Listing objects in a versioning-enabled bucket - Amazon Simple Storage Service

Listing objects in a versioning-enabled bucket

This section provides examples of listing object versions from a versioning-enabled bucket. Amazon S3 stores object version information in the versions subresource that is associated with the bucket. For more information, see Bucket configuration options.

Follow these steps to use the Amazon S3 console to see the different versions of an object.

To see multiple versions of an object

  1. Sign in to the AWS Management Console and open the Amazon S3 console at https://console.aws.amazon.com/s3/.

  2. In the Buckets list, choose the name of the bucket that contains the object.

  3. To see a list of the versions of the objects in the bucket, choose the List versions switch.

    For each object version, the console shows a unique version ID, the date and time the object version was created, and other properties. (Objects stored in your bucket before you set the versioning state have a version ID of null.)

    To list the objects without the versions, choose the List versions switch.

You also can view, download, and delete object versions in the object overview pane on the console. For more information, see Viewing an object overview in the Amazon S3 console.

Important

You can undelete an object only if it was deleted as the latest (current) version. You can't undelete a previous version of an object that was deleted. For more information, see Using versioning in S3 buckets.

The examples in this section show how to retrieve an object listing from a versioning-enabled bucket. Each request returns up to 1,000 versions, unless you specify a lower number. If the bucket contains more versions than this limit, you send a series of requests to retrieve the list of all versions. This process of returning results in "pages" is called pagination.

To show how pagination works, the examples limit each response to two object versions. After retrieving the first page of results, each example checks to determine whether the version list was truncated. If it was, the example continues retrieving pages until all versions have been retrieved.

Note

The following examples also work with a bucket that isn't versioning-enabled, or for objects that don't have individual versions. In those cases, Amazon S3 returns the object listing with a version ID of null.

For information about using other AWS SDKs, see the AWS Developer Center.

Java

For instructions on creating and testing a working sample, see Testing the Amazon S3 Java Code Examples.

import com.amazonaws.AmazonServiceException; import com.amazonaws.SdkClientException; import com.amazonaws.auth.profile.ProfileCredentialsProvider; import com.amazonaws.regions.Regions; import com.amazonaws.services.s3.AmazonS3; import com.amazonaws.services.s3.AmazonS3ClientBuilder; import com.amazonaws.services.s3.model.ListVersionsRequest; import com.amazonaws.services.s3.model.S3VersionSummary; import com.amazonaws.services.s3.model.VersionListing; public class ListKeysVersioningEnabledBucket { public static void main(String[] args) { Regions clientRegion = Regions.DEFAULT_REGION; String bucketName = "*** Bucket name ***"; try { AmazonS3 s3Client = AmazonS3ClientBuilder.standard() .withCredentials(new ProfileCredentialsProvider()) .withRegion(clientRegion) .build(); // Retrieve the list of versions. If the bucket contains more versions // than the specified maximum number of results, Amazon S3 returns // one page of results per request. ListVersionsRequest request = new ListVersionsRequest() .withBucketName(bucketName) .withMaxResults(2); VersionListing versionListing = s3Client.listVersions(request); int numVersions = 0, numPages = 0; while (true) { numPages++; for (S3VersionSummary objectSummary : versionListing.getVersionSummaries()) { System.out.printf("Retrieved object %s, version %s\n", objectSummary.getKey(), objectSummary.getVersionId()); numVersions++; } // Check whether there are more pages of versions to retrieve. If // there are, retrieve them. Otherwise, exit the loop. if (versionListing.isTruncated()) { versionListing = s3Client.listNextBatchOfVersions(versionListing); } else { break; } } System.out.println(numVersions + " object versions retrieved in " + numPages + " pages"); } catch (AmazonServiceException e) { // The call was transmitted successfully, but Amazon S3 couldn't process // it, so it returned an error response. e.printStackTrace(); } catch (SdkClientException e) { // Amazon S3 couldn't be contacted for a response, or the client // couldn't parse the response from Amazon S3. e.printStackTrace(); } } }
.NET

For information about how to create and test a working sample, see Running the Amazon S3 .NET Code Examples.

