Association with primary key is never nullable

Author: ondrejmirtes

src/Rules/Doctrine/ORM/EntityRelationRule.php

@@ -67,11 +67,25 @@ public function processNode(Node $node, Scope $scope): array
 			return [];
 		}
 		$associationMapping = $metadata->associationMappings[$propertyName];
+		$identifier = null;
+		try {
+			$identifier = $metadata->getSingleIdentifierFieldName();
+		} catch (\Throwable $e) {
+			$mappingException = 'Doctrine\ORM\Mapping\MappingException';
+			if (!$e instanceof $mappingException) {
+				throw $e;
+			}
+		}
 
 		$columnType = null;
 		if ((bool) ($associationMapping['type'] & 3)) { // ClassMetadataInfo::TO_ONE
 			$columnType = new ObjectType($associationMapping['targetEntity']);
-			if ($associationMapping['joinColumns'][0]['nullable'] ?? true) {
+			if ($identifier !== null && $identifier === $propertyName) {
+				$nullable = false;
+			} else {
+				$nullable = $associationMapping['joinColumns'][0]['nullable'] ?? true;
+			}
+			if ($nullable) {
 				$columnType = TypeCombinator::addNull($columnType);
 			}
 		} elseif ((bool) ($associationMapping['type'] & 12)) { // ClassMetadataInfo::TO_MANY

tests/Rules/Doctrine/ORM/EntityRelationRuleTest.php

@@ -116,6 +116,21 @@ public function ruleProvider(): Iterator
 					36,
 				],
 			]];
+
+		yield 'primary key as relation' => [
+			__DIR__ . '/data/MyEntityRelationPrimaryKey.php',
+			[],
+		];
+
+		yield 'primary key as nullable relation' => [
+			__DIR__ . '/data/MyEntityRelationNullablePrimaryKey.php',
+			[
+				[
+					'Property PHPStan\Rules\Doctrine\ORM\MyEntityRelationNullablePrimaryKey::$id type mapping mismatch: property can contain PHPStan\Rules\Doctrine\ORM\MyEntity|null but database expects PHPStan\Rules\Doctrine\ORM\MyEntity.',
+					18,
+				],
+			],
+		];
 	}
 
 }

tests/Rules/Doctrine/ORM/data/MyEntityRelationNullablePrimaryKey.php

@@ -0,0 +1,20 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Doctrine\ORM;
+
+use Doctrine\ORM\Mapping as ORM;
+
+/**
+ * @ORM\Entity()
+ */
+class MyEntityRelationNullablePrimaryKey
+{
+	/**
+	 * @ORM\Id()
+	 * @ORM\ManyToOne(targetEntity=MyEntity::class)
+	 *
+	 * @var MyEntity|null
+	 */
+	private $id;
+
+}

tests/Rules/Doctrine/ORM/data/MyEntityRelationPrimaryKey.php

@@ -0,0 +1,20 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Doctrine\ORM;
+
+use Doctrine\ORM\Mapping as ORM;
+
+/**
+ * @ORM\Entity()
+ */
+class MyEntityRelationPrimaryKey
+{
+	/**
+	 * @ORM\Id()
+	 * @ORM\ManyToOne(targetEntity=MyEntity::class)
+	 *
+	 * @var MyEntity
+	 */
+	private $id;
+
+}