Object metadata refers to the attribute description of an object, comprising both HTTP standard attributes (HTTP Header) and user-defined metadata (User Meta).

Set Custom Metadata

warning

By default, only the object owner has permission to set object metadata.

When configuring user-defined metadata, the key for user-defined metadata using English letters supports only lowercase letters and does not allow spaces or other special characters.

Setting Metadata Information During Standard Upload

You can set object metadata to identify the purpose or attributes of an object. The following code is used to set object metadata.

#include "TosClientV2.h"​
using namespace VolcengineTos;​
​
int main(void){​
    ​
    ​
    std::string region = "Your Region";​
    std::string accessKey = std::getenv("TOS_ACCESS_KEY");​
    std::string secretKey = std::getenv("TOS_SECRET_KEY");​
    ​
    std::string bucketName = "examplebucket";​
    ​
    std::string objectName = "exampledir/exampleobject.txt";​
​
   ​
    InitializeClient();​
    ​
    TosClientV2 client(region, accessKey, secretKey);​
​
  ​
    std::string data("Object data to be uploaded");​
    auto ss = std::make_shared<std::stringstream>(data);​
    PutObjectV2Input input(bucketName, objectName, ss);​
 ​
​
    input.setAcl(ACLType::PublicRead);​
​
    input.setStorageClass(StorageClassType::IA);​
​
    input.setMeta({{"self-test", "yes"}});​
​
    input.setContentType("application/json");​
​
    auto output = client.putObject(input);​
    if (!output.isSuccess()) {​
     ​
        std::cout << "PutObjectWithMetaData failed." << output.error().String() << std::endl;​
  ​
        CloseClient();​
        return -1;​
    }​
​
    std::cout << "PutObjectWithMetaData success. the object etag:" << output.result().getETag() << std::endl;​
​
   ​
    CloseClient();​
    return 0;​
}​

Setting Object Metadata During Multipart Upload

#include "TosClientV2.h"​
using namespace VolcengineTos;​
​
static int64_t getFileSize(const std::string& file)​
{​
    std::fstream f(file, std::ios::in | std::ios::binary);​
    f.seekg(0, f.end);​
    int64_t size = f.tellg();​
    f.close();​
    return size;​
}​
​
int main(void){​
​
​
    std::string region = "Your Region";​
    std::string accessKey = std::getenv("TOS_ACCESS_KEY");​
    std::string secretKey = std::getenv("TOS_SECRET_KEY");​
 ​
    std::string bucketName = "examplebucket";​
   ​
    std::string objectName = "exampledir/exampleobject.txt";​
​
  ​
    InitializeClient();​
 ​
    TosClientV2 client(region, accessKey, secretKey);​
​
​
    CreateMultipartUploadInput input(bucketName, objectName);​
 ​
    input.setAcl(ACLType::PublicRead);​
    input.setStorageClass(StorageClassType::IA);​
    input.setMeta({{"self-test", "yes"}});​
    auto upload = client.createMultipartUpload(input);​
    if (!upload.isSuccess()) {​
​
        std::cout << "createMultipartUpload failed." << upload.error().String() << std::endl;​
  ​
        CloseClient();​
        return -1;​
    }​
    std::cout << "createMultipartUpload success." << std::endl;​
​
​
    std::string fileToUpload = "yourLocalFilename";​
    int64_t partSize = 100 * 1024;​
    std::vector<UploadedPartV2> partResList;​
    auto fileSize = getFileSize(fileToUpload);​
    int partCount = static_cast<int>(fileSize / partSize);​
​
    if (fileSize % partSize != 0) {​
        partCount++;​
    }​
​
​
    auto uploadId = upload.result().getUploadId();​
    for (int i = 1; i <= partCount; i++) {​
        auto offset = partSize * (i - 1);​
        auto size = (partSize < fileSize - offset) ? partSize : (fileSize - offset);​
        std::shared_ptr<std::iostream> content = std::make_shared<std::fstream>(fileToUpload, std::ios::in|std::ios::binary);​
        content->seekg(offset, std::ios::beg);​
​
        UploadPartV2Input uploadPartInput(bucketName, objectName,uploadId, size,i,content);​
        auto uploadPartOutput = client.uploadPart(uploadPartInput);​
        if (!uploadPartOutput.isSuccess()) {​
            std::cout << "uploadPart failed." << upload.error().String() << std::endl;​
    ​
    CloseClient();​
            return -1;​
        }​
        UploadedPartV2 part(i, uploadPartOutput.result().getETag());​
        partResList.push_back(part);​
    }​
​
    ​
    CompleteMultipartUploadV2Input completeMultipartUploadInput(bucketName, objectName, uploadId, partResList);​
    auto com = client.completeMultipartUpload(completeMultipartUploadInput);​
    if (com.isSuccess()) {​
       ​
        std::cout << "CompleteMultipartUpload failed." << upload.error().String() << std::endl;​
  ​
        CloseClient();​
        return -1;​
    }​
    std::cout << "CompleteMultipartUpload success." << com.result().getRequestInfo().getRequestId() << std::endl;​
    CloseClient();​
    return 0;​
}​

Set object metadata via the setObjectMeta interface.

#include "TosClientV2.h"​
using namespace VolcengineTos;​
​
int main(void){​
   ​
  ​
    std::string region = "Your Region";​
    std::string accessKey = std::getenv("TOS_ACCESS_KEY");​
    std::string secretKey = std::getenv("TOS_SECRET_KEY");​
   ​
    std::string bucketName = "examplebucket";​
 ​
    std::string objectName = "exampledir/exampleobject.txt";​
​
    ​
    InitializeClient();​
    ​
    TosClientV2 client(region, accessKey, secretKey);​
​
    SetObjectMetaInput input(bucketName,objectName);​
​
    input.setMeta({{"self-test", "yes"}});​
    auto output = client.setObjectMeta(input);​
    if (!output.isSuccess()) {​
   ​
        std::cout << "SetObjectMeta failed." << output.error().String() << std::endl;​
​
        CloseClient();​
        return -1;​
    }​
​
    std::cout << "SetObjectMeta success." << std::endl;​
​
​
    CloseClient();​
    return 0;​
}​