fix: correctly populate ListObjectsResponse.commonPrefixes

Author: lionel-rowe

src/bucket.ts

@@ -274,7 +274,7 @@ export class S3Bucket {
     if (options?.maxKeys) {
       params["max-keys"] = options.maxKeys.toString();
     }
-    if (options?.prefix) {
+    if (options?.prefix != null) {
       params["prefix"] = options.prefix;
     }
     if (options?.continuationToken) {
@@ -360,14 +360,8 @@ export class S3Bucket {
       prefix: extractContent(root, "Prefix"),
       delimiter: extractContent(root, "Delimiter"),
       maxKeys: maxkeys,
-      commonPrefixes: extractField(
-        root,
-        "CommonPrefixes",
-      )?.children.map<CommonPrefix>((prefix) => {
-        return {
-          prefix: extractContent(prefix, "Prefix"),
-        };
-      }),
+      commonPrefixes: extractMultipleFields(root, "CommonPrefixes")
+        .map((node) => ({ prefix: extractContent(node, "Prefix") })),
       encodingType: extractContent(root, "EncodingType"),
       keyCount: keycount,
       continuationToken: extractContent(root, "ContinuationToken"),
@@ -653,6 +647,10 @@ function extractField(node: Xml, name: string): Xml | undefined {
   return node.children.find((node) => node.name === name);
 }
 
+function extractMultipleFields(node: Xml, name: string): Xml[] {
+  return node.children.filter((node) => node.name === name);
+}
+
 function extractContent(node: Xml, name: string): string | undefined {
   const field = extractField(node, name);
   const content = field?.content;

src/response_parsing_test.ts

@@ -0,0 +1,51 @@
+import { assertEquals } from "../test_deps.ts";
+import { S3Bucket } from "./bucket.ts";
+
+const bucket: S3Bucket = Object.create(S3Bucket.prototype)
+
+Deno.test("[response parsing]", async (t) => {
+  await t.step("parseListObjectResponseXml", async (t) => {
+    await t.step("commonPrefixes", () => {
+      // https://docs.aws.amazon.com/AmazonS3/latest/API/API_ListObjectsV2.html#API_ListObjectsV2_Example_8
+      const xml = `<?xml version='1.0' encoding='utf-8' ?>
+        <ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+          <Name>example-bucket</Name>
+          <Prefix>photos/2006/</Prefix>
+          <Marker></Marker>
+          <MaxKeys>1000</MaxKeys>
+          <Delimiter>/</Delimiter>
+          <IsTruncated>false</IsTruncated>
+          <CommonPrefixes>
+            <Prefix>photos/2006/February/</Prefix>
+          </CommonPrefixes>
+          <CommonPrefixes>
+            <Prefix>photos/2006/January/</Prefix>
+          </CommonPrefixes>
+        </ListBucketResult>`;
+
+      assertEquals(bucket["parseListObjectResponseXml"](xml).commonPrefixes, [
+        { prefix: "photos/2006/February/" },
+        { prefix: "photos/2006/January/" },
+      ]);
+    });
+
+    await t.step("commonPrefixes with entity escapes", () => {
+      const xml = `<?xml version='1.0' encoding='utf-8' ?>
+        <ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+          <Name>example-bucket</Name>
+          <Prefix>photos/2006/</Prefix>
+          <Marker></Marker>
+          <MaxKeys>1000</MaxKeys>
+          <Delimiter>/</Delimiter>
+          <IsTruncated>false</IsTruncated>
+          <CommonPrefixes>
+            <Prefix>photos/2006/a&amp;b/</Prefix>
+          </CommonPrefixes>
+        </ListBucketResult>`;
+
+      assertEquals(bucket["parseListObjectResponseXml"](xml).commonPrefixes, [
+        { prefix: "photos/2006/a&b/" },
+      ]);
+    });
+  });
+});

src/types.ts

@@ -243,7 +243,7 @@ export interface ListObjectsResponse {
   /**
    * All of the keys rolled up into a common prefix count as a single return when calculating the number of returns. A response can contain CommonPrefixes only if you specify a delimiter.  CommonPrefixes contains all (if there are any) keys between Prefix and the next occurrence of the string specified by a delimiter.  CommonPrefixes lists keys that act like subdirectories in the directory specified by Prefix. For example, if the prefix is notes/ and the delimiter is a slash (/) as in notes/summer/july, the common prefix is notes/summer/. All of the keys that roll up into a common prefix count as a single return when calculating the number of returns.
    */
-  commonPrefixes?: CommonPrefix[];
+  commonPrefixes: CommonPrefix[];
   /**
    * Encoding type used by Amazon S3 to encode object key names in the XML response. If you specify the encoding-type request parameter, Amazon S3 includes this element in the response, and returns encoded key name values in the following response elements:  Delimiter, Prefix, Key, and StartAfter.
    */