Object Storage Service:Check whether a file exists (C# SDK V1)

Prerequisites

Before you begin, ensure that you have:

• An OSS bucket in the target region

• The oss:GetObject permission on the target object. For details, see Attach a custom policy to a RAM user

• The OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables set with valid credentials

Usage notes

• The sample code uses the public endpoint for the China (Hangzhou) region. To access OSS from another Alibaba Cloud service in the same region, use the internal endpoint instead. See Regions and endpoints.

• To create an OSSClient instance using a custom domain name or Security Token Service (STS), see Initialization.

Check whether an object exists

using Aliyun.OSS;
using Aliyun.OSS.Common;

// Set the endpoint for the region where your bucket is located.
// Example: https://oss-cn-hangzhou.aliyuncs.com for China (Hangzhou).
var endpoint = "yourEndpoint";

// Load credentials from environment variables.
var accessKeyId = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_ID");
var accessKeySecret = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_SECRET");

// Specify the bucket name.
var bucketName = "examplebucket";

// Specify the full object path, excluding the bucket name.
var objectName = "exampledir/exampleobject.txt";

// Specify the region ID of the bucket.
const string region = "cn-hangzhou";

// Create a ClientConfiguration instance and enable Signature V4.
var conf = new ClientConfiguration();
conf.SignatureVersion = SignatureVersion.V4;

// Create an OssClient instance.
var client = new OssClient(endpoint, accessKeyId, accessKeySecret, conf);

try
{
    bool exist = client.DoesObjectExist(bucketName, objectName);
    Console.WriteLine("Object exists: " + exist);
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error code: {0}; Error info: {1}. \nRequestId:{2}\tHostId:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

Note: For the complete sample, see GitHub.