using Amazon; using Amazon.S3; using Amazon.S3.Model; using System; using System.Threading.Tasks; namespace Amazon.DocSamples.S3 { class ListObjectsVersioningEnabledBucketTest { static string bucketName = "*** bucket name ***"; // Specify your bucket region (an example region is shown). private static readonly RegionEndpoint bucketRegion = RegionEndpoint.USWest2; private static IAmazonS3 s3Client; public static void Main(string[] args) { s3Client = new AmazonS3Client(bucketRegion); GetObjectListWithAllVersionsAsync().Wait(); } static async Task GetObjectListWithAllVersionsAsync() { try { ListVersionsRequest request = new ListVersionsRequest() { BucketName = bucketName, // You can optionally specify key name prefix in the request // if you want list of object versions of a specific object. // For this example we limit response to return list of 2 versions. MaxKeys = 2 }; do { ListVersionsResponse response = await s3Client.ListVersionsAsync(request); // Process response. foreach (S3ObjectVersion entry in response.Versions) { Console.WriteLine("key = {0} size = {1}", entry.Key, entry.Size); } // If response is truncated, set the marker to get the next // set of keys. if (response.IsTruncated) { request.KeyMarker = response.NextKeyMarker; request.VersionIdMarker = response.NextVersionIdMarker; } else { request = null; } } while (request != null); } catch (AmazonS3Exception e) { Console.WriteLine("Error encountered on server. Message:'{0}' when writing an object", e.Message); } catch (Exception e) { Console.WriteLine("Unknown encountered on server. Message:'{0}' when writing an object", e.Message); } } } }

Example — Listing all object versions in a bucket

To list all the versions of all the objects in a bucket, you use the versions subresource in a GET Bucket request. Amazon S3 can retrieve a maximum of 1,000 objects, and each object version counts fully as an object. Therefore, if a bucket contains two keys (for example, photo.gif and picture.jpg), and the first key has 990 versions and the second key has 400 versions, a single request would retrieve all 990 versions of photo.gif and only the most recent 10 versions of picture.jpg.

Amazon S3 returns object versions in the order in which they were stored, with the most recently stored returned first.

In a GET Bucket request, include the versions subresource.

GET /?versions HTTP/1.1 Host: bucketName.s3.amazonaws.com Date: Wed, 28 Oct 2009 22:32:00 +0000 Authorization: AWS AKIAIOSFODNN7EXAMPLE:0RQf4/cRonhpaBX5sCYVf1bNRuU=

Example — Retrieving all versions of a key

To retrieve a subset of object versions, you use the request parameters for GET Bucket. For more information, see GET Bucket.

  1. Set the prefix parameter to the key of the object that you want to retrieve.

  2. Send a GET Bucket request using the versions subresource and prefix.

    GET /?versions&prefix=objectName HTTP/1.1

Example — Retrieving objects using a prefix

The following example retrieves objects whose key is or begins with myObject.

GET /?versions&prefix=myObject HTTP/1.1 Host: bucket.s3.amazonaws.com Date: Wed, 28 Oct 2009 22:32:00 GMT Authorization: AWS AKIAIOSFODNN7EXAMPLE:0RQf4/cRonhpaBX5sCYVf1bNRuU=

You can use the other request parameters to retrieve a subset of all versions of the object. For more information, see GET Bucket in the Amazon Simple Storage Service API Reference.

Example — Retrieving a listing of additional objects if the response is truncated

If the number of objects that could be returned in a GET request exceeds the value of max-keys, the response contains <isTruncated>true</isTruncated>, and includes the first key (in NextKeyMarker) and the first version ID (in NextVersionIdMarker) that satisfy the request, but were not returned. You use those returned values as the starting position in a subsequent request to retrieve the additional objects that satisfy the GET request.

Use the following process to retrieve additional objects that satisfy the original GET Bucket versions request from a bucket. For more information about key-marker, version-id-marker, NextKeyMarker, and NextVersionIdMarker, see GET Bucket. in the Amazon Simple Storage Service API Reference.

The following are additional responses that satisfy the original GET request:

  • Set the value of key-marker to the key returned in NextKeyMarker in the previous response.

  • Set the value of version-id-marker to the version ID returned in NextVersionIdMarker in the previous response.

  • Send a GET Bucket versions request using key-marker and version-id-marker.

Example — Retrieving objects starting with a specified key and version ID

GET /?versions&key-marker=myObject&version-id-marker=298459348571 HTTP/1.1 Host: bucket.s3.amazonaws.com Date: Wed, 28 Oct 2009 22:32:00 GMT Authorization: AWS AKIAIOSFODNN7EXAMPLE:0RQf4/cRonhpaBX5sCYVf1bNRuU=