Use GetObjectAttributes with an AWS SDK or CLI - AWS SDK Code Examples

There are more AWS SDK examples available in the AWS Doc SDK Examples GitHub repo.

Use GetObjectAttributes with an AWS SDK or CLI

The following code examples show how to use GetObjectAttributes.

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C++
SDK for C++
Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

// ! Routine which retrieves the hash value of an object stored in an S3 bucket. /*! \param bucket: The name of the S3 bucket where the object is stored. \param key: The unique identifier (key) of the object within the S3 bucket. \param hashMethod: The hashing algorithm used to calculate the hash value of the object. \param[out] hashData: The retrieved hash. \param[out] partHashes: The part hashes if available. \param client: The S3 client instance used to retrieve the object. \return bool: Function succeeded. */ bool AwsDoc::S3::retrieveObjectHash(const Aws::String &bucket, const Aws::String &key, AwsDoc::S3::HASH_METHOD hashMethod, Aws::String &hashData, std::vector<Aws::String> *partHashes, const Aws::S3::S3Client &client) { Aws::S3::Model::GetObjectAttributesRequest request; request.SetBucket(bucket); request.SetKey(key); if (hashMethod == MD5) { Aws::Vector<Aws::S3::Model::ObjectAttributes> attributes; attributes.push_back(Aws::S3::Model::ObjectAttributes::ETag); request.SetObjectAttributes(attributes); Aws::S3::Model::GetObjectAttributesOutcome outcome = client.GetObjectAttributes( request); if (outcome.IsSuccess()) { const Aws::S3::Model::GetObjectAttributesResult &result = outcome.GetResult(); hashData = result.GetETag(); } else { std::cerr << "Error retrieving object etag attributes." << outcome.GetError().GetMessage() << std::endl; return false; } } else { // hashMethod != MD5 Aws::Vector<Aws::S3::Model::ObjectAttributes> attributes; attributes.push_back(Aws::S3::Model::ObjectAttributes::Checksum); request.SetObjectAttributes(attributes); Aws::S3::Model::GetObjectAttributesOutcome outcome = client.GetObjectAttributes( request); if (outcome.IsSuccess()) { const Aws::S3::Model::GetObjectAttributesResult &result = outcome.GetResult(); switch (hashMethod) { case AwsDoc::S3::DEFAULT: // NOLINT(*-branch-clone) break; // Default is not supported. #pragma clang diagnostic push #pragma ide diagnostic ignored "UnreachableCode" case AwsDoc::S3::MD5: break; // MD5 is not supported. #pragma clang diagnostic pop case AwsDoc::S3::SHA1: hashData = result.GetChecksum().GetChecksumSHA1(); break; case AwsDoc::S3::SHA256: hashData = result.GetChecksum().GetChecksumSHA256(); break; case AwsDoc::S3::CRC32: hashData = result.GetChecksum().GetChecksumCRC32(); break; case AwsDoc::S3::CRC32C: hashData = result.GetChecksum().GetChecksumCRC32C(); break; default: std::cerr << "Unknown hash method." << std::endl; return false; } } else { std::cerr << "Error retrieving object checksum attributes." << outcome.GetError().GetMessage() << std::endl; return false; } if (nullptr != partHashes) { attributes.clear(); attributes.push_back(Aws::S3::Model::ObjectAttributes::ObjectParts); request.SetObjectAttributes(attributes); outcome = client.GetObjectAttributes(request); if (outcome.IsSuccess()) { const Aws::S3::Model::GetObjectAttributesResult &result = outcome.GetResult(); const Aws::Vector<Aws::S3::Model::ObjectPart> parts = result.GetObjectParts().GetParts(); for (const Aws::S3::Model::ObjectPart &part: parts) { switch (hashMethod) { case AwsDoc::S3::DEFAULT: // Default is not supported. NOLINT(*-branch-clone) break; case AwsDoc::S3::MD5: // MD5 is not supported. break; case AwsDoc::S3::SHA1: partHashes->push_back(part.GetChecksumSHA1()); break; case AwsDoc::S3::SHA256: partHashes->push_back(part.GetChecksumSHA256()); break; case AwsDoc::S3::CRC32: partHashes->push_back(part.GetChecksumCRC32()); break; case AwsDoc::S3::CRC32C: partHashes->push_back(part.GetChecksumCRC32C()); break; default: std::cerr << "Unknown hash method." << std::endl; return false; } } } else { std::cerr << "Error retrieving object attributes for object parts." << outcome.GetError().GetMessage() << std::endl; return false; } } } return true; }
CLI
AWS CLI

To retrieves metadata from an object without returning the object itself

The following get-object-attributes example retrieves metadata from the object doc1.rtf.

aws s3api get-object-attributes \ --bucket my-bucket \ --key doc1.rtf \ --object-attributes "StorageClass" "ETag" "ObjectSize"

Output:

{ "LastModified": "2022-03-15T19:37:31+00:00", "VersionId": "IuCPjXTDzHNfldAuitVBIKJpF2p1fg4P", "ETag": "b662d79adeb7c8d787ea7eafb9ef6207", "StorageClass": "STANDARD", "ObjectSize": 405 }

For more information, see GetObjectAttributes in the Amazon S3 API Reference.