AWS SDK Version 4 for .NET
API Reference

AWS services or capabilities described in AWS Documentation may vary by region/location. Click Getting Started with Amazon AWS to see specific differences applicable to the China (Beijing) Region.

Container for the parameters to the GetObjectMetadata operation. The HEAD operation retrieves metadata from an object without returning the object itself. This operation is useful if you're interested only in an object's metadata.

A HEAD request has the same options as a GET operation on an object. The response is identical to the GET response except that there is no response body. Because of this, if the HEAD request generates an error, it returns a generic code, such as 400 Bad Request, 403 Forbidden, 404 Not Found, 405 Method Not Allowed, 412 Precondition Failed, or 304 Not Modified. It's not possible to retrieve the exact exception of these error codes.

Request headers are limited to 8 KB in size. For more information, see Common Request Headers.

Permissions

  • General purpose bucket permissions - To use HEAD, you must have the s3:GetObject permission. You need the relevant read object (or version) permission for this operation. For more information, see Actions, resources, and condition keys for Amazon S3 in the Amazon S3 User Guide. For more information about the permissions to S3 API operations by S3 resource types, see Required permissions for Amazon S3 API operations in the Amazon S3 User Guide.

    If the object you request doesn't exist, the error that Amazon S3 returns depends on whether you also have the s3:ListBucket permission.

    • If you have the s3:ListBucket permission on the bucket, Amazon S3 returns an HTTP status code 404 Not Found error.

    • If you don’t have the s3:ListBucket permission, Amazon S3 returns an HTTP status code 403 Forbidden error.

  • Directory bucket permissions - To grant access to this API operation on a directory bucket, we recommend that you use the CreateSession API operation for session-based authorization. Specifically, you grant the s3express:CreateSession permission to the directory bucket in a bucket policy or an IAM identity-based policy. Then, you make the CreateSession API call on the bucket to obtain a session token. With the session token in your request header, you can make API requests to this operation. After the session token expires, you make another CreateSession API call to generate a new session token for use. Amazon Web Services CLI or SDKs create session and refresh the session token automatically to avoid service interruptions when a session expires. For more information about authorization, see CreateSession.

    If you enable x-amz-checksum-mode in the request and the object is encrypted with Amazon Web Services Key Management Service (Amazon Web Services KMS), you must also have the kms:GenerateDataKey and kms:Decrypt permissions in IAM identity-based policies and KMS key policies for the KMS key to retrieve the checksum of the object.

Encryption

Encryption request headers, like x-amz-server-side-encryption, should not be sent for HEAD requests if your object uses server-side encryption with Key Management Service (KMS) keys (SSE-KMS), dual-layer server-side encryption with Amazon Web Services KMS keys (DSSE-KMS), or server-side encryption with Amazon S3 managed encryption keys (SSE-S3). The x-amz-server-side-encryption header is used when you PUT an object to S3 and want to specify the encryption method. If you include this header in a HEAD request for an object that uses these types of keys, you’ll get an HTTP 400 Bad Request error. It's because the encryption method can't be changed when you retrieve the object.

If you encrypt an object by using server-side encryption with customer-provided encryption keys (SSE-C) when you store the object in Amazon S3, then when you retrieve the metadata from the object, you must use the following headers to provide the encryption key for the server to be able to retrieve the object's metadata. The headers are:

  • x-amz-server-side-encryption-customer-algorithm

  • x-amz-server-side-encryption-customer-key

  • x-amz-server-side-encryption-customer-key-MD5

For more information about SSE-C, see Server-Side Encryption (Using Customer-Provided Encryption Keys) in the Amazon S3 User Guide.

Directory bucket - For directory buckets, there are only two supported options for server-side encryption: SSE-S3 and SSE-KMS. SSE-C isn't supported. For more information, see Protecting data with server-side encryption in the Amazon S3 User Guide.

Versioning

  • If the current version of the object is a delete marker, Amazon S3 behaves as if the object was deleted and includes x-amz-delete-marker: true in the response.

  • If the specified version is a delete marker, the response returns a 405 Method Not Allowed error and the Last-Modified: timestamp response header.

  • Directory buckets - Delete marker is not supported for directory buckets.

