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Querying Object Metadata

Last updated: 2024-02-04 16:24:43

    Overview

    This document provides an overview of APIs and SDK code samples for querying object metadata.
    API
    Operation
    Description
    Querying object metadata
    Queries the metadata of an object

    Querying Object Metadata

    Feature description

    This API is used to query object metadata.

    Method prototype

    head_object(Bucket, Key, **kwargs)

    Sample request

    # -*- coding=utf-8
    from qcloud_cos import CosConfig
    from qcloud_cos import CosS3Client
    import sys
    import os
    import logging
    
    # In most cases, set the log level to INFO. If you need to debug, you can set it to DEBUG and the SDK will print information about the communication with the server.
    logging.basicConfig(level=logging.INFO, stream=sys.stdout)
    
    # 1. Set user attributes such as secret_id, secret_key, and region. Appid has been removed from CosConfig and thus needs to be specified in Bucket, which is formatted as BucketName-Appid.
    secret_id = os.environ['COS_SECRET_ID'] # User `SecretId`. We recommend you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/32675.
    secret_key = os.environ['COS_SECRET_KEY'] # User `SecretKey`. We recommend you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/32675.
    region = 'ap-beijing' # Replace it with the actual region, which can be viewed in the console at https://console.tencentcloud.com/cos5/bucket.
    # For the list of regions supported by COS, visit https://www.tencentcloud.com/document/product/436/6224.
    token = None # Token is required for temporary keys but not permanent keys. For more information about how to generate and use a temporary key, visit https://www.tencentcloud.com/document/product/436/14048.
    scheme = 'https' # Specify whether to use HTTP or HTTPS protocol to access COS. This field is optional and is `https` by default.
    
    config = CosConfig(Region=region, SecretId=secret_id, SecretKey=secret_key, Token=token, Scheme=scheme)
    client = CosS3Client(config)
    
    response = client.head_object(
    Bucket='examplebucket-1250000000',
    Key='exampleobject'
    )
    print(response)

    Sample request with all parameters

    response = client.head_object(
    Bucket='examplebucket-1250000000',
    Key='exampleobject',
    VersionId='string',
    IfModifiedSince='Wed, 28 Oct 2020 20:30:00 GMT',
    )

    Parameter description

    Parameter
    Description
    Type
    Required
    Bucket
    Bucket name in the format of BucketName-APPID
    String
    Yes
    Key
    Object key, which uniquely identifies an object in a bucket. For example, if an object’s access endpoint is examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/doc/pic.jpg, its key is doc/pic.jpg.
    String
    Yes
    VersionId
    Version ID of the object if versioning is enabled
    String
    No
    IfModifiedSince
    Required modification time. Metadata is returned only if the object has been modified after the specified time.
    String
    No

    Response description

    The response contains object metadata in dict format:
    {
    'ETag': '"9a4802d5c99dafe1c04da0a8e7e166bf"',
    'Last-Modified': 'Wed, 28 Oct 2014 20:30:00 GMT',
    'Cache-Control': 'max-age=1000000',
    'Content-Type': 'application/octet-stream',
    'Content-Disposition': 'attachment; filename="filename.jpg"',
    'Content-Encoding': 'gzip',
    'Content-Language': 'zh-cn',
    'Content-Length': '16807',
    'Expires': 'Wed, 28 Oct 2019 20:30:00 GMT',
    'Connection': 'keep-alive',
    'Accept-Ranges': 'bytes',
    'Server': 'tencent-cos',
    'Date': 'Wed, 28 Oct 2019 20:20:00 GMT',
    'x-cos-meta-test': 'test',
    'x-cos-version-id': 'MTg0NDUxODMzMTMwMDM2Njc1ODA',
    'x-cos-hash-crc64ecma': '1220413902487941276',
    'x-cos-request-id': 'NTg3NzQ3ZmVfYmRjMzVfMzE5N182NzczMQ=='
    }
    Parameter
    Description
    Type
    ETag
    For multipart uploads, this value does not represent the MD5 checksum of the object content, but is used only to verify the uniqueness of the object.
    String
    Last-Modified
    Time when the object was last modified
    String
    Cache-Control
    Cache policy. Standard HTTP header
    String
    Content-Type
    Content type. Standard HTTP header
    String
    Content-Disposition
    Filename. Standard HTTP header
    String
    Content-Encoding
    Encoding type. Standard HTTP header
    String
    Content-Language
    Language type. Standard HTTP header
    String
    Content-Length
    Object size
    String
    Expires
    Cache expiration time. Standard HTTP header
    String
    Connection
    Connection method. Standard HTTP header
    String
    Accept-Ranges
    Range request flag. Standard HTTP header
    String
    Server
    Server flag. Standard HTTP header
    String
    Date
    Request date. Standard HTTP header
    String
    x-cos-meta-*
    User-defined object metadata. This parameter must start with x-cos-meta; otherwise, it will be ignored.
    String
    x-cos-hash-crc64ecma
    CRC64 checksum of the file
    String
    x-cos-version-id
    Version ID of the object if versioning is enabled
    String
    x-cos-request-id
    Request ID
    String
    
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