TYPO3 Core

I consider this not as a bug.
A relation to filereference is 1:n by design - also, if max in tca is set to one.

The image property should be defined:

/**
 * @var \TYPO3\CMS\Extbase\Persistence\ObjectStorage<\TYPO3\CMS\Extbase\Domain\Model\FileReference>
 * @lazy
 */
protected $image;

In the fluid template you have to iterate over the image to render the single one or you could use the iteratorFirstVH of vhs.

{namespace v=Tx_Vhs_ViewHelpers}
<v:var.set name="firstImage" value="{v:iterator.first(haystack: images)}" />
<f:image src="{firstImage.uid}" class="{cssClass}" alt="" maxWidth="{settings.imageMaxWidth}" height="{imageHeight}" width="{imageWidth}" treatIdAsReference="TRUE"/>

Marc Bastian Heinrichs wrote:

I consider this not as a bug.
A relation to filereference is 1:n by design - also, if max in tca is set to one.

I tend to agree. It would be consistent.

However, the whole Extbsase persistent can deal with the situation that
the relation is one to one, but the relation is defined on the child (parentKeyFieldName is set).

Besides that, what makes it now break is the caching introduced in #53514

So my suggestion would be to let the method mapObjectToClassProperty() deal with that
and act accordingly.

Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/27949

Sorry Xavier, misinterpreted the whole thing.
Of course the example with a 1:1 relation with irre
worked before introducing the cache in #53514.

Thanks for finding this bug! :-)