Improved handling of zero-length slices in the pagination adapters

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Fix the Twig view reusing the template from a previous render's options when no default template is configured
 - Fix the template views reusing the options from a previous render
 - Add support for `ruflin/elastica` 9.x
+- [#66](https://github.com/BabDev/Pagerfanta/issues/66) Improved handling of zero-length slices in the pagination adapters
 
 ## 4.9.0 (2026-09-08)
 

lib/Adapter/Doctrine/Collections/SelectableAdapter.php

@@ -40,6 +40,10 @@ public function getNbResults(): int
      */
     public function getSlice(int $offset, int $length): iterable
     {
+        if (0 === $length) {
+            return [];
+        }
+
         return $this->selectable->matching($this->createCriteria($offset, $length));
     }
 

lib/Adapter/Doctrine/Collections/Tests/CollectionAdapterTest.php

@@ -38,4 +38,10 @@ public function testGetResultsShouldReturnTheCollectionSliceReturnValue(): void
 
         $this->assertSame(array_values(range(6, 17)), array_values($slice));
     }
+
+    public function testGetSliceWithZeroLength(): void
+    {
+        $this->assertSame([], $this->adapter->getSlice(0, 0));
+        $this->assertSame([], $this->adapter->getSlice(5, 0));
+    }
 }

lib/Adapter/Doctrine/Collections/Tests/SelectableAdapterTest.php

@@ -2,6 +2,7 @@
 
 namespace Pagerfanta\Doctrine\Collections\Tests;
 
+use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\Common\Collections\Criteria;
 use Doctrine\Common\Collections\Order;
@@ -92,4 +93,12 @@ public function testGetSlice(): void
 
         $this->assertSame($slice, $this->adapter->getSlice(10, 20));
     }
+
+    public function testGetSliceWithZeroLength(): void
+    {
+        $adapter = new SelectableAdapter(new ArrayCollection(range(1, 10)), Criteria::create(true));
+
+        $this->assertSame([], [...$adapter->getSlice(0, 0)]);
+        $this->assertSame([], [...$adapter->getSlice(5, 0)]);
+    }
 }

lib/Adapter/Doctrine/DBAL/Tests/QueryAdapterTest.php

@@ -61,6 +61,14 @@ public function testGetSlice(): void
         $this->assertSame($this->qb->executeQuery()->fetchAllAssociative(), $adapter->getSlice($offset, $length));
     }
 
+    public function testGetSliceWithZeroLength(): void
+    {
+        $adapter = new QueryAdapter($this->qb, static fn (QueryBuilder $qb): QueryBuilder => $qb);
+
+        $this->assertSame([], $adapter->getSlice(0, 0));
+        $this->assertSame([], $adapter->getSlice(30, 0));
+    }
+
     public function testTheAdapterUsesAClonedQuery(): void
     {
         $adapter = $this->createAdapterToTestGetNbResults();

lib/Adapter/Doctrine/DBAL/Tests/SingleTableQueryAdapterTest.php

@@ -56,4 +56,10 @@ public function testGetSlice(): void
 
         $this->assertSame($q->executeQuery()->fetchAllAssociative(), $this->adapter->getSlice($offset, $length));
     }
+
+    public function testGetSliceWithZeroLength(): void
+    {
+        $this->assertSame([], $this->adapter->getSlice(0, 0));
+        $this->assertSame([], $this->adapter->getSlice(30, 0));
+    }
 }

lib/Adapter/Doctrine/MongoDBODM/AggregationAdapter.php

@@ -41,6 +41,10 @@ public function getNbResults(): int
      */
     public function getSlice(int $offset, int $length): iterable
     {
+        if (0 === $length) {
+            return [];
+        }
+
         $aggregationBuilder = clone $this->aggregationBuilder;
 
         return $aggregationBuilder

lib/Adapter/Doctrine/MongoDBODM/QueryAdapter.php

@@ -40,6 +40,10 @@ public function getNbResults(): int
      */
     public function getSlice(int $offset, int $length): iterable
     {
+        if (0 === $length) {
+            return [];
+        }
+
         return $this->queryBuilder->limit($length)
             ->skip($offset)
             ->getQuery()

