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Querying Object Metadata
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Last updated: 2024-02-02 15:51:37
Querying Object Metadata
Last updated: 2024-02-02 15:51:37
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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

The API (HEAD Object) is used to query object metadata.

Method prototype

func (s *ObjectService) Head(ctx context.Context, key string, opt *ObjectHeadOptions) (*Response, error)

Sample request

package main

import (
    "context"
    "github.com/tencentyun/cos-go-sdk-v5"
    "net/http"
    "net/url"
    "os"
)

func main(){
    // Bucket name in the format of `BucketName-APPID` (`APPID` is required), which can be viewed in the COS console at https://console.cloud.tencent.com/cos5/bucket.
    // Replace it with your region, which can be viewed in the COS console at https://console.cloud.tencent.com/. For more information about regions, visit https://intl.cloud.tencent.com/document/product/436/6224.
    u, _ := url.Parse("https://examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com")
    b := &cos.BaseURL{BucketURL: u}
    client := cos.NewClient(b, &http.Client{
        Transport: &cos.AuthorizationTransport{
            // Get the key from environment variables
            // Environment variable `SECRETID` refers to the user's `SecretId`, which can be viewed in the CAM console at https://console.cloud.tencent.com/cam/capi.
            SecretID: os.Getenv("SECRETID"),  // 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://cloud.tencent.com/document/product/598/37140.
            // Environment variable `SECRETKEY` refers to the user's `SecretKey`, which can be viewed in the CAM console at https://console.cloud.tencent.com/cam/capi.
            SecretKey: os.Getenv("SECRETKEY"),  // 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://cloud.tencent.com/document/product/598/37140.
        },
    })
    key := "exampleobject"
    _, err := client.Object.Head(context.Background(), key, nil)
    if err != nil{
        panic(err)
    }
}

Field description

type ObjectHeadOptions struct {
    IfModifiedSince string 
}
Parameter
Description
Type
Required
key
Object key, unique identifier of an object in a bucket. For example, if the object endpoint is examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/doc/pic.jpg, its object key is doc/pic.jpg
string
Yes
IfModifiedSince
Returned only if the object is modified after the specified time
String
No

Response description

{
    'Content-Type': 'application/octet-stream',
    'Content-Length': '16807',
    'ETag': '"9a4802d5c99dafe1c04da0a8e7e166bf"',
    'Last-Modified': 'Wed, 28 Oct 2014 20:30:00 GMT',
    'X-Cos-Request-Id': 'NTg3NzQ3ZmVfYmRjMzVfMzE5N182NzczMQ=='
}
The result can be obtained from the response.
resp, err := client.Object.Head(context.Background(), key, nil)
contentType := resp.Header.Get("Content-Type")
contentLength := resp.Header.Get("Content-Length")
etag := resp.Header.Get("ETag")
reqid := resp.Header.Get("X-Cos-Request-Id")

Parameter
Description
Type
Metadata
Metadata of the queried file, including ETag and X-Cos-Request-Id. The metadata of the configured file is also returned.
String

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