Sequence

The sequence package provides configurable serial number generation with customizable formats and reset policies.

Core Concepts

A sequence consists of:

• Rule: defines the format template and reset policy
• Store: persists the current counter value (database, Redis, or memory)

Sequence Rule

import "github.com/coldsmirk/vef-framework-go/sequence"

rule := sequence.Rule{
    Name:        "order-number",
    Format:      "ORD-{year}{month}{day}-{seq:6}",
    ResetPolicy: sequence.ResetDaily,
}

Format Tokens

Token	Description	Example
{year}	4-digit year	2024
{month}	2-digit month	03
{day}	2-digit day	15
{hour}	2-digit hour	14
{minute}	2-digit minute	30
{second}	2-digit second	05
{seq:N}	Zero-padded sequence number (N digits)	000001

Reset Policies

Policy	Constant	Behavior
Never	sequence.ResetNever	Counter grows indefinitely
Daily	sequence.ResetDaily	Resets at midnight
Monthly	sequence.ResetMonthly	Resets on 1st of each month
Yearly	sequence.ResetYearly	Resets on Jan 1st

Stores

Database Store

Uses the ORM database for persistence — best for most applications:

store := sequence.NewDBStore(db)

Redis Store

Uses Redis for persistence — best for high-throughput scenarios:

store := sequence.NewRedisStore(redisClient)

Memory Store

In-memory storage — for testing only:

store := sequence.NewMemoryStore()

Generating Sequences

generator := sequence.New(rule, store)

// Generate next sequence number
number, err := generator.Next(ctx)
// → "ORD-20240315-000001"

number, err = generator.Next(ctx)
// → "ORD-20240315-000002"

Example Formats

Use Case	Format	Example Output
Order Number	ORD-{year}{month}{day}-{seq:6}	ORD-20240315-000001
Invoice	INV{year}{month}-{seq:4}	INV202403-0001
Document	DOC-{year}-{seq:8}	DOC-2024-00000001
Simple Counter	{seq:10}	0000000001