[BUGFIX] Allow maxitems=1 for TCA type category

In relation mode "manyToMany" it is okay to have
a limit of one.

Code-wise the FlexForm code is slightly simplified
as there is no support for the "manytoMany" case.

Resolves: #103188
Releases: main, 12.4, 11.5
Change-Id: Ib2bbafadefc39f603a9ec4fda20aebcee85cdd7a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83090


Tested-by: core-ci <typo3@b13.com>
Tested-by: Josef Glatz <typo3@josefglatz.at>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Josef Glatz <typo3@josefglatz.at>

typo3/sysext/core/Classes/Configuration/FlexForm/FlexFormTools.php

@@ -654,7 +654,7 @@ class FlexFormTools
                         );
                     }
                     $fieldConfig['config']['maxitems'] = 1;
-                } elseif ($fieldConfig['config']['relationship'] === 'oneToMany') {
+                } else {
                     // In case maxitems is not set or set to 0, set the default value "99999"
                     if (!($fieldConfig['config']['maxitems'] ?? false)) {
                         $fieldConfig['config']['maxitems'] = 99999;

typo3/sysext/core/Classes/Configuration/Tca/TcaPreparation.php

@@ -116,7 +116,9 @@ class TcaPreparation
                 } elseif (!($fieldConfig['config']['maxitems'] ?? false)) {
                     // In case maxitems is not set or set to 0, set the default value "99999"
                     $fieldConfig['config']['maxitems'] = 99999;
-                } elseif ((int)($fieldConfig['config']['maxitems'] ?? 0) === 1) {
+                } elseif ($fieldConfig['config']['relationship'] === 'oneToMany'
+                    && (int)($fieldConfig['config']['maxitems'] ?? 0) === 1
+                ) {
                     throw new \RuntimeException(
                         $fieldName . ' of table ' . $table . ' is defined as type category with a ' . $fieldConfig['config']['relationship'] .
                         ' relationship. Therefore, maxitems can not be set to 1. Use oneToOne as relationship instead.',

typo3/sysext/core/Tests/Unit/Configuration/Tca/TcaPreparationTest.php

@@ -251,21 +251,6 @@ final class TcaPreparationTest extends UnitTestCase
 
     public static function configureCategoryRelationsThrowsExceptionOnInvalidMaxitemsDataProvider(): \Generator
     {
-        yield 'No relationship with maxitems=1 (falls back to manyToMany)' => [
-            [
-                'aTable' => [
-                    'columns' => [
-                        'foo' => [
-                            'config' => [
-                                'type' => 'category',
-                                'maxitems' => 1,
-                            ],
-                        ],
-                    ],
-                ],
-            ],
-            1627335017,
-        ];
         yield 'oneToOne relationship with maxitems=2' => [
             [
                 'aTable' => [
@@ -298,22 +283,6 @@ final class TcaPreparationTest extends UnitTestCase
             ],
             1627335017,
         ];
-        yield 'manyToMany relationship with maxitems=1' => [
-            [
-                'aTable' => [
-                    'columns' => [
-                        'foo' => [
-                            'config' => [
-                                'type' => 'category',
-                                'relationship' => 'oneToMany',
-                                'maxitems' => 1,
-                            ],
-                        ],
-                    ],
-                ],
-            ],
-            1627335017,
-        ];
     }
 
     #[Test]