Torch Object Storage
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Torch Object StorageSDK ReferenceC++Object InterfaceList ObjectsListing Objects (C++ SDK)
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Listing Objects (C++ SDK)
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This article describes how to use ListObject to enumerate all objects within a specified bucket, files with a designated prefix, and files and subdirectories within a specified directory.
Precautions
- The ListObjects interface has been revised to ListObjectsType2. It is strongly recommended that developers use ListObjectsType2. To ensure backward compatibility, TOS continues to support the ListObjects interface.
- To use List Objects V2, you must have the tos:ListBucket permission. For specific instructions, refer to the IAM Policy Overview.
Parameter Description
Parameters | Description |
prefix | The prefix of the current query results. |
delimiter | Character used to group object names. |
marker | Starting position of the enumerated object. Configure the system to return a list of objects sorted alphabetically, starting after the specified value. This is typically the value of nextMarker returned by the previous request. |
maxKeys | Returns the maximum number of objects to enumerate. The default value is 1000. Value: greater than 0 and less than or equal to 1000. |
encodingType | Encode the returned content and specify the type of encoding. Default value: None |
Sample Code
Brief Enumeration
The following code is used to list up to 10 objects in the bucket examplebucket.
#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";
InitializeClient();
TosClientV2 client(region, accessKey, secretKey);
ListObjectsV2Input input(bucketName);
input.setMaxKeys(10);
auto output = client.listObjects(input);
if (!output.isSuccess()) {
std::cout << "ListObjects failed." << output.error().String() << std::endl;
CloseClient();
return -1;
}
std::cout << "ListObjects success." << std::endl;
for (const auto& object : output.result().getContents()) {
std::cout << "object"
<< ",name:" << object.getKey() << ",size:" << object.getSize()
<< ",lastmodify time:" << object.getStringFormatLastModified()
<< ",storage class:" << object.getStringFormatStorageClass() << std::endl;
}
CloseClient();
return 0;
}
Paginated Listing
The following code is used to list up to 200 objects in the examplebucket bucket. By setting maxKeys, you can specify the maximum number of objects returned in a single request. By setting marker to the nextMarker returned from the first listing, you can continue listing objects.
#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";
InitializeClient();
TosClientV2 client(region, accessKey, secretKey);
ListObjectsV2Input input(bucketName);
input.setMaxKeys(100);
auto output = client.listObjects(input);
if (!output.isSuccess()) {
std::cout << "ListObjects failed." << output.error().String() << std::endl;
CloseClient();
return -1;
}
std::cout << "ListObjects success." << std::endl;
for (const auto& object : output.result().getContents()) {
std::cout << "object"<<
",name:" << object.getKey() <<
",size:" << object.getSize() <<
",lastmodify time:" << object.getStringFormatLastModified() <<
",storage class:" << object.getStringFormatStorageClass() << std::endl;
}
if(output.result().isTruncated()){
input.setMarker(output.result().getNextMarker());
auto output1 = client.listObjects(input);
if (!output1.isSuccess()) {
std::cout << "ListObjects failed." << output.error().String() << std::endl;
CloseClient();
return -1;
}
std::cout << "ListObjects success." << std::endl;
for (const auto& object : output1.result().getContents()) {
std::cout << "object"<<
",name:" << object.getKey() <<
",size:" << object.getSize() <<
",lastmodify time:" << object.getStringFormatLastModified() <<
",storage class:" << object.getStringFormatStorageClass() << std::endl;
}
}
CloseClient();
return 0;
}
List all objects with the specified prefix
The following code is used to list all objects with the specified prefix in the bucket examplebucket.
#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 prefix = "yourkeyPrefix";
InitializeClient();
TosClientV2 client(region, accessKey, secretKey);
ListObjectsV2Input input(bucketName);
input.setPrefix(prefix);
bool isTruncated = true;
std::string nextMarker = "";
while(isTruncated){
input.setMarker(nextMarker);
auto output = client.listObjects(input);
if (!output.isSuccess()) {
std::cout << "ListObjects failed." << output.error().String() << std::endl;
CloseClient();
return -1;
}
nextMarker = output.result().getNextMarker();
isTruncated = output.result().isTruncated();
std::cout << "ListObjects success." << std::endl;
for (const auto& object : output.result().getContents()) {
std::cout << "object"<<
",name:" << object.getKey() <<
",size:" << object.getSize() <<
",lastmodify time:" << object.getStringFormatLastModified() <<
",storage class:" << object.getStringFormatStorageClass() << std::endl;
}
}
CloseClient();
return 0;
}
Enumerate all objects
The following code is used to list all objects in the examplebucket bucket.
#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 prefix = "yourkeyPrefix";
InitializeClient();
TosClientV2 client(region, accessKey, secretKey);
ListObjectsV2Input input(bucketName);
input.setMaxKeys(100);
bool isTruncated = true;
std::string nextMarker = "";
while(isTruncated){
input.setMarker(nextMarker);
auto output = client.listObjects(input);
if (!output.isSuccess()) {
std::cout << "ListObjects failed." << output.error().String() << std::endl;
CloseClient();
return -1;
}
nextMarker = output.result().getNextMarker();
isTruncated = output.result().isTruncated();
std::cout << "ListObjects success." << std::endl;
for (const auto& object : output.result().getContents()) {
std::cout << "object"<<
",name:" << object.getKey() <<
",size:" << object.getSize() <<
",lastmodify time:" << object.getStringFormatLastModified() <<
",storage class:" << object.getStringFormatStorageClass() << std::endl;
}
}
CloseClient();
return 0;
}
Enumerate the files and subdirectories within the specified directory.
TOS is based solely on the concept of objects; it is possible to create an object with a size of zero and a name containing a slash./The object at the end simulates the functionality of a directory.
The functionality of a directory can be simulated using the delimiter and prefix parameters:
- First, set delimiter to/By simultaneously setting prefix to empty, the objects and subdirectory information in the root directory can be returned.
- Set the delimiter again to/When prefix is simultaneously set as the subdirectory (subfiledir), objects and subdirectories within it can be returned.
The following code enumerates the objects and subdirectories in the root directory.
#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";
InitializeClient();
TosClientV2 client(region, accessKey, secretKey);
ListObjectsV2Input input(bucketName);
input.setDelimiter("/");
input.setMaxKeys(10);
auto output = client.listObjects(input);
if (!output.isSuccess()) {
std::cout << "ListObjects failed." << output.error().String() << std::endl;
CloseClient();
return -1;
}
std::cout << "ListObjects success." << std::endl;
for (const auto& object : output.result().getContents()) {
std::cout << "object"<<
",name:" << object.getKey() <<
",size:" << object.getSize() <<
",lastmodify time:" << object.getStringFormatLastModified() <<
",storage class:" << object.getStringFormatStorageClass() << std::endl;
}
for (const auto& prefix : output.result().getCommonPrefixes()) {
std::cout << "Sub Dir:"<< prefix.getPrefix() << std::endl;
}
CloseClient();
return 0;
}
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Last updated: 2025.09.25 14:22:47
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