SqidEncodeLower

Function SqidEncodeLower( const aValue : Int64; aMinLength : integer) : string

Example

procedure ScriptEvent(var Value: Variant);
begin
  Value := SqidEncodeLower(1001, 8);
  // Value contains lowercase letters/digits and is at least 8 characters.
end;

Usage

SqidEncodeLower encodes a non-negative Int64 as a lowercase-and-digit Sqid with a minimum length.

Parameters

Name	Type	Description
aValue	Int64, const	Non-negative value from 0 through MaxInt64.
aMinLength	integer	Minimum output length from 0 through 255; not an exact or maximum length.

Returns

A non-empty token containing only lowercase a-z and digits 0-9, with length at least aMinLength. SqidDecodeLower reverses it to the original supported value.

Behaviour

• 0 is supported.
• Output is case-sensitive even though it contains no uppercase letters; altering character case makes a token invalid for the paired decoder.
• For a fixed value, minimum, Velox version and blocklist, output is deterministic.
• Minimum length is a lower bound and padding does not affect the decoded value.
• Only one signed Velox value is exposed; the multiple-UInt64 API is not available in scripts.

Errors

Range-check/conversion failures, ESqidsException, allocation errors and script/runtime errors propagate. No fallback token is returned.

Usage notes

Use the lowercase encoder and decoder as a versioned pair. Check permissions on the decoded business object; do not treat possession of a token as authority.

Additional Technical Info

SqidEncodeLower converts one non-negative Int64 to a compact reversible identifier using Velox's fixed lowercase-and-digit Sqids alphabet. It is the fixed-alphabet option for transports that normalise or require lowercase values.

The example is source-reviewed and was not executed by the documentation workflow.

Implementation

Velox converts the signed value to the shipped library's UInt64 and the minimum length to Byte, constructs TSqids with abcdefghijklmnopqrstuvwxyz0123456789 and the shipped default blocklist, and calls EncodeSingle. The library shuffles the alphabet deterministically, encodes the number, pads to the requested minimum when needed and regenerates blocklisted text. The per-call object is freed in a finally block.

Edge cases and quirks

• Negative input is unsupported and raises under the current checked conversion to UInt64.
• Minimum length outside 0..255 raises when converted to the shipped constructor's Byte.
• Output can exceed the requested minimum for large values or due to Sqids structure/blocklist regeneration.
• Changes to the shipped default blocklist can change newly generated tokens for the same value; exhausted regeneration attempts raise.
• Lowercase-only text can still be changed by external systems that trim, truncate or treat identifiers numerically. Store and compare it as an exact string.
• The result is reversible obfuscation, not encryption, a hash, authentication or authorisation.

Side effects

None beyond per-call object and temporary-array allocation.

Performance and concurrency

Ordinary encoding is small, with per-call alphabet/blocklist setup plus possible padding and regeneration. Each call owns its Sqids instance, so independent calls share no mutable instance state.

Related entries

• SqidDecodeLower decodes this exact configuration.
• SqidEncode emits uppercase-and-digit tokens.
• SqidEncodeCustom accepts an explicitly ordered alphabet.

External references

• Sqids FAQ - official guidance on intended use, non-negative values, minimum length, blocklists and reversibility.

Created 2026-07-15