You can obtain information about a bucket using HeadBucket, and determine whether the bucket exists based on the HTTP response code. This article describes how to obtain bucket metadata and determine whether a bucket exists.

Notes

Before retrieving bucket metadata, you must ensure that your account already has the tos:HeadBucket permission. For detailed instructions, please refer to the Permission Configuration Guide.

If the bucket does not exist, this interface will return a 404 error. This interface is also commonly used to determine whether the bucket exists.

Sample Code

Determine whether the bucket exists

The following code is used to check whether the bucket exists.

using System;​
using TOS;​
using TOS.Error;​
using TOS.Model;​
​
namespace ConsoleApp​
{​
    internal class Program​
    {​
        private static void Main(string[] args)​
        {​
            var ak = Environment.GetEnvironmentVariable("TOS_ACCESS_KEY");​
            var sk = Environment.GetEnvironmentVariable("TOS_SECRET_KEY");​
            var endpoint = "https://tos-cn-beijing.volces.com";​
            var region = "cn-beijing";​
            var bucketName = "*** Provide your bucket name ***";​
​
            var client = TosClientBuilder.Builder().SetAk(ak).SetSk(sk).SetEndpoint(endpoint).SetRegion(region).Build();​
​
            try​
            {​
                var headBucketInput = new HeadBucketInput()​
                {​
                    Bucket = bucketName,​
                };​
                var headBucketOutput = client.HeadBucket(headBucketInput);​
                Console.WriteLine("Head bucket succeeded, request id {0} ", headBucketOutput.RequestID);​
                Console.WriteLine("Head bucket succeeded, status code {0} ", headBucketOutput.StatusCode);​
            }​
            catch (TosServerException ex)​
            {​
                if (ex.StatusCode == 404)​
                {​
                    Console.WriteLine("Bucket not found");​
                }​
                Console.WriteLine("Head bucket failed, request id {0}", ex.RequestID);​
                Console.WriteLine("Head bucket failed, status code {0}", ex.StatusCode);​
                Console.WriteLine("Head bucket failed, response error code {0}", ex.Code);​
                Console.WriteLine("Head bucket failed, response error message {0}", ex.Message);​
            }​
            catch (TosClientException ex)​
            {​
                Console.WriteLine("Head bucket failed, error message {0}", ex.Message);​
            }​
            catch (Exception ex)​
            {​
                Console.WriteLine("Head bucket failed, {0}", ex.Message);​
            }​
        }​
    }​
}​

Retrieve Bucket Metadata Information

The following code is used to retrieve bucket metadata information.

using System;​
using TOS;​
using TOS.Error;​
using TOS.Model;​
​
namespace ConsoleApp​
{​
    internal class Program​
    {​
        private static void Main(string[] args)​
        {​
            var ak = Environment.GetEnvironmentVariable("TOS_ACCESS_KEY");​
            var sk = Environment.GetEnvironmentVariable("TOS_SECRET_KEY");​
            var endpoint = "https://tos-cn-beijing.volces.com";​
            var region = "cn-beijing";​
            var bucketName = "*** Provide your bucket name ***";​
​
            var client = TosClientBuilder.Builder().SetAk(ak).SetSk(sk).SetEndpoint(endpoint).SetRegion(region).Build();​
​
            try​
            {​
                var headBucketInput = new HeadBucketInput()​
                {​
                    Bucket = bucketName,​
                };​
                var headBucketOutput = client.HeadBucket(headBucketInput);​
                Console.WriteLine("Head bucket succeeded, request id {0} ", headBucketOutput.RequestID);​
                Console.WriteLine("Head bucket succeeded, status code {0} ", headBucketOutput.StatusCode);​
                Console.WriteLine("Bucket Region {0}", headBucketOutput.Region);​
                Console.WriteLine("Bucket Storage Class {0}", headBucketOutput.StorageClass);​
                Console.WriteLine("Bucket Az Redundancy {0}", headBucketOutput.AzRedundancy);​
            }​
            catch (TosServerException ex)​
            {​
                if (ex.StatusCode == 404)​
                {​
                    Console.WriteLine("Bucket not found");​
                }​
                Console.WriteLine("Head bucket failed, request id {0}", ex.RequestID);​
                Console.WriteLine("Head bucket failed, status code {0}", ex.StatusCode);​
                Console.WriteLine("Head bucket failed, response error code {0}", ex.Code);​
                Console.WriteLine("Head bucket failed, response error message {0}", ex.Message);​
            }​
            catch (TosClientException ex)​
            {​
                Console.WriteLine("Head bucket failed, error message {0}", ex.Message);​
            }​
            catch (Exception ex)​
            {​
                Console.WriteLine("Head bucket failed, {0}", ex.Message);​
            }​
        }​
    }​
}​