Mapping to entry field with maintain hierarchy breaks unchanged content feature

[ccchapman]

Description

A feed mapping to an entry field which has the maintain hierarchy option enabled breaks the unchanged content feature. In other words, Feed Me will consider the element changed because the "new" content data only contains the leaf.

Expected output

Node `#1` skipped. No content has changed.

Array
(
    [productName] => Vinegar-Champagne Reims
    [productBrand] => Array
        (
            [0] => 30205
        )

    [productCategory] => Array
        (
            [0] => 72444
            [1] => 72487
        )

    [productSku] => X-VIN176C
    [productSize] => 500 ML
)

Processing 1 elements finished in 0.19s

Actual debugging output

productCategory - diff

Array
(
    [0] => Array
        (
            [0] => 72444
            [1] => 72487
        )

    [1] => Array
        (
            [0] => 72487
        )

)

productCategory - existing

Array
(
    [0] => 72444
    [1] => 72487
)

productCategory - new

Array
(
    [0] => 72487
)

Array
(
    [productName] => Vinegar-Champagne Reims
    [productBrand] => Array
        (
            [0] => 30205
        )

    [productCategory] => Array
        (
            [0] => 72487
        )

    [productSku] => X-VIN176C
    [productSize] => 500 ML
)

Processing 1 elements finished in 0.29s

For the time being, I have written a "hack" to workaround the issue.

Expand "hack"

Event::on(
    Process::class,
    Process::EVENT_STEP_BEFORE_ELEMENT_SAVE,
    function (FeedProcessEvent $event) {
        $canonicalElement = $event->element
            ->find()
            ->id($event->element->id)
            ->siteId($event->element->siteId)
            ->one();
        $canonicalCategories = $canonicalElement->productCategory->ids();

        if (
            array_slice($canonicalCategories, -1) !==
            $event->contentData["productCategory"]
        ) {
            return;
        }

        $event->contentData["productCategory"] = $canonicalCategories;
    },
);

Steps to reproduce

1. Create two sections: Products and Product Categories (the latter should be a structure)
2. Create an entry field: Product Category with maintain hierarchy option enabled
3. Create two entries in Product Categories section, the second one nested under the first
4. Create Feed Me feed called Products and setup mapping to Product Category field
5. Process the feed

Additional info

• Craft version: 4.7
• PHP version: 8.3
• Database driver & version: PostgreSQL 14.9
• Plugins & versions: Feed Me 5.4.0

[ccchapman]

Perhaps the contentData needs to be passed through something that will "fill gaps in element" if maintainHierarchy.

[i-just]

Hi, thanks for reporting and clear description! I raised a PR to adjust this.