Difference between position and sort_order in customer install script

Question

I'm trying to understand how the install works for EAV entities in Magento2.
I see that in the installEntities method from the Magento\Customer\Setup\CustomerSetup class, the attributes have 2 fields with the same value position and sort_order.
but in the catalog module in the Magento\Catalog\Setup\CategorySetup there is only the sort_order field.
Please explain what's the difference between them (if any) and for what is each one used.

Answer 1

I'm pretty sure it's used like an alias but I don't get why both position and sort_order are part of this script.

The only place I've noticed the use of the position in the Customer module is under Magento/Customer/Model/ResourceModel/Setup/PropertyMapper.php :

public function map(array $input, $entityTypeId)
{
    return [
        'is_visible' => $this->_getValue($input, 'visible', 1),
        'is_system' => $this->_getValue($input, 'system', 1),
        'input_filter' => $this->_getValue($input, 'input_filter', null),
        'multiline_count' => $this->_getValue($input, 'multiline_count', 0),
        'validate_rules' => $this->_getValue($input, 'validate_rules', null),
        'data_model' => $this->_getValue($input, 'data', null),
        'sort_order' => $this->_getValue($input, 'position', 0),
        'is_used_in_grid' => $this->_getValue($input, 'is_used_in_grid', 0),
        'is_visible_in_grid' => $this->_getValue($input, 'is_visible_in_grid', 0),
        'is_filterable_in_grid' => $this->_getValue($input, 'is_filterable_in_grid', 0),
        'is_searchable_in_grid' => $this->_getValue($input, 'is_searchable_in_grid', 0),
    ];
}

This method is used to map input attribute properties to storage representation.

It is used in the addAttribute() method in Magento/Eav/Setup/EavSetup.php :

public function addAttribute($entityTypeId, $code, array $attr)
{
    $entityTypeId = $this->getEntityTypeId($entityTypeId);

    $data = array_replace(
        ['entity_type_id' => $entityTypeId, 'attribute_code' => $code],
        $this->attributeMapper->map($attr, $entityTypeId)
    );
    ...
}

However, I don't see this addAttribute() method being called in the Customer install script as it inserts multiple rows at the same time:

    if ($data) {
        $this->getSetup()->getConnection()
            ->insertMultiple($this->getSetup()->getTable('customer_form_attribute'), $data);
    }

Maybe that's the reason why both position and sort_order are specified as the addAttribute() is not called.

Answer 2

It seems the sort_order is the correct one as it is used at \Magento\Eav\Setup\EavSetup::addAttribute.

$sortOrder = isset($attr['sort_order']) ? $attr['sort_order'] : null;

And its also the column name in customer_eav_attribute table.

When looking into catalog_eav_attribute, the position field is always 0. It seems its not used. Even if you change the position value the admin remains unchanged.