LengthField Field Type

LengthField extends Joomla's ListField to render a <select> populated with every enabled length class from #__j2commerce_lengths. Length classes define the unit of measurement (centimetre, inch, metre, etc.) used on product dimensions. The stored value is the integer primary key j2commerce_length_id.

Class Reference

Property	Value
Class	LengthField
Namespace	J2Commerce\Component\J2commerce\Administrator\Field
File	administrator/components/com_j2commerce/src/Field/LengthField.php
Extends	Joomla\CMS\Form\Field\ListField
Field type token	Length
Since	6.0.7

Database Query

SELECT j2commerce_length_id AS value, length_title AS text
FROM #__j2commerce_lengths
WHERE enabled = 1
ORDER BY length_title ASC

The stored value is j2commerce_length_id (integer).

XML Usage

Basic Usage

<field
    name="length_class_id"
    type="Length"
    label="COM_MYPLUGIN_FIELD_LENGTH_LABEL"
    description="COM_MYPLUGIN_FIELD_LENGTH_DESC"
/>

With Placeholder

<field
    name="length_class_id"
    type="Length"
    label="COM_MYPLUGIN_FIELD_LENGTH_LABEL">
    <option value="0">COM_MYPLUGIN_SELECT_LENGTH</option>
</field>

Supported XML Attributes

Attribute	Type	Description
name	string	Form field name
label	string	Language key for the field label
description	string	Language key for the tooltip
default	integer	Default selected length class ID
required	boolean	Whether a value is required
multiple	boolean	Allow multi-select
class	string	Additional CSS classes on the <select> element

Usage in Plugin Forms

A typical use case is a shipping plugin that needs to know which length unit products are measured in:

<?xml version="1.0" encoding="utf-8"?>
<form addfieldprefix="J2Commerce\Component\J2commerce\Administrator\Field">

    <fieldset name="basic">

        <field
            name="length_class_id"
            type="Length"
            label="COM_MYPLUGIN_FIELD_LENGTH_LABEL"
            description="COM_MYPLUGIN_FIELD_LENGTH_DESC"
            default="0">
            <option value="0">COM_MYPLUGIN_SELECT_LENGTH</option>
        </field>

    </fieldset>

</form>

In a Plugin Manifest <config> Block

<config>
    <fields name="params" addfieldprefix="J2Commerce\Component\J2commerce\Administrator\Field">
        <fieldset name="basic">
            <field
                name="length_class_id"
                type="Length"
                label="COM_MYPLUGIN_LENGTH_LABEL"
                description="COM_MYPLUGIN_LENGTH_DESC"
            />
        </fieldset>
    </fields>
</config>

Source Code

// File: administrator/components/com_j2commerce/src/Field/LengthField.php

declare(strict_types=1);

namespace J2Commerce\Component\J2commerce\Administrator\Field;

use Joomla\CMS\Factory;
use Joomla\CMS\Form\Field\ListField;
use Joomla\CMS\HTML\HTMLHelper;
use Joomla\CMS\Language\Text;
use Joomla\Database\DatabaseInterface;

class LengthField extends ListField
{
    protected $type = 'Length';

    public function getOptions(): array
    {
        $options = parent::getOptions();

        $db    = Factory::getContainer()->get(DatabaseInterface::class);
        $query = $db->getQuery(true)
            ->select([
                $db->quoteName('j2commerce_length_id', 'value'),
                $db->quoteName('length_title', 'text')
            ])
            ->from($db->quoteName('#__j2commerce_lengths'))
            ->where($db->quoteName('enabled') . ' = 1')
            ->order($db->quoteName('length_title') . ' ASC');

        $db->setQuery($query);

        foreach ($db->loadObjectList() as $length) {
            $options[] = HTMLHelper::_('select.option', $length->value, $length->text);
        }

        return $options;
    }
}

Notes

• Length classes are managed under J2Commerce -> Configuration -> Lengths.
• Only classes with enabled = 1 appear. The length_title column stores the human-readable name (e.g., "Centimetre", "Inch").
• Length classes also carry a length_unit abbreviation column (e.g., cm, in) in the database, but the field only exposes length_title as the display label. If you need the unit abbreviation in code, query #__j2commerce_lengths directly by the saved ID.
• Pair with WeightField on product shipping forms.

Related

• WeightField — Weight class dropdown