lib/Adapter/Doctrine/MongoDBODM/Tests/AggregationAdapterTest.php

@@ -109,4 +109,14 @@ public function testGetSlice(): void
 
         $this->assertSame($slice, $this->adapter->getSlice($offset, $length));
     }
+
+    public function testGetSliceWithZeroLengthDoesNotExecuteTheAggregation(): void
+    {
+        // MongoDB rejects a $limit stage of 0, so the adapter must not run the aggregation
+        $this->aggregationBuilder->expects($this->never())
+            ->method('skip');
+
+        $this->assertSame([], $this->adapter->getSlice(0, 0));
+        $this->assertSame([], $this->adapter->getSlice(10, 0));
+    }
 }

lib/Adapter/Doctrine/MongoDBODM/Tests/QueryAdapterTest.php

@@ -88,4 +88,17 @@ public function testGetSlice(): void
 
         $this->assertSame($slice, $this->adapter->getSlice($offset, $length));
     }
+
+    public function testGetSliceWithZeroLengthDoesNotExecuteTheQuery(): void
+    {
+        // A limit of 0 means "no limit" to MongoDB, so the adapter must not run the query
+        $this->queryBuilder->expects($this->never())
+            ->method('limit');
+
+        $this->queryBuilder->expects($this->never())
+            ->method('getQuery');
+
+        $this->assertSame([], $this->adapter->getSlice(0, 0));
+        $this->assertSame([], $this->adapter->getSlice(10, 0));
+    }
 }

lib/Adapter/Doctrine/PHPCRODM/QueryAdapter.php

@@ -38,6 +38,10 @@ public function getNbResults(): int
      */
     public function getSlice(int $offset, int $length): iterable
     {
+        if (0 === $length) {
+            return [];
+        }
+
         return $this->queryBuilder->getQuery()
             ->setMaxResults($length)
             ->setFirstResult($offset)

lib/Adapter/Doctrine/PHPCRODM/Tests/QueryAdapterTest.php

@@ -73,4 +73,13 @@ public function testGetSlice(): void
 
         $this->assertSame($slice, $this->adapter->getSlice($offset, $length));
     }
+
+    public function testGetSliceWithZeroLengthDoesNotExecuteTheQuery(): void
+    {
+        $this->queryBuilder->expects($this->never())
+            ->method('getQuery');
+
+        $this->assertSame([], $this->adapter->getSlice(0, 0));
+        $this->assertSame([], $this->adapter->getSlice(10, 0));
+    }
 }

lib/Adapter/Elastica/Tests/ElasticaAdapterTest.php

@@ -68,6 +68,20 @@ public function testGetSlice(): void
         $this->assertSame($this->resultSet, $this->adapter->getResultSet());
     }
 
+    /**
+     * A zero size is valid for Elasticsearch, and the search must still run so the result set (i.e. aggregations) is available.
+     */
+    public function testGetSliceWithZeroLength(): void
+    {
+        $this->searchable->expects($this->once())
+            ->method('search')
+            ->with($this->query, ['from' => 0, 'size' => 0, 'option1' => 'value1', 'option2' => 'value2'])
+            ->willReturn($this->resultSet);
+
+        $this->assertSame($this->resultSet, $this->adapter->getSlice(0, 0));
+        $this->assertSame($this->resultSet, $this->adapter->getResultSet());
+    }
+
     /**
      * Returns the number of results before search, use count() method if resultSet is empty.
      */

lib/Adapter/Solarium/Tests/SolariumAdapterTest.php

@@ -104,6 +104,36 @@ public function testGetSlice(): void
         $this->assertSame($result, $adapter->getSlice(1, 200));
     }
 
+    /**
+     * A zero row count is valid for Solr, and the query must still run so the result set (i.e. facets) is available.
+     */
+    public function testGetSliceWithZeroLength(): void
+    {
+        $query = $this->createQueryMock();
+        $query->expects($this->once())
+            ->method('setStart')
+            ->with(0)
+            ->willReturnSelf();
+
+        $query->expects($this->once())
+            ->method('setRows')
+            ->with(0)
+            ->willReturnSelf();
+
+        $result = $this->createResultMock();
+
+        $client = $this->createClientMock();
+        $client->expects($this->once())
+            ->method('select')
+            ->with($query)
+            ->willReturn($result);
+
+        $adapter = new SolariumAdapter($client, $query);
+
+        $this->assertSame($result, $adapter->getSlice(0, 0));
+        $this->assertSame($result, $adapter->getResultSet());
+    }
+
     public function testGetSliceCannotUseACachedResultSet(): void
     {
         $query = $this->createQueryStub();

lib/Core/Adapter/ConcatenationAdapter.php

@@ -106,6 +106,11 @@ public function getSlice(int $offset, int $length): iterable
                 $fetchLength = $adapterNbResults - $fetchOffset;
             }
 
