Make it possible to re-order LineItems

[freder]

I need to sort the items in a cart by certain criteria.

I can do that in an adjuster, in which case the response of /actions/commerce/cart/update-cart has to correct order (because it returns the in-memory Order object). however, I also need to persist the custom order, so that the backend, invoice pdf, etc. also use the correct order!

setting $lineItem->dateCreated = /* ... */; does not work because it never actually gets stored in the db again. — the only way to currently do it is to re-implement (and maintain) a slightly different version of saveLineItem() 😞

---

PR: #3130

[brandonkelly]

This would be against existing conventions. For example, craft\services\Elements::saveElement() will only ever set the element record’s dateCreated value for brand new elements:

https://github.com/craftcms/cms/blob/f4aafeece99bab6c1812e34c13612b128ddf486d/src/services/Elements.php#L3013-L3016

So I’d vote against this change.

[freder]

unless you change the value explicitly it would keep it's original value though.
a user wouldn't be able to change it, but a plugin dev could if needed.

alternatively, if changing dateCreated is too hacky, you could provide an official/explicit way to re-order line items.

[freder]

the use case makes sense to you though, right?

[nfourtythree]

This is certainly a good feature request and the ability to have proper control over the order of line items is definitely something we will look into in the future. We will keep this FR open.

In the meantime, you are able to tweak the dateCreated on the LineItem record using the EVENT_BEFORE_INSERT and EVENT_BEFORE_UPDATE on the active record class.

Here is an example of setting every new insert with the date 1970-01-01 01:59:59:

use craft\commerce\records\LineItem;
use yii\base\ModelEvent;

// ...

Event::on(
    LineItem::class,
    LineItem::EVENT_BEFORE_INSERT,
    function(ModelEvent $event) {
        $event->sender->dateCreated = Db::prepareDateForDb(new \DateTime('1970-01-01 01:59:59'));
    }
);

Hope this helps in the short term, thanks!

[freder]

that should work, yes.

---

what I have so far is a bit simpler in that it doesn't require me to figure out the exact date that would insert the line item at the correct position:

Event::on(
	Order::class,
	Order::EVENT_BEFORE_SAVE,
	function (ModelEvent $event) {
		$order = $event->sender;

		// [...] 
		
		// sort the line items
		$lineItemsOrdered = sortCart($order);

		$idx = 0;
		foreach ($lineItemsOrdered as $item) {
			$item->dateCreated = new \DateTime('+' . $idx . ' seconds');
			$item->dateUpdated = $item->dateCreated;
			$idx += 1;
		}
		$order->setLineItems($lineItemsOrdered);

		// [...]

		foreach ($order->getLineItems() as $item) {
			// modified version of https://github.com/craftcms/commerce/blob/5c2f35ea4134f7d234f6e753fb46df0d986c3e0a/src/services/LineItems.php#L205
			saveLineItem($order, $item, false);
		}
	}
);