  • Directory buckets - S3 Versioning isn't enabled and supported for directory buckets. For this API operation, only the null value of the version ID is supported by directory buckets. You can only specify null to the versionId query parameter in the request.

HTTP Host header syntax

Directory buckets - The HTTP Host header syntax is Bucket-name.s3express-zone-id.region-code.amazonaws.com.

For directory buckets, you must make requests for this API operation to the Zonal endpoint. These endpoints support virtual-hosted-style requests in the format https://amzn-s3-demo-bucket.s3express-zone-id.region-code.amazonaws.com/key-name. Path-style requests are not supported. For more information about endpoints in Availability Zones, see Regional and Zonal endpoints for directory buckets in Availability Zones in the Amazon S3 User Guide. For more information about endpoints in Local Zones, see Concepts for directory buckets in Local Zones in the Amazon S3 User Guide.

The following actions are related to HeadObject:

Inheritance Hierarchy

System.Object
  Amazon.Runtime.AmazonWebServiceRequest
    Amazon.S3.Model.GetObjectMetadataRequest

Namespace: Amazon.S3.Model
Assembly: AWSSDK.S3.dll
Version: 3.x.y.z

Syntax

C# 
public class GetObjectMetadataRequest : AmazonWebServiceRequest
         IAmazonWebServiceRequest

The GetObjectMetadataRequest type exposes the following members

Constructors

NameDescription
Public Method GetObjectMetadataRequest()

Properties

NameTypeDescription
Public Property BucketName System.String

Gets and sets the property BucketName.

The name of the bucket that contains the object.

Directory buckets - When you use this operation with a directory bucket, you must use virtual-hosted-style requests in the format Bucket-name.s3express-zone-id.region-code.amazonaws.com. Path-style requests are not supported. Directory bucket names must be unique in the chosen Zone (Availability Zone or Local Zone). Bucket names must follow the format bucket-base-name--zone-id--x-s3 (for example, amzn-s3-demo-bucket--usw2-az1--x-s3). For information about bucket naming restrictions, see Directory bucket naming rules in the Amazon S3 User Guide.

Access points - When you use this action with an access point for general purpose buckets, you must provide the alias of the access point in place of the bucket name or specify the access point ARN. When you use this action with an access point for directory buckets, you must provide the access point name in place of the bucket name. When using the access point ARN, you must direct requests to the access point hostname. The access point hostname takes the form AccessPointName-AccountId.s3-accesspoint.Region.amazonaws.com. When using this action with an access point through the Amazon Web Services SDKs, you provide the access point ARN in place of the bucket name. For more information about access point ARNs, see Using access points in the Amazon S3 User Guide.

Object Lambda access points are not supported by directory buckets.

S3 on Outposts - When you use this action with S3 on Outposts, you must direct requests to the S3 on Outposts hostname. The S3 on Outposts hostname takes the form AccessPointName-AccountId.outpostID.s3-outposts.Region.amazonaws.com. When you use this action with S3 on Outposts, the destination bucket must be the Outposts access point ARN or the access point alias. For more information about S3 on Outposts, see What is S3 on Outposts? in the Amazon S3 User Guide.

Public Property ChecksumMode Amazon.S3.ChecksumMode

Gets and sets the property ChecksumMode.

To retrieve the checksum, this parameter must be enabled.

General purpose buckets - If you enable checksum mode and the object is uploaded with a checksum and encrypted with an Key Management Service (KMS) key, you must have permission to use the kms:Decrypt action to retrieve the checksum.

Directory buckets - If you enable ChecksumMode and the object is encrypted with Amazon Web Services Key Management Service (Amazon Web Services KMS), you must also have the kms:GenerateDataKey and kms:Decrypt permissions in IAM identity-based policies and KMS key policies for the KMS key to retrieve the checksum of the object.

Public Property EtagToMatch System.String

Gets and sets the property EtagToMatch.

Return the object only if its entity tag (ETag) is the same as the one specified; otherwise, return a 412 (precondition failed) error.

If both of the If-Match and If-Unmodified-Since headers are present in the request as follows:

  • If-Match condition evaluates to true, and;

  • If-Unmodified-Since condition evaluates to false;

Then Amazon S3 returns 200 OK and the data requested.

