fix(query): the related-row subquery names the prefixed magic table

lib/Service/Query/RelatedRowExistsClause.php

@@ -120,7 +120,7 @@ final class RelatedRowExistsClause {
 	 *
 	 * @param RelatedRowFilter $filter          The parsed filter.
 	 * @param string           $engine          The database engine.
-	 * @param string           $table           The objects table.
+	 * @param string           $table           The related table as SQL names it, `*PREFIX*`-qualified.
 	 * @param string           $outerAlias      The alias of the outer object row.
 	 * @param string           $innerAlias      The alias to give the related row.
 	 * @param string           $accessPredicate SQL restricting the related rows to ones the caller may read.

lib/Service/Query/RelatedRowQueryApplier.php

@@ -123,7 +123,9 @@ public function apply(IQueryBuilder $qb, array $query, Register $register, strin
 			$rendered = $clause->render(
 				filter: $filter,
 				engine: $engine,
-				table: $this->tableHandler->getTableNameForRegisterSchema(register: $register, schema: $schema),
+				// Raw SQL gets no automatic table prefix; Nextcloud's connection
+				// replaces `*PREFIX*` with the instance's (`oc_` by default).
+				table: '*PREFIX*'.$this->tableHandler->getTableNameForRegisterSchema(register: $register, schema: $schema),
 				outerAlias: $outerAlias,
 				innerAlias: $alias,
 				// 🔴 THE ACCESS PREDICATE FOR THE RELATED SCHEMA, NOT THE OUTER

tests/Unit/Service/Query/ReferencedRowFilterTest.php

@@ -130,7 +130,7 @@ public function testTheApplierAddsForwardBlocksWithTheReferencedSchemasOwnAccess
 		$schemaMapper->expects($this->once())->method('findBySlug')->with('subsidieAanvraag', 2)->willReturn([$schema]);
 
 		$tableHandler = $this->createMock(MagicTableHandler::class);
-		$tableHandler->method('getTableNameForRegisterSchema')->willReturn('oc_openregister_table_1_7');
+		$tableHandler->method('getTableNameForRegisterSchema')->willReturn('openregister_table_1_7');
 		$tableHandler->method('existsTableForRegisterSchema')->willReturn(true);
 
 		$rbac = $this->createMock(MagicRbacHandler::class);

