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Object Storage Service:Download objects

Last Updated:Oct 08, 2023

By default, when you call the GetObject operation on an object in a versioning-enabled bucket, only the current version of the object is returned.

Background information

When you call the GetObject operation to download an object in a bucket, you may obtain one of the following results:

  • If the current version of the object is a delete marker, OSS returns 404 Not Found.

  • If a version ID of the object is specified in the request, OSS returns the specified version of the object. If the version ID is set to null in the request, OSS returns the version whose version ID is null.

  • If the version ID specified in the request is the version ID of a delete marker, OSS returns 405 Method Not Allowed.

Usage notes

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

  • In this topic, access credentials are obtained from environment variables. For more information about how to configure access credentials, see Configure access credentials.

  • 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 download an object, you must have the oss:GetObject permission. For more information, see Common examples of RAM policies.

Sample code

The following code provides an example on how to download an object:

package main

import (
  "fmt"
  "net/http"
  "os"  

  "github.com/aliyun/aliyun-oss-go-sdk/oss"
)

func main() {
    /// 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. 
    provider, err := oss.NewEnvironmentVariableCredentialsProvider()
    if err != nil {
        fmt.Println("Error:", err)
        os.Exit(-1)
    }

    // Create an OSSClient instance. 
    // 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. Specify your actual endpoint. 
    client, err := oss.New("yourEndpoint", "", "", oss.SetCredentialsProvider(&provider))
    if err != nil {
      fmt.Println("Error:", err)
      os.Exit(-1)
  }

  // Specify the name of the bucket. 
  bucket, err := client.Bucket("<yourBucketName>")
  if err != nil {
    fmt.Println("Error:", err)
    os.Exit(-1)
  }

  var retHeader http.Header
  // Download the version whose ID is yourObjectVersionId to the cache. 
  // Specify the full path of the object. Do not include the bucket name in the full path. 
  _, err = bucket.GetObject("youObjectName", oss.VersionId("yourObjectVersionId"), oss.GetResponseHeader(&retHeader))
  if err != nil {
    fmt.Println("Error:", err)
    os.Exit(-1)
  }
  // Display the value of x-oss-version-id. 
  fmt.Println("x-oss-version-id:",  oss.GetVersionId(retHeader))
}

References

  • For the complete sample code that is used to download an object, visit GitHub.

  • For more information about the API operation that you can call to download an object, see GetObject.