Price and Tax handling / Extend CartProduct / Better totals strategy

[SamBrishes]

The totals / price values which are added using the CartItemPriceAccessors trait are not "jsonable" at the moment, which becomes problematic when used via Rest-API / headless env.

A hotfix I I'm using is the extension of the CartProduct model using a dynamic method

CartProduct::extend(function (CartProduct $model) {
    $model->append('totals');
    $model->addDynamicMethod('getTotalsAttribute', function () use ($model) {
        return [
            'pre_taxes'             => $model->getTotalPreTaxesAttribute(),
            'taxes'                 => $model->getTotalTaxesAttribute(),
            'post_taxes'            => $model->getTotalPostTaxesAttribute(),
            'weight'                => $model->getTotalWeightAttribute(),
            'product_pre_taxes'     => $model->getProductPreTaxesAttribute(),
            'product_taxes'         => $model->getProductTaxesAttribute(),
            'product_post_taxes'    => $model->getProductPostTaxesAttribute(),
        ];
    });
});

The price handling with / without taxes may should be rethinked in general. The designations are confusing and could lead to incorrect expenditure.

Related issues

• Taxes don't take applied discounts into account OFFLINE-GmbH/oc-mall-plugin#423
• Custom field price with multy currency not working OFFLINE-GmbH/oc-mall-plugin#447
• Add price accessors to the product model OFFLINE-GmbH/oc-mall-plugin#12
• [critical bug] wrong tax calculation when vat rate applied on product is different than vat rate applied on shipping OFFLINE-GmbH/oc-mall-plugin#684
• onCheckProductStock event don't take price.official  OFFLINE-GmbH/oc-mall-plugin#938
• Currency format based on country OFFLINE-GmbH/oc-mall-plugin#978
• OrderProduct prices shown in active instead of Order currency OFFLINE-GmbH/oc-mall-plugin#982

[SamBrishes]

Related issue

OFFLINE-GmbH#12