feat: copyObject() can set new metadata

client.ts

@@ -819,7 +819,11 @@ export class Client {
   public async copyObject(
     source: { sourceBucketName?: string; sourceKey: string; sourceVersionId?: string },
     objectName: string,
-    options?: { bucketName?: string },
+    options?: {
+      bucketName?: string;
+      /** Metadata for the new object. If not specified, metadata will be copied from the source. */
+      metadata?: ObjectMetadata;
+    },
   ): Promise<CopiedObjectInfo> {
     const bucketName = this.getBucketName(options);
     const sourceBucketName = source.sourceBucketName ?? bucketName;
@@ -832,13 +836,13 @@ export class Client {
     let xAmzCopySource = `${sourceBucketName}/${source.sourceKey}`;
     if (source.sourceVersionId) xAmzCopySource += `?versionId=${source.sourceVersionId}`;
 
-    const response = await this.makeRequest({
-      method: "PUT",
-      bucketName,
-      objectName,
-      headers: new Headers({ "x-amz-copy-source": xAmzCopySource }),
-      returnBody: true,
-    });
+    const headers = new Headers(options?.metadata);
+    if (options?.metadata !== undefined) {
+      headers.set("x-amz-metadata-directive", "REPLACE");
+    }
+    headers.set("x-amz-copy-source", xAmzCopySource);
+
+    const response = await this.makeRequest({ method: "PUT", bucketName, objectName, headers, returnBody: true });
 
     const responseText = await response.text();
     // Parse the response XML.

integration.ts

@@ -386,6 +386,40 @@ Deno.test({
   },
 });
 
+Deno.test({
+  name: "copyObject() copies metadata, but we can override it if we want to",
+  fn: async () => {
+    const contents = new Uint8Array([1, 2, 3, 4, 5, 6]);
+    const sourceKey = "test-copy-metadata-source.txt";
+    const destKeySame = "test-copy-metadata-same.txt";
+    const destKeyNew = "test-copy-metadata-new.txt";
+
+    // Create the source file:
+    const metadata = {
+      "Content-Type": "test/custom",
+      "x-amz-meta-custom-key": "custom-value",
+    };
+    await client.putObject(sourceKey, contents, { metadata });
+    // Make sure the destination doesn't yet exist:
+    await client.deleteObject(destKeySame);
+    assertEquals(await client.exists(destKeySame), false);
+
+    // Copy it with the same metadata:
+    await client.copyObject({ sourceKey }, destKeySame);
+    const stat = await client.statObject(destKeySame);
+    assertEquals(stat.metadata, metadata);
+
+    // Copy it with the different metadata:
+    const newMetadata = {
+      "Content-Type": "application/javascript",
+      "x-amz-meta-other": "new",
+    };
+    await client.copyObject({ sourceKey }, destKeyNew, { metadata: newMetadata });
+    const statNew = await client.statObject(destKeyNew);
+    assertEquals(statNew.metadata, newMetadata);
+  },
+});
+
 Deno.test({
   name: "bucketExists() can check if a bucket exists",
   fn: async () => {