TYPO3 Core

I can confirm that Illias patch seems to be even working for the case I'm having here:

       'config' => array(
                'type' => 'select',
                'renderType' => 'selectMultipleSideBySide',
                'foreign_table' => 'tx_extension_domain_model_xxx',
                'MM' => 'tx_extension_xxx_yyy_mm',
                'itemsProcFunc' => 'Vendor\Extension\TCE\XXX->getOnlySomeOptions',
       ),

I can confirm this fix is working.

On TYPO3 10.3, t3g/blog (latest dev-master) was broken as every time you edited a blog page the author with ID 1 was added.

The MM count "1" (stored in pages[authors]) was added to the items list before loading the related records and appending their UIDs to the items list as well.

The patch being reviewed fixes this misbehavior.

TCA of the affected field:

        'authors' => [
            'exclude' => 1,
            'label' => $ll . 'pages.authors',
            'config' => [
                'type' => 'select',
                'renderType' => 'selectMultipleSideBySide',
                'multiple' => 0,
                'foreign_table' => 'tx_blog_domain_model_author',
                'MM' => 'tx_blog_post_author_mm',
                'minitems' => 0,
                'maxitems' => 99999,
                'behaviour' => [
                    'allowLanguageSynchronization' => true
                ]
            ],
        ],

@Leonie Philine Bitto please use the "Reply" button in the review system to cast your positive vote on the patch if it works for you. Thanks.

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/c/Packages/TYPO3.CMS/+/63758