDs back into numbers
Unique IDs - generate unique IDs by shuffling the alphabet once
ID padding - provide minimum length to make IDs more uniform
URL safe - auto-generated IDs do not contain common profanity
Randomized output - Sequential input provides nonconsecutive IDs
Many implementations - Support for 40+ programming languages

🧰 Use-cases

Good for:

Generating IDs for public URLs (eg: link shortening)
Generating IDs for internal systems (eg: event tracking)
Decoding for quicker database lookups (eg: by primary keys)

Not good for:

Sensitive data (this is not an encryption library)
User IDs (can be decoded revealing user count)

🚀 Getting started

Install with

elm install sqids/sqids-elm

👩‍💻 Examples

Simple encode & decode:

import Sqids

Sqids.encode [ 1, 2, 3 ]
--> (Ok "86Rf07")

Sqids.decode "86Rf07"
--> (Ok [ 1, 2, 3 ])

If IDs are too short, you can pad them to a certain length:

import Sqids
import Sqids.Context

context : Sqids.Context.Context
context =
    case
        Sqids.Context.from
            { alphabet = Sqids.Context.defaultAlphabet
            , minLength = 10
            , blockList = Sqids.Context.defaultBlockList
            }
    of
        Ok ok ->
            ok

        Err err ->
            Debug.todo <| Debug.toString err

Sqids.encodeWith context [ 1, 2, 3 ]
--> (Ok "86Rf07xd4z")

Sqids.decodeWith context "86Rf07xd4z"
--> (Ok [ 1, 2, 3 ])

Create unique IDs by shuffling the alphabet:

import Sqids
import Sqids.Context

context : Sqids.Context.Context
context =
    case
        Sqids.Context.new
            |> Sqids.Context.withAlphabet "k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt"
            |> Sqids.Context.build
    of
        Ok ok ->
            ok

        Err err ->
            Debug.todo <| Debug.toString err

Sqids.encodeWith context [ 1, 2, 3 ]
--> (Ok "XRKUdQ")

Sqids.decodeWith context "XRKUdQ"
--> (Ok [ 1, 2, 3 ])

Development

You need the Elm compiler and an elm test runner (e.g. elm-test or elm-test-rs).

An easy way to get started is with node.js and elm-tooling.

# Install dependencies
npm install
npx elm-tooling install
# Ensure that no unused code exists or that the documentation comments are correct
npx elm-review --fix
# Run tests in watch mode
npx elm-test-rs --watch

Note: Running elm-review also creates the test file tests/DocumentationCodeSnippetTest.elm to check the code snippets in the README.md file and also the documentation comments in source code.