Include prefixes when listing blobs with field selector

gcloud-java-core/src/main/java/com/google/cloud/FieldSelector.java

@@ -43,6 +43,8 @@ public interface FieldSelector {
    */
   class Helper {
 
+    private static final String[] EMPTY_FIELDS = {};
+
     private Helper() {}
 
     private static final Function<FieldSelector, String> FIELD_TO_STRING_FUNCTION =
@@ -63,33 +65,49 @@ private static String selector(List<? extends FieldSelector> required, FieldSele
     }
 
     /**
-     * Returns a composite selector given a number of fields. The string selector returned by this
-     * method can be used for field selection in API calls that return a single resource. This
-     * method is not supposed to be used directly by users.
+     * Returns a composite selector given a number of resource fields. The string selector returned
+     * by this method can be used for field selection in API calls that return a single resource.
+     * This method is not supposed to be used directly by users.
      */
     public static String selector(List<? extends FieldSelector> required, FieldSelector... others) {
       return selector(required, others, new String[]{});
     }
 
     /**
-     * Returns a composite selector given a number of fields and a container name. The string
-     * selector returned by this method can be used for field selection in API calls that return a
-     * list of resources. This method is not supposed to be used directly by users.
+     * Returns a composite selector given a number of resource fields and a container name. The
+     * string selector returned by this method can be used for field selection in API calls that
+     * return a  list of resources. This method is not supposed to be used directly by users.
      */
     public static String listSelector(String containerName, List<? extends FieldSelector> required,
         FieldSelector... others) {
       return "nextPageToken," + containerName + '(' + selector(required, others) + ')';
     }
 
     /**
-     * Returns a composite selector given a number of fields and a container name. This methods also
-     * takes an {@code extraResourceFields} parameter to specify some extra fields as strings. The
-     * string selector returned by this method can be used for field selection in API calls that
-     * return a list of resources. This method is not supposed to be used directly by users.
+     * Returns a composite selector given a number of resource fields and a container name. This
+     * method also takes an {@code extraResourceFields} parameter to specify some extra resource
+     * fields as strings. The string selector returned by this method can be used for field
+     * selection in API calls that return a list of resources. This method is not supposed to be
+     * used directly by users.
      */
     public static String listSelector(String containerName, List<? extends FieldSelector> required,
         FieldSelector[] others, String... extraResourceFields) {
-      return "nextPageToken," + containerName + '('
+      return listSelector(EMPTY_FIELDS, containerName, required, others, extraResourceFields);
+    }
+
+    /**
+     * Returns a composite selector given a number of top level fields as strings, a number of
+     * resource fields and a container name. This method also takes an {@code extraResourceFields}
+     * parameter  to specify some extra resource fields as strings. The string selector returned by
+     * this method can be used for field selection in API calls that return a list of resources.
+     * This method is not supposed to be used directly by users.
+     */
+    public static String listSelector(String[] topLevelFields, String containerName,
+        List<? extends FieldSelector> required, FieldSelector[] others,
+        String... extraResourceFields) {
+      Set<String> topLevelStrings = Sets.newHashSetWithExpectedSize(topLevelFields.length + 1);
+      topLevelStrings.addAll(Lists.asList("nextPageToken", topLevelFields));
+      return Joiner.on(',').join(topLevelStrings) + "," + containerName + '('
           + selector(required, others, extraResourceFields) + ')';
     }
   }

gcloud-java-core/src/test/java/com/google/cloud/FieldSelectorHelperTest.java

@@ -46,6 +46,7 @@ public String selector() {
       return "field3";
     }
   };
+  private static final String[] FIRST_LEVEL_FIELDS = {"firstLevel1", "firstLevel2"};
   private static final List<FieldSelector> REQUIRED_FIELDS = ImmutableList.of(FIELD1, FIELD2);
   private static final String CONTAINER = "container";
 
@@ -81,4 +82,20 @@ public void testListSelectorWithExtraFields() {
     assertTrue(selector.endsWith(")"));
     assertEquals(52, selector.length());
   }
+
+  @Test
+  public void testListSelectorWithFirstLevelFields() {
+    String selector = Helper.listSelector(FIRST_LEVEL_FIELDS, CONTAINER, REQUIRED_FIELDS,
+        new FieldSelector[]{FIELD3}, "field4");
+    assertTrue(selector.contains("firstLevel1"));
+    assertTrue(selector.contains("firstLevel2"));
+    assertTrue(selector.contains("nextPageToken"));
+    assertTrue(selector.contains("container("));
+    assertTrue(selector.contains("field1"));
+    assertTrue(selector.contains("field2"));
+    assertTrue(selector.contains("field3"));
+    assertTrue(selector.contains("field4"));
+    assertTrue(selector.endsWith(")"));
+    assertEquals(76, selector.length());
+  }
 }

gcloud-java-storage/src/main/java/com/google/cloud/storage/Storage.java

@@ -654,6 +654,7 @@ public static BucketListOption fields(BucketField... fields) {
    */
   class BlobListOption extends Option {
 