tests/Unit/Service/Query/RelatedRowPrefixedDatabaseTest.php

@@ -0,0 +1,154 @@
+<?php
+
+/**
+ * A `_referenced` / `_related` filter run against a real database whose tables carry a prefix.
+ *
+ * The clause tests assert on SQL text, and their doubles returned an already
+ * prefixed table name, so a subquery naming the bare `openregister_table_*`
+ * passed every test and failed on every instance (`oc_` is the default
+ * prefix). This runs the applier's SQL on SQLite with `oc_` tables, after the
+ * `*PREFIX*` replacement Nextcloud's connection performs
+ * (`OC\DB\Connection::replaceTablePrefix()`).
+ *
+ * @category Tests
+ * @package  OCA\OpenRegister\Tests\Unit\Service\Query
+ *
+ * @author    Conduction Development Team <info@conduction.nl>
+ * @copyright 2026 Conduction B.V.
+ * @license   EUPL-1.2 https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12
+ *
+ * @link https://www.OpenRegister.app
+ *
+ * SPDX-License-Identifier: EUPL-1.2
+ * SPDX-FileCopyrightText: 2026 Conduction B.V.
+ */
+
+declare(strict_types=1);
+
+// phpcs:disable PEAR.Commenting.FunctionComment.Missing -- arrange/act/assert PHPUnit conventions.
+// phpcs:disable CustomSniffs.Functions.NamedParameters.RequireNamedParameters -- PHPUnit and DBAL helpers use positional args.
+
+namespace OCA\OpenRegister\Tests\Unit\Service\Query;
+
+use Doctrine\DBAL\Connection;
+use Doctrine\DBAL\DriverManager;
+use OCA\OpenRegister\Db\MagicMapper\MagicRbacHandler;
+use OCA\OpenRegister\Db\MagicMapper\MagicTableHandler;
+use OCA\OpenRegister\Db\Register;
+use OCA\OpenRegister\Db\Schema;
+use OCA\OpenRegister\Db\SchemaMapper;
+use OCA\OpenRegister\Service\Query\RelatedRowQueryApplier;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IDBConnection;
+use PHPUnit\Framework\TestCase;
+use Psr\Log\NullLogger;
+
+/**
+ * @covers \OCA\OpenRegister\Service\Query\RelatedRowQueryApplier
+ * @covers \OCA\OpenRegister\Service\Query\RelatedRowExistsClause
+ */
+class RelatedRowPrefixedDatabaseTest extends TestCase {
+
+	/**
+	 * The instance's table prefix.
+	 *
+	 * @var string
+	 */
+	private const PREFIX = 'oc_';
+
+	/** @var Connection An in-memory SQLite database with prefixed magic tables. */
+	private Connection $db;
+
+	protected function setUp(): void {
+		$this->db = DriverManager::getConnection(['driver' => 'pdo_sqlite', 'memory' => true]);
+
+		// The beschikking table (outer, schema 3) and the aanvraag table (referenced, schema 2).
+		$this->db->executeStatement('CREATE TABLE oc_openregister_table_1_3 (_uuid TEXT, _deleted TEXT, "subsidieaanvraag" TEXT)');
+		$this->db->executeStatement('CREATE TABLE oc_openregister_table_1_2 (_uuid TEXT, _deleted TEXT, _owner TEXT, "case" TEXT)');
+
+		$this->db->executeStatement(
+			'INSERT INTO oc_openregister_table_1_2 (_uuid, _owner, "case") VALUES (\'a-1\', \'alice\', \'case-1\'), (\'a-2\', \'alice\', \'case-2\')'
+		);
+		$this->db->executeStatement(
+			'INSERT INTO oc_openregister_table_1_3 (_uuid, "subsidieaanvraag") VALUES (\'b-1\', \'a-1\'), (\'b-2\', \'a-2\')'
+		);
+	}
+
+	/**
+	 * The applier's clauses for one query, with their parameters.
+	 *
+	 * @param array<string, mixed> $query The request query.
+	 *
+	 * @return array{0: array<int, string>, 1: array<string, mixed>}
+	 */
+	private function clausesFor(array $query): array {
+		$schema = new Schema();
+		$schema->setId(2);
+		$schemaMapper = $this->createMock(SchemaMapper::class);
+		$schemaMapper->method('findBySlug')->willReturn([$schema]);
+
+		// The real handler answers the bare name; the prefix is added in SQL.
+		$tableHandler = $this->createMock(MagicTableHandler::class);
+		$tableHandler->method('getTableNameForRegisterSchema')->willReturn('openregister_table_1_2');
+		$tableHandler->method('existsTableForRegisterSchema')->willReturn(true);
+
+		$rbac = $this->createMock(MagicRbacHandler::class);
+		$rbac->method('buildRbacPredicateForAlias')->willReturn("rel0._owner = 'alice'");
+
+		$where = [];
+		$parameters = [];
+		$qb = $this->createMock(IQueryBuilder::class);
+		$qb->method('createFunction')->willReturnArgument(0);
+		$qb->method('andWhere')->willReturnCallback(function (string $sql) use (&$where, $qb) {
+			$where[] = $sql;
+			return $qb;
+		});
+		$qb->method('setParameter')->willReturnCallback(function (string $name, mixed $value) use (&$parameters, $qb) {
+			$parameters[$name] = $value;
+			return $qb;
+		});
+
+		$register = new Register();
+		$register->setId(1);
+
+		(new RelatedRowQueryApplier(
+			schemaMapper: $schemaMapper,
+			tableHandler: $tableHandler,
+			rbacHandler: $rbac,
+			db: $this->createMock(IDBConnection::class),
+			logger: new NullLogger()
+		))->apply(qb: $qb, query: $query, register: $register);
+
+		return [$where, $parameters];
+	}
+
+	/**
+	 * Run the outer query as Nextcloud's connection would: `*PREFIX*` replaced first.
+	 *
+	 * @param array<int, string>   $where      The clauses.
+	 * @param array<string, mixed> $parameters The bindings.
+	 *
+	 * @return array<int, string> The matching outer uuids.
+	 */
+	private function outerUuidsMatching(array $where, array $parameters): array {
+		$sql = 'SELECT t._uuid FROM *PREFIX*openregister_table_1_3 t WHERE '.implode(' AND ', $where).' ORDER BY t._uuid';
+
+		return $this->db->fetchFirstColumn(str_replace('*PREFIX*', self::PREFIX, $sql), $parameters);
+	}
+
+	public function testAReferencedFilterRunsOnAPrefixedDatabase(): void {
+		[$where, $parameters] = $this->clausesFor(
+			['_referenced' => ['subsidieAanvraag' => ['subsidieaanvraag' => ['case' => 'case-1']]]]
+		);
+
+		$this->assertSame(['b-1'], $this->outerUuidsMatching($where, $parameters));
+	}
+
+	public function testItMatchesNothingWhenNoReferencedRowQualifies(): void {
+		[$where, $parameters] = $this->clausesFor(
+			['_referenced' => ['subsidieAanvraag' => ['subsidieaanvraag' => ['case' => 'case-9']]]]
+		);
+
+		$this->assertSame([], $this->outerUuidsMatching($where, $parameters));
+	}
+}//end class

tests/Unit/Service/Query/RelatedRowQueryApplierTest.php

@@ -63,7 +63,7 @@ private function applierFinding(array $found, bool $tableExists=true): RelatedRo
 		$schemaMapper->method('findBySlug')->willReturn($found);
 
 		$tableHandler = $this->createMock(MagicTableHandler::class);
-		$tableHandler->method('getTableNameForRegisterSchema')->willReturn('oc_openregister_table_1_2');
+		$tableHandler->method('getTableNameForRegisterSchema')->willReturn('openregister_table_1_2');
 		$tableHandler->method('existsTableForRegisterSchema')->willReturn($tableExists);
 
 		$rbac = $this->createMock(MagicRbacHandler::class);