Ordering blocks properly

One of the more common tasks in the Loki Checkout is to reposition blocks. This can simply be done by using the XML layout block attributes before and after. However once in a while, you will get stuck with this. Because of this, a lot of the container blocks also offer an attribute sort_order instead.

Take for instance, a field in an address form: Because every field is actually a child block to a parent block of the form, you can simply use the XML layout to customize the way blocks are positioned relative to each other:

<move element="loki.checkout.shipping-step.shipping-address.street0" 
      destination="loki.checkout.shipping-step.address-form" 
      before="loki.checkout.shipping-step.shipping-address.street0"/>

However, if you want the position of street0 to be exactly between 2 other fields, often you will find yourself also repositioning the other fields as well. This quickly becomes a mess. And even worse, because it is not always evident in which order specific layout updates are loaded, it might simply not work.

Using Loki\Components\Util\Block\ChildRenderer instead

Because re-ordering fields is so common, a specific ViewModel Loki\Components\Util\Block\ChildRenderer attempts to make things easier. This ViewModel is inserted into any PHTML template as $childRenderer:

use Loki\Components\Util\Block\ChildRenderer;

/** @var ChildRenderer $childRenderer */

Next, it is used to simply loop through the child blocks where needed:

<?= /* @noEscape */ $childRenderer->all($block); ?>

Re-ordering blocks

By using the XML layout sort_order argument for your block, you can now change the ordering of a specific block:

<referenceBlock name="loki.checkout.shipping-step.shipping-address.street0">
    <arguments>
        <argument name="sort_order" xsi:type="number">2</argument>
    </arguments>
</referenceBlock>

Deprecated class LokiCheckout\Core\Util\Block\SortedBlocks

Earlier the ViewModel class LokiCheckout\Core\Util\Block\SortedBlocks offered the same feature. This class has been deprecated though.