+    private static final String[] TOP_LEVEL_FIELDS = {"prefixes"};
     private static final long serialVersionUID = 9083383524788661294L;
 
     private BlobListOption(StorageRpc.Option option, Object value) {
@@ -713,7 +714,7 @@ public static BlobListOption versions(boolean versions) {
      */
     public static BlobListOption fields(BlobField... fields) {
       return new BlobListOption(StorageRpc.Option.FIELDS,
-          Helper.listSelector("items", BlobField.REQUIRED_FIELDS, fields));
+          Helper.listSelector(TOP_LEVEL_FIELDS, "items", BlobField.REQUIRED_FIELDS, fields));
     }
   }
 

gcloud-java-storage/src/test/java/com/google/cloud/storage/StorageImplTest.java

@@ -584,12 +584,13 @@ public void testListBucketsWithSelectedFields() {
     initializeService();
     ImmutableList<Bucket> bucketList = ImmutableList.of(expectedBucket1, expectedBucket2);
     Page<Bucket> page = storage.list(BUCKET_LIST_FIELDS);
-    String selector = (String) capturedOptions.getValue().get(BLOB_LIST_FIELDS.rpcOption());
-    assertTrue(selector.contains("items"));
+    String selector = (String) capturedOptions.getValue().get(BUCKET_LIST_FIELDS.rpcOption());
+    assertTrue(selector.contains("items("));
     assertTrue(selector.contains("name"));
     assertTrue(selector.contains("acl"));
     assertTrue(selector.contains("location"));
     assertTrue(selector.contains("nextPageToken"));
+    assertTrue(selector.endsWith(")"));
     assertEquals(38, selector.length());
     assertEquals(cursor, page.nextPageCursor());
     assertArrayEquals(bucketList.toArray(), Iterables.toArray(page.values(), Bucket.class));
@@ -607,10 +608,11 @@ public void testListBucketsWithEmptyFields() {
     initializeService();
     ImmutableList<Bucket> bucketList = ImmutableList.of(expectedBucket1, expectedBucket2);
     Page<Bucket> page = storage.list(BUCKET_LIST_EMPTY_FIELDS);
-    String selector = (String) capturedOptions.getValue().get(BLOB_LIST_FIELDS.rpcOption());
-    assertTrue(selector.contains("items"));
+    String selector = (String) capturedOptions.getValue().get(BUCKET_LIST_EMPTY_FIELDS.rpcOption());
+    assertTrue(selector.contains("items("));
     assertTrue(selector.contains("name"));
     assertTrue(selector.contains("nextPageToken"));
+    assertTrue(selector.endsWith(")"));
     assertEquals(25, selector.length());
     assertEquals(cursor, page.nextPageCursor());
     assertArrayEquals(bucketList.toArray(), Iterables.toArray(page.values(), Bucket.class));
@@ -679,13 +681,15 @@ public void testListBlobsWithSelectedFields() {
     assertEquals(BLOB_LIST_PREFIX.value(),
         capturedOptions.getValue().get(BLOB_LIST_PREFIX.rpcOption()));
     String selector = (String) capturedOptions.getValue().get(BLOB_LIST_FIELDS.rpcOption());
-    assertTrue(selector.contains("items"));
+    assertTrue(selector.contains("prefixes"));
+    assertTrue(selector.contains("items("));
     assertTrue(selector.contains("bucket"));
     assertTrue(selector.contains("name"));
     assertTrue(selector.contains("contentType"));
     assertTrue(selector.contains("md5Hash"));
     assertTrue(selector.contains("nextPageToken"));
-    assertEquals(52, selector.length());
+    assertTrue(selector.endsWith(")"));
+    assertEquals(61, selector.length());
     assertEquals(cursor, page.nextPageCursor());
     assertArrayEquals(blobList.toArray(), Iterables.toArray(page.values(), Blob.class));
   }
@@ -710,11 +714,13 @@ public void testListBlobsWithEmptyFields() {
     assertEquals(BLOB_LIST_PREFIX.value(),
         capturedOptions.getValue().get(BLOB_LIST_PREFIX.rpcOption()));
     String selector = (String) capturedOptions.getValue().get(BLOB_LIST_EMPTY_FIELDS.rpcOption());
-    assertTrue(selector.contains("items"));
+    assertTrue(selector.contains("prefixes"));
+    assertTrue(selector.contains("items("));
     assertTrue(selector.contains("bucket"));
     assertTrue(selector.contains("name"));
     assertTrue(selector.contains("nextPageToken"));
-    assertEquals(32, selector.length());
+    assertTrue(selector.endsWith(")"));
+    assertEquals(41, selector.length());
     assertEquals(cursor, page.nextPageCursor());
     assertArrayEquals(blobList.toArray(), Iterables.toArray(page.values(), Blob.class));
   }