The right way to add a new field in admin product page in Prestashop 1.7

Question

I've created a module for Prestashop 1.7 in order to add a new field in the Admin Product page. Due to the lack of proper documentation, I want to ask the proper way to add my custom field, a select. I want to get saved and updated on product save.

I use the code below to add a tpl containing a form

public function hookDisplayAdminProductsExtra($params) {
    $this->smarty;

    $available_items = $this->getAvailableBadges();
    $id_product  = Tools::getValue('id_product');

    $this->context->smarty->assign('items_number', $available_items);
    return $this->display(__FILE__, '/views/templates/admin/admin_products.tpl');
}

The problem is that I don't know how to make to override the Product.php Class in order to have my $field and how to create the form element for the tpl.

The form I want to create I something like that

<select name="" id="">
    {foreach from=$items_number item=option}
        <option value="{$option}">
            {$option}
        </option>
    {/foreach}
</select>

Sorry for the lack of information, but I find the new way of creating modules very confusing. Thanks in advance

Answer 1

To override the Product class :

Create a file "Product.php" in override/classes/

and add the following :

//override the class
class Product extends ProductCore {
    //add your attribute
    public $field_name;

    //override the construct function
    public function __construct($id_product = null, $full = false, $id_lang = null, $id_shop = null, \Context $context = null) {

        //add your custom field to the array $definitions['fields']
        self::$definition['fields']['field_name'] = [
            'type' => self::TYPE_STRING,
            'lang' => true, //if you have multiple languages on your site
            'required' => false,
            'size' => 255
        ];
    }
}

Then, add a new entry in your database, "field_name" in ps_product if lang is set to false or in ps_product_lang if lang is set to true.

You have different types : "TYPE_STRING", "TYPE_HTML", "TYPE_BOOL", "TYPE_INT", ... I don't know the exhaustive list. Depending on the type you choose you have to create the right column type in database ("VARCHAR", "TEXT", ....)

Some good documentation can be found in forum (stackoverflow, https://www.prestashop.com/forums/) but also on blog like this one : https://www.h-hennes.fr/blog/