casting

Using CodeIgniter's Custom Casting mechanism

Introduced in CodeIgniter 4 is a nice way to create customized casting to the Entity class. This is exactly what I needed in a project where multiple choices from a UI picker is stored in the database as a comma-separated string but the UI picker component required an array with integers.

Database thus holds "2,5,9" but the UI picker consumes [2,5,9].

Docs

Checking the CodeIgniter docs I came across this information about Custom casting.

Converting data read from the database

I start by extending the BaseCast with my own implementation in the class CastCommaArray:

<?php

namespace App\Entities\Cast;

class CastCommaArray extends \CodeIgniter\Entity\Cast\BaseCast
{

    public static function get($value, array $params = [])
    {
        $p = explode(',', trim($value));
        if (isset($params[0])) {
            if (is_callable($params[0])) {
                $p = array_map($params[0], $p);
            }
        }
        return $p;
    }

    public static function set($value, array $params = [])
    {
        return join(',', $value);
    }

}

The use of $params is required since we have some UI picker elements that require the array to contain strings instead of integers, mainly for picking multiple countries where countries are stored with their ISO-code.

To get all my Entities behaving in the same way I have a class BaseEntitythat I use to extend from. In this base-class I register the Cast Handlers I have created for a couple of special mappings between the database and the UI elements.

<?php

namespace App\Entities;

use App\Entities\Cast\CastBoolean;
use App\Entities\Cast\CastCommaArray;
use App\Entities\Cast\CastPickerAll;

class BaseEntity extends \CodeIgniter\Entity\Entity
{

    protected $castHandlers = [
        'commaarray' => CastCommaArray::class,
        'pickerall'  => CastPickerAll::class,
        'boolean'    => CastBoolean::class
    ];
}

With everything name-spaced correctly I can now use the commaarray casting in my Entity:

<?php

namespace App\Entities;

class PhantomCreditEntity extends BaseEntity
{

    protected $casts = [
        'phantom_credit_id' => 'int',
        'credit_active'     => 'boolean',
        'cert_access'       => 'commaarray[intval]',
        'max_usage'         => 'int',
        'item_version'      => 'int'
    ];

}

In this example, the array should contain integers and I thus pass the extra param intval indicating a callable function to array_map() in the get() function. For the example with country picker, no parameter is passed.

Saving data to the database

When the front-end UI pass an array to the back-end, the set() function is invoked, converting the array to a comma-separated string suitable for storing in the database.