Allow defining a limit and offset for getObjectIdsForTags

lib/private/systemtag/systemtagobjectmapper.php

@@ -95,7 +95,7 @@ class SystemTagObjectMapper implements ISystemTagObjectMapper {
 	/**
 	 * {@inheritdoc}
 	 */
-	public function getObjectIdsForTags($tagIds, $objectType) {
+	public function getObjectIdsForTags($tagIds, $objectType, $limit = 0, $offset = '') {
 		if (!is_array($tagIds)) {
 			$tagIds = [$tagIds];
 		}
@@ -105,10 +105,21 @@ class SystemTagObjectMapper implements ISystemTagObjectMapper {
 		$query = $this->connection->getQueryBuilder();
 		$query->select($query->createFunction('DISTINCT(`objectid`)'))
 			->from(self::RELATION_TABLE)
-			->where($query->expr()->in('systemtagid', $query->createParameter('tagids')))
-			->andWhere($query->expr()->eq('objecttype', $query->createParameter('objecttype')))
-			->setParameter('tagids', $tagIds, IQueryBuilder::PARAM_INT_ARRAY)
-			->setParameter('objecttype', $objectType);
+			->where($query->expr()->in('systemtagid', $query->createNamedParameter($tagIds, IQueryBuilder::PARAM_INT_ARRAY)))
+			->andWhere($query->expr()->eq('objecttype', $query->createNamedParameter($objectType)));
+
+		if ($limit) {
+			if (sizeof($tagIds) !== 1) {
+				throw new \InvalidArgumentException('Limit is only allowed with a single tag');
+			}
+
+			$query->setMaxResults($limit)
+				->orderBy('objectid', 'ASC');
+
+			if ($offset !== '') {
+				$query->andWhere($query->expr()->gt('objectid', $query->createNamedParameter($offset)));
+			}
+		}
 
 		$objectIds = [];
 

lib/public/systemtag/isystemtagobjectmapper.php

@@ -57,15 +57,19 @@ interface ISystemTagObjectMapper {
 	 *
 	 * @param string|array $tagIds Tag id or array of tag ids.
 	 * @param string $objectType object type
+	 * @param int $limit Count of object ids you want to get
+	 * @param string $offset The last object id you already received
 	 *
 	 * @return string[] array of object ids or empty array if none found
 	 *
 	 * @throws \OCP\SystemTag\TagNotFoundException if at least one of the
 	 * given tags does not exist
+	 * @throws \InvalidArgumentException When a limit is specified together with
+	 * multiple tag ids
 	 *
 	 * @since 9.0.0
 	 */
-	public function getObjectIdsForTags($tagIds, $objectType);
+	public function getObjectIdsForTags($tagIds, $objectType, $limit = 0, $offset = '');
 
 	/**
 	 * Assign the given tags to the given object.

tests/lib/systemtag/systemtagobjectmappertest.php

@@ -145,6 +145,42 @@ class SystemTagObjectMapperTest extends TestCase {
 		], $objectIds);
 	}
 
+	public function testGetObjectsForTagsLimit() {
+		$objectIds = $this->tagMapper->getObjectIdsForTags(
+			[$this->tag1->getId()],
+			'testtype',
+			1
+		);
+
+		$this->assertEquals([
+			1,
+		], $objectIds);
+	}
+
+	/**
+	 * @expectedException \InvalidArgumentException
+	 */
+	public function testGetObjectsForTagsLimitWithMultipleTags() {
+		$this->tagMapper->getObjectIdsForTags(
+			[$this->tag1->getId(), $this->tag2->getId(), $this->tag3->getId()],
+			'testtype',
+			1
+		);
+	}
+
+	public function testGetObjectsForTagsLimitOffset() {
+		$objectIds = $this->tagMapper->getObjectIdsForTags(
+			[$this->tag1->getId()],
+			'testtype',
+			1,
+			'1'
+		);
+
+		$this->assertEquals([
+			2,
+		], $objectIds);
+	}
+
 	/**
 	 * @expectedException \OCP\SystemTag\TagNotFoundException
 	 */