+            // The adapter has nothing to contribute to the requested range (i.e. it has no results) — skip it
+            if ($fetchLength <= 0) {
+                continue;
+            }
+
             // Getting the subslice from the adapter and adding it to the result slice
             $fetchSlice = $adapter->getSlice($fetchOffset, $fetchLength);
 

lib/Core/Tests/Adapter/ArrayAdapterTest.php

@@ -47,4 +47,10 @@ public function testGetSlice(int $offset, int $length): void
     {
         $this->assertSame(\array_slice($this->array, $offset, $length), $this->adapter->getSlice($offset, $length));
     }
+
+    public function testGetSliceWithZeroLength(): void
+    {
+        $this->assertSame([], $this->adapter->getSlice(0, 0));
+        $this->assertSame([], $this->adapter->getSlice(50, 0));
+    }
 }

lib/Core/Tests/Adapter/ConcatenationAdapterTest.php

@@ -91,4 +91,34 @@ public function testGetResultsWithTraversableAdapter(): void
         $this->assertSame([2, 3], $adapter->getSlice(1, 2));
         $this->assertSame([4, 5, 6], $adapter->getSlice(3, 3));
     }
+
+    public function testGetSliceWithZeroLength(): void
+    {
+        $adapter = new ConcatenationAdapter([
+            new ArrayAdapter([1, 2, 3]),
+            new ArrayAdapter([4, 5, 6]),
+        ]);
+
+        $this->assertSame([], $adapter->getSlice(0, 0));
+        $this->assertSame([], $adapter->getSlice(3, 0));
+    }
+
+    public function testGetSliceDoesNotRequestAZeroLengthSliceFromAnAdapterWithoutResults(): void
+    {
+        $emptyAdapter = new CallbackAdapter(
+            static fn () => 0,
+            function (int $offset, int $length): iterable {
+                $this->fail(\sprintf('The adapter without results should not be sliced, requested offset %d and length %d.', $offset, $length));
+            }
+        );
+
+        $adapter = new ConcatenationAdapter([
+            new ArrayAdapter([1, 2, 3]),
+            $emptyAdapter,
+            new ArrayAdapter([4, 5, 6]),
+        ]);
+
+        $this->assertSame([3, 4, 5], $adapter->getSlice(2, 3));
+        $this->assertSame([1, 2, 3, 4, 5, 6], $adapter->getSlice(0, 10));
+    }
 }

lib/Core/Tests/Adapter/NullAdapterTest.php

@@ -42,6 +42,14 @@ public function testGetSliceShouldReturnANullArrayWithTheRemainCountWhenLengthIs
         $this->assertSame($this->createNullArray(3), $adapter->getSlice(30, 10));
     }
 
+    public function testGetSliceShouldReturnAnEmptyArrayWithZeroLength(): void
+    {
+        $adapter = new NullAdapter(10);
+
+        $this->assertSame([], $adapter->getSlice(0, 0));
+        $this->assertSame([], $adapter->getSlice(5, 0));
+    }
+
     /**
      * @param int<0, max> $length
      *

lib/Core/Tests/Adapter/TransformingAdapterTest.php

@@ -37,6 +37,11 @@ public function testGetSlice(): void
         $this->assertSame(['0 => 4', '1 => 5'], [...$this->adapter->getSlice(3, 2)]);
     }
 
+    public function testGetSliceWithZeroLength(): void
+    {
+        $this->assertSame([], [...$this->adapter->getSlice(0, 0)]);
+    }
+
     public function testCreateFromInvokable(): void
     {
         $this->adapter = new TransformingAdapter(

phpstan-baseline.neon

@@ -84,12 +84,6 @@ parameters:
 			count: 1
 			path: lib/Adapter/Solarium/SolariumAdapter.php
 
-		-
-			message: '#^Parameter \#2 \$length of method Pagerfanta\\Adapter\\AdapterInterface\<T\>\:\:getSlice\(\) expects int\<0, max\>, int given\.$#'
-			identifier: argument.type
-			count: 1
-			path: lib/Core/Adapter/ConcatenationAdapter.php
-
 		-
 			message: '#^Property Pagerfanta\\Adapter\\ConcatenationAdapter\<T\>\:\:\$adaptersNbResultsCache \(list\<int\<0, max\>\>\|null\) does not accept non\-empty\-array\<int\<0, max\>, int\<0, max\>\>\.$#'
 			identifier: assign.propertyType