Handle null values in findAndModify responses

Author: alcaeus

psalm-baseline.xml

@@ -436,6 +436,7 @@
       <code><![CDATA[$cmd['upsert']]]></code>
       <code><![CDATA[$options['session']]]></code>
       <code><![CDATA[$options['writeConcern']]]></code>
+      <code>$value</code>
     </MixedAssignment>
     <MixedInferredReturnType>
       <code>array|object|null</code>
@@ -445,7 +446,8 @@
       <code>isInTransaction</code>
     </MixedMethodCall>
     <MixedReturnStatement>
-      <code><![CDATA[$this->options['codec']->decode($result->get('value'))]]></code>
+      <code><![CDATA[$value === null ? $value : $this->options['codec']->decode($value)]]></code>
+      <code><![CDATA[$value === null ? $value : $this->options['codec']->decode($value)]]></code>
       <code><![CDATA[is_object($result) ? ($result->value ?? null) : null]]></code>
       <code><![CDATA[is_object($result) ? ($result->value ?? null) : null]]></code>
     </MixedReturnStatement>

src/Operation/FindAndModify.php

@@ -262,7 +262,9 @@ public function execute(Server $server)
             $result = current($cursor->toArray());
             assert($result instanceof Document);
 
-            return $this->options['codec']->decode($result->get('value'));
+            $value = $result->get('value');
+
+            return $value === null ? $value : $this->options['codec']->decode($value);
         }
 
         if (isset($this->options['typeMap'])) {

tests/Operation/FindAndModifyFunctionalTest.php

@@ -296,6 +296,20 @@ public function testFindOneAndDeleteWithCodec(): void
         self::assertEquals(TestObject::createDecodedForFixture(1), $result);
     }
 
+    public function testFindOneAndDeleteNothingWithCodec(): void
+    {
+        // When the query does not match any documents, the operation returns null
+        $operation = new FindAndModify(
+            $this->getDatabaseName(),
+            $this->getCollectionName(),
+            ['remove' => true, 'codec' => new TestDocumentCodec()],
+        );
+
+        $result = $operation->execute($this->getPrimaryServer());
+
+        self::assertNull($result);
+    }
+
     public function testFindOneAndUpdateWithCodec(): void
     {
         $this->createFixtures(1);
@@ -311,6 +325,20 @@ public function testFindOneAndUpdateWithCodec(): void
         self::assertEquals(TestObject::createDecodedForFixture(1), $result);
     }
 
+    public function testFindOneAndUpdateNothingWithCodec(): void
+    {
+        // When the query does not match any documents, the operation returns null
+        $operation = new FindAndModify(
+            $this->getDatabaseName(),
+            $this->getCollectionName(),
+            ['update' => ['$set' => ['x.foo' => 'baz']], 'codec' => new TestDocumentCodec()],
+        );
+
+        $result = $operation->execute($this->getPrimaryServer());
+
+        self::assertNull($result);
+    }
+
     public function testFindOneAndReplaceWithCodec(): void
     {
         $this->createFixtures(1);
@@ -326,6 +354,20 @@ public function testFindOneAndReplaceWithCodec(): void
         self::assertEquals(TestObject::createDecodedForFixture(1), $result);
     }
 
+    public function testFindOneAndReplaceNothingWithCodec(): void
+    {
+        // When the query does not match any documents, the operation returns null
+        $operation = new FindAndModify(
+            $this->getDatabaseName(),
+            $this->getCollectionName(),
+            ['update' => ['_id' => 1], 'codec' => new TestDocumentCodec()],
+        );
+
+        $result = $operation->execute($this->getPrimaryServer());
+
+        self::assertNull($result);
+    }
+
     /**
      * Create data fixtures.
      */