For more information about conditional requests, see RFC 7232.

Public Property EtagToNotMatch System.String

Gets and sets the property EtagToNotMatch.

Return the object only if its entity tag (ETag) is different from the one specified; otherwise, return a 304 (not modified) error.

If both of the If-None-Match and If-Modified-Since headers are present in the request as follows:

  • If-None-Match condition evaluates to false, and;

  • If-Modified-Since condition evaluates to true;

Then Amazon S3 returns the 304 Not Modified response code.

For more information about conditional requests, see RFC 7232.

Public Property ExpectedBucketOwner System.String

Gets and sets the property ExpectedBucketOwner.

The account ID of the expected bucket owner. If the account ID that you provide does not match the actual owner of the bucket, the request fails with the HTTP status code 403 Forbidden (access denied).

Public Property Key System.String

Gets and sets the property Key.

The object key.

Public Property ModifiedSinceDate System.Nullable<System.DateTime>

Returns the object only if it has been modified since the specified time, otherwise returns a PreconditionFailed.

Public Property PartNumber System.Nullable<System.Int32>

Gets and sets the property PartNumber.

Part number of the object being read. This is a positive integer between 1 and 10,000. Effectively performs a 'ranged' HEAD request for the part specified. Useful querying about the size of the part and the number of parts in this object.

Public Property Range System.String

Gets and sets the property Range.

HeadObject returns only the metadata for an object. If the Range is satisfiable, only the ContentLength is affected in the response. If the Range is not satisfiable, S3 returns a 416 - Requested Range Not Satisfiable error.

Public Property RequestPayer Amazon.S3.RequestPayer

Gets and sets the property RequestPayer.

Public Property ResponseCacheControl System.String

Gets and sets the property ResponseCacheControl.

Sets the Cache-Control header of the response.

Public Property ResponseContentDisposition System.String

Gets and sets the property ResponseContentDisposition.

Sets the Content-Disposition header of the response.

Public Property ResponseContentEncoding System.String

Gets and sets the property ResponseContentEncoding.

Sets the Content-Encoding header of the response.

Public Property ResponseContentLanguage System.String

Gets and sets the property ResponseContentLanguage.

Sets the Content-Language header of the response.

Public Property ResponseContentType System.String

Gets and sets the property ResponseContentType.

Sets the Content-Type header of the response.

Public Property ResponseExpires System.Nullable<System.DateTime>

Gets and sets the property ResponseExpires.

Sets the Expires header of the response.

Public Property ServerSideEncryptionCustomerMethod Amazon.S3.ServerSideEncryptionCustomerMethod

Gets and sets the property ServerSideEncryptionCustomerMethod.

Specifies the algorithm to use when encrypting the object (for example, AES256).

This functionality is not supported for directory buckets.

Public Property ServerSideEncryptionCustomerProvidedKey System.String

Gets and sets the property ServerSideEncryptionCustomerProvidedKey.

Specifies the customer-provided encryption key for Amazon S3 to use in encrypting data. This value is used to store the object and then it is discarded; Amazon S3 does not store the encryption key. The key must be appropriate for use with the algorithm specified in the x-amz-server-side-encryption-customer-algorithm header.

This functionality is not supported for directory buckets.

Public Property ServerSideEncryptionCustomerProvidedKeyMD5 System.String

Gets and sets the property ServerSideEncryptionCustomerProvidedKeyMD5.

Specifies the 128-bit MD5 digest of the encryption key according to RFC 1321. Amazon S3 uses this header for a message integrity check to ensure that the encryption key was transmitted without error.

This functionality is not supported for directory buckets.

Public Property UnmodifiedSinceDate System.Nullable<System.DateTime>

Returns the object only if it has not been modified since the specified time, otherwise returns a PreconditionFailed.

Public Property VersionId System.String

Gets and sets the property VersionId.

Version ID used to reference a specific version of the object.

For directory buckets in this API operation, only the null value of the version ID is supported.

Version Information

.NET:
Supported in: 8.0 and newer, Core 3.1

.NET Standard:
Supported in: 2.0

.NET Framework:
Supported in: 4.7.2 and newer