feat(storage): add delete object contexts sample

storage/src/delete_object_contexts.php

@@ -0,0 +1,66 @@
+<?php
+/**
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * For instructions on how to run the full sample:
+ *
+ * @see https://github.com/GoogleCloudPlatform/php-docs-samples/tree/main/storage/README.md
+ */
+
+namespace Google\Cloud\Samples\Storage;
+
+# [START storage_delete_object_contexts]
+use Google\Cloud\Storage\StorageClient;
+
+/**
+ * Delete all custom contexts from an existing object.
+ *
+ * @param string $bucketName The name of your Cloud Storage bucket.
+ *        (e.g. 'my-bucket')
+ * @param string $objectName The name of your Cloud Storage object.
+ *        (e.g. 'my-object')
+ */
+function delete_object_contexts(string $bucketName, string $objectName): void
+{
+    $storage = new StorageClient();
+    $bucket = $storage->bucket($bucketName);
+    $object = $bucket->object($objectName);
+
+    // Fetch the current metageneration so the update can be made conditional.
+    $info = $object->info();
+
+    // To delete all contexts, set the 'custom' key to null, which is sent as a
+    // JSON null and clears every context. Do not use an empty PHP array: it
+    // serializes as a JSON list ([]) rather than an empty map.
+    // Optional: set a metageneration-match precondition to avoid potential
+    // race conditions and data corruptions. The request to update is aborted
+    // if the object's metageneration does not match your precondition.
+    $object->update([
+        'contexts' => [
+            'custom' => null,
+        ],
+    ], [
+        'ifMetagenerationMatch' => $info['metageneration'],
+    ]);
+
+    printf('Deleted object contexts for object %s in bucket %s.' . PHP_EOL, $objectName, $bucketName);
+}
+# [END storage_delete_object_contexts]
+
+// The following 2 lines are only needed to run the samples
+require_once __DIR__ . '/../../testing/sample_helpers.php';
+\Google\Cloud\Samples\execute_sample(__FILE__, __NAMESPACE__, $argv);

storage/test/ObjectsTest.php

@@ -77,12 +77,15 @@ public function testObjectContexts()
         ]);
         $this->assertStringContainsString("Found object: $objectInfo", $listOutput);
 
-        // Clear all contexts on the object.
-        $object->update([
-            'contexts' => [
-                'custom' => null,
-            ],
+        // Delete all contexts on the object.
+        $deleteOutput = $this->runFunctionSnippet('delete_object_contexts', [
+            $bucketName,
+            $objectInfo,
         ]);
+        $this->assertStringContainsString(
+            "Deleted object contexts for object $objectInfo in bucket $bucketName.",
+            $deleteOutput
+        );
         $object->reload();
 
         $clearedGetOutput = $this->runFunctionSnippet('get_object_contexts', [