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Object Storage Service:Query object metadata by using OSS SDK for .NET

Last Updated:Feb 01, 2024

By default, when you call the HeadObject operation on an Object Storage Service (OSS) object in a versioning-enabled bucket, the metadata of only the current version of the object is returned.

Note

If the current version of the object is a delete marker, OSS returns 404 Not Found. If you specify a version ID in the request, OSS returns the metadata of the specified version of the object.

Usage notes

  • In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions and endpoints.

  • In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Initialization.

  • To query object metadata, you must have the oss:GetObject permission. For more information, see Attach a custom policy to a RAM user.

Examples

The following sample code provides an example on how to query the metadata of an object:

using Aliyun.OSS;
using Aliyun.OSS.Common;
// Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. 
var endpoint = "yourEndpoint";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
var accessKeyId = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_ID");
var accessKeySecret = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_SECRET");
// Specify the name of the bucket. Example: examplebucket. 
var bucketName = "examplebucket";
// Specify the full path of the object. Do not include the bucket name in the full path. Example: exampledir/exampleobject.txt. 
var objectName = "exampledir/exampleobject.txt";
var versionid = "yourArchiveObjectVersionid";
// Create an OSSClient instance. 
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    // Query the object metadata. 
    var request = new GetObjectMetadataRequest(bucketName, objectName)
    {
        // Query the metadata of the specified version of the object. 
        VersionId = versionid
    };

    // Query all metadata of the specified version of the object. 
    var oldMeta = client.GetObjectMetadata(request);

    // Query part of the metadata of the specified version of the object. 
    var meta = client.GetSimplifiedObjectMetadata(request);
}
catch (Exception ex)
{
    Console.WriteLine("Put object failed, {0}", ex.Message);
}

References

For more information about the API operations that you can call to query object metadata, see GetObjectMeta and HeadObject.