Laravel 5.4+ integer sequence helpers

This package provides helpers to work with no-gap and ordered integer sequences in Laravel models.

It has been built to help the generation of "administrative sequences" where there should be no missing value between records (invoices, etc).

WARNING This is beta version (POC). This is not yet production ready, so you should use at your own risk.

Installation

Add the service provider to your configuration :

'providers' => [
        // ...

        Bnb\Laravel\Sequence\SequenceServiceProvider::class,

        // ...
],

Configuration

You can customize this package behavior by publishing the configuration file :

php artisan vendor:publish --provider='Bnb\Laravel\Sequence\SequenceServiceProvider'

You can customize values without publishing by specifying those keys in your .env file :

SEQUENCE_START=123                      # defaults to 1
SEQUENCE_QUEUE_CONNECTION=database      # defaults to default
SEQUENCE_QUEUE_NAME=sequence            # defaults to default
SEQUENCE_AUTO_DISPATCH=false            # defaults to true

To avoid concurrency issues when generating sequence number, the queue worker number should be set to one. It is recommended to use a dedicated queue (and worker).

Adding a sequence to a model

Sequence columns should be generated with the following configuration in your migration :

$table->unsignedInteger('sequence_name')->nullable()->unique();

To work with sequence you must enhance your model class with the Bnb\Laravel\Sequence\HasSequence trait.

The sequences array property of your model must contain the list of the sequences names :

    public $sequences = ['my_sequence'];

Some sequence properties can be overridden by specifying a method in the model class (where MySequence is the name your sequence in PascalCase) :

• sequence start value (per-sequence) with the getMySequenceStartValue() : int
• sequence format (per-sequence) with the formatMySequenceSequence($next, $last) : int
• sequence generation authorization (per-sequence) with the canGenerateMySequenceSequence() : bool
• sequence gap filling mode (per-sequence) isMySequenceGapFilling() : bool
• sequence generation queue connection (for the model class) getSequenceConnection() : string
• sequence generation queue name (for the model class) getSequenceQueue() : string
• sequence auto-dispatch activation (for the model class) isSequenceAutoDispatch() : bool

Example :

use Bnb\Laravel\Sequence\HasSequence;
use Illuminate\Database\Eloquent\Model;

/**
 * MyModel model uses a sequence named
 */
class MyModel extends Model
{
    use HasSequence;

    const SEQ_INVOICE_NUMBER_START = 0;

    public $timestamps = false;

    protected $fillable = ['active'];

    protected $sequences = ['invoice_number'];

    /**
     * Assume the sequence can only be generated if active is true
     */
    protected function canGenerateReadOnlySequence()
    {
        return $this->active;
    }

    /**
     * The sequence default value must match the format
     */
    protected function getInvoiceNumberStartValue()
    {
        return sprintf('%1$04d%2$06d', date('Y'), static::SEQ_INVOICE_NUMBER_START);
    }


    /**
     * Format the sequence number with current Year that resets its counter to 0 on year change
     */
    protected function formatInvoiceNumberSequence($next, $last)
    {
        $newYear = date('Y');
        $newCounter = substr($next, 4);

        if ($last) {
            $lastYear = substr($last, 0, 4);

            if ($lastYear < $newYear) {
                $newCounter = static::SEQ_INVOICE_NUMBER_START;
            }
        }

        return sprintf('%1$04d%2$06d', $newYear, $newCounter);
    }

    /**
     * If `true`, the first number available is used, ie. the lowest number available, greater or equal to start number, including gaps caused by deletion (soft-delete included)
     * If `false` (default value), the next number will always be the last number used + 1 or the first number of the sequence when nothing pre-exists
     */
    protected function isSequenceGapFilling()
    {
        return false;
    }
}

Sequence generation event

When a sequence number is generated a model event is thrown for running custom tasks. You can listen to the sequence event using the sequenceGenerated($sequenceName, $callback) method (in a service provider boot method for example) :

    MyModel::sequenceGenerated('invoice_number', function ($model) {
        Mail::to($model->recipient_email)->send(new InvoiceGenerated($model));
    });

Schedule generation

You can schedule inside your console kernel the Bnb\Laravel\Sequence\Console\Commands\UpdateSequence at the required frequency to generate the missing sequence numbers asynchronously.

    protected function schedule(Schedule $schedule)
    {
        $schedule->command('sequence:update')
                 ->hourly();
    }

This may not be required when using auto dispatch mode but can be used as a security fallback.