Selectable Assets Condition - Add variables like in Routes and Asset Location

[thisanimus]

Is there any way to use variables from the entry like {slug} in the Selectable Assets Condition section of an Asset field?

[brandonkelly]

Not currently. How would you envision it working exactly?

[thisanimus]

@brandonkelly You know how in Routes and Asset Location fields you can enter a custom path, but also have access to vars like {slug} based on the context? I'd envision it working the same way here. When you're creating a condition, you could use vars available in the current context to limit what assets are displayed in the asset browser.

The use-case for us is we have a section with ~20,000 assets spread across ~10,000 entries. We tried putting each entry's files in its own dir (using the dynamic asset path mentioned above) but trying to render ~10,000 dirs borked the asset browser. The files all follow a naming convention, so we could use data in a given entry to limit what assets are selectable from within that entry.

I know it's pretty niche, but it doesn't hurt to ask right?

[brandonkelly]

Conditions aren’t inherently aware of their context so this wouldn’t really be possible. However you can supply your own custom condition rule from a module, which keeps its own reference to the entry being edited, and filters the assets accordingly.

We’re still working on condition documentation, but here’s what the rule would look like:

namespace mymodulenamespace;

use Craft;
use craft\base\conditions\BaseConditionRule;
use craft\base\ElementInterface;
use craft\elements\conditions\ElementConditionRuleInterface;
use craft\elements\db\AssetQuery;
use craft\elements\db\ElementQueryInterface;

class MyAssetConditionRule extends BaseConditionRule implements ElementConditionRuleInterface
{
    public ?int $editedElementId = null;

    public function getConfig(): array
    {
        $config = parent::getConfig();

        if (Craft::$app->controller instanceof \craft\controllers\ElementsController) {
            $config['editedElementId'] = Craft::$app->controller->element->id ?? null;
        }

        return $config;
    }

    public function getLabel(): string
    {
        return 'Limit based on the entry';
    }

    public function getExclusiveQueryParams(): array
    {
        return [];
    }

    /**
     * @inheritdoc
     */
    public function modifyQuery(ElementQueryInterface $query): void
    {
        if ($this->editedElementId) {
            $element = Craft::$app->elements->getElementById($this->editedElementId);
            if ($element) {
                // Find the folder associated with this entry
                $folder = Craft::$app->assets->findFolder(['path' => $element->slug]);
                if ($folder) {
                    // Limit the query to only that folder and its subfolders
                    /** @var AssetQuery $query */
                    $query->folderId($folder->id)->includeSubfolders();
                }
            }
        }
    }

    /**
     * @inheritdoc
     */
    public function matchElement(ElementInterface $element): bool
    {
        // This condition shouldn't be used on individual assets
        return false;
    }
}

Register the condition rule for use in asset conditions like so:

use craft\elements\conditions\assets\AssetCondition;
use craft\events\RegisterConditionRuleTypesEvent;
use yii\base\Event;

Event::on(
    AssetCondition::class,
    AssetCondition::EVENT_REGISTER_CONDITION_RULE_TYPES,
    function(RegisterConditionRuleTypesEvent $event) {
        $event->conditionRuleTypes[] = MyAssetConditionRule::class;
    }
);

Then from your Assets field, you can select your new condition rule in the Selectable Assets Condition.

(Note that this will require Craft 4.3+, as that’s when craft\controllers\ElementsController::$element was added.)

This won’t solve the performance problem though, which comes from rendering the folder tree. We’re brainstorming ways to improve that, but it’s likely going to require a breaking change so more of a 5.0 thing.

In the meantime, you could hook into the EVENT_REGISTER_SOURCES event to remove the built-in asset source for the volume, and replace it with one that just limits the assets to the volume, but doesn’t bother with representing the full subfolder tree:

use craft\elements\Asset;
use craft\events\RegisterElementSourcesEvent;
use yii\base\Event;

Event::on(
    Asset::class,
    Asset::EVENT_REGISTER_SOURCES,
    function(RegisterElementSourcesEvent $event) {
        $volume = Craft::$app->volumes->getVolumeByHandle('myVolumeHandle');
        if ($volume) {
            // Replace the stock source definition for the volume with a custom
            // one that doesn’t worry about subfolders
            foreach ($event->sources as $i => $source) {
                if ($source['key'] === "volume:$volume->uid") {
                    $event->sources[$i] = [
                        'key' => 'custom-volume',
                        'label' => $volume->name,
                        'hasThumbs' => true,
                        'criteria' => ['volumeId' => $volume->id],
                        'defaultSort' => ['dateCreated', 'desc'],
                    ];
                }
            }
        }
    }
);

[thisanimus]

Wow! fantastic. Thanks for the clear direction!