How to add object tags to files by using Go SDK V2 - Object Storage Service

Object Storage Service (OSS) supports object tagging to classify objects in buckets. This topic describes how to add object tags using the OSS SDK for Go V2.

Notes

The sample code in this topic uses the region ID cn-hangzhou for the China (Hangzhou) region. By default, public endpoints are used to access resources in a bucket. If you want to access resources in the bucket from other Alibaba Cloud services in the same region, use an internal endpoint. For more information about the regions and endpoints that OSS supports, see OSS regions and endpoints.
In this topic, access credentials are retrieved from environment variables. For more information about how to configure access credentials, see Configure access credentials.
To add object tags, you must have the oss:PutObjectTagging permission. For more information, see Grant custom permissions to RAM users.

Add tags when you upload an object

Add tags to an object during a simple upload

You can use the following code to add object tags when you upload an object.

package main

import (
	"context"
	"flag"
	"log"
	"strings"

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

// Define global variables.
var (
	region     string // The region in which the bucket is located.
	bucketName string // The name of the bucket.
	objectName string // The name of the object.
)

// The init function is used to initialize command-line parameters.
func init() {
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
	flag.StringVar(&objectName, "object", "", "The name of the object.")
}

func main() {
	// Parse command-line parameters.
	flag.Parse()

	// Check whether the bucket name is empty.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required")
	}

	// Check whether the region is empty.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}

	// Check whether the object name is empty.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, object name required")
	}

	// Define the content to upload.
	content := "hi oss"

	// Load the default configurations and set the credential provider and region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	// Create an OSS client.
	client := oss.NewClient(cfg)

	// Create a request to upload the object.
	request := &oss.PutObjectRequest{
		Bucket:  oss.Ptr(bucketName),                // The name of the bucket.
		Key:     oss.Ptr(objectName),                // The name of the object.
		Body:    strings.NewReader(content),         // The content to upload.
		Tagging: oss.Ptr("tag1=value1&tag2=value2"), // Specify the actual object tags.
	}

	// Execute the request to upload the object.
	result, err := client.PutObject(context.TODO(), request)
	if err != nil {
		log.Fatalf("failed to put object %v", err)
	}

	// Print the result of the object upload.
	log.Printf("put object result:%#v\n", result)
}

Add tags to an object during a multipart upload

You can use the following code to add object tags during a multipart upload.

package main

import (
	"bufio"
	"bytes"
	"context"
	"flag"
	"io"
	"log"
	"os"
	"sync"

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

// Define global variables.
var (
	region     string // The region in which the bucket is located.
	bucketName string // The name of the source bucket.
	objectName string // The name of the source object.

)

// The init function is used to initialize command-line parameters.
func init() {
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	flag.StringVar(&bucketName, "bucket", "", "The name of the source bucket.")
	flag.StringVar(&objectName, "object", "", "The name of the source object.")
}

func main() {
	// Parse command-line parameters.
	flag.Parse()

	// Define the upload ID.
	var uploadId string

	// Check whether the name of the source bucket is empty.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, source bucket name required")
	}

	// Check whether the region is empty.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}

	// Check whether the name of the source object is empty.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, source object name required")
	}

	// Load the default configurations and set the credential provider and region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	// Create an OSS client.
	client := oss.NewClient(cfg)

	// Initialize the multipart upload request.
	initRequest := &oss.InitiateMultipartUploadRequest{
		Bucket:  oss.Ptr(bucketName),
		Key:     oss.Ptr(objectName),
		Tagging: oss.Ptr("tag1=value1&tag2=value2"), // Specify the actual object tags.
	}

	// Execute the request to initiate the multipart upload.
	initResult, err := client.InitiateMultipartUpload(context.TODO(), initRequest)
	if err != nil {
		log.Fatalf("failed to initiate multipart upload %v", err)
	}

	// Print the result of the multipart upload initialization.
	log.Printf("initiate multipart upload result:%#v\n", *initResult.UploadId)
	uploadId = *initResult.UploadId

	// Initialize the wait group and mutex.
	var wg sync.WaitGroup
	var parts []oss.UploadPart
	count := 3
	var mu sync.Mutex

	// Read the content of the local file into the memory. Replace yourLocalFile with the actual name and path of the local file.
	file, err := os.Open("/Users/leyinhui/Downloads/iTerm2")
	if err != nil {
		log.Fatalf("failed to open local file %v", err)
	}
	defer file.Close()

	bufReader := bufio.NewReader(file)
	content, err := io.ReadAll(bufReader)
	if err != nil {
		log.Fatalf("failed to read local file %v", err)
	}
	log.Printf("file size: %d\n", len(content))

	// Calculate the size of each part.
	chunkSize := len(content) / count
	if chunkSize == 0 {
		chunkSize = 1
	}

	// Start multiple goroutines to upload parts.
	for i := 0; i < count; i++ {
		start := i * chunkSize
		end := start + chunkSize
		if i == count-1 {
			end = len(content)
		}

		wg.Add(1)
		go func(partNumber int, start, end int) {
			defer wg.Done()

			// Create a request to upload a part.
			partRequest := &oss.UploadPartRequest{
				Bucket:     oss.Ptr(bucketName),                 // The name of the destination bucket.
				Key:        oss.Ptr(objectName),                 // The name of the destination object.
				PartNumber: int32(partNumber),                   // The part number.
				UploadId:   oss.Ptr(uploadId),                   // The upload ID.
				Body:       bytes.NewReader(content[start:end]), // The content of the part.
			}

			// Send the request to upload the part.
			partResult, err := client.UploadPart(context.TODO(), partRequest)
			if err != nil {
				log.Fatalf("failed to upload part %d: %v", partNumber, err)
			}

			// Record the result of the part upload.
			part := oss.UploadPart{
				PartNumber: partRequest.PartNumber,
				ETag:       partResult.ETag,
			}

			// Use a mutex to protect shared data.
			mu.Lock()
			parts = append(parts, part)
			mu.Unlock()
		}(i+1, start, end)
	}

	// Wait for all goroutines to complete.
	wg.Wait()

	// Complete the multipart upload.
	request := &oss.CompleteMultipartUploadRequest{
		Bucket:   oss.Ptr(bucketName),
		Key:      oss.Ptr(objectName),
		UploadId: oss.Ptr(uploadId),
		CompleteMultipartUpload: &oss.CompleteMultipartUpload{
			Parts: parts,
		},
	}
	result, err := client.CompleteMultipartUpload(context.TODO(), request)
	if err != nil {
		log.Fatalf("failed to complete multipart upload %v", err)
	}

	// Print the result of the completed multipart upload.
	log.Printf("complete multipart upload result:%#v\n", result)
}

Add tags to an object during an append upload

You can use the following code to add object tags during an append upload.

package main

import (
	"context"
	"flag"
	"log"
	"strings"

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

// Define global variables.
var (
	region     string
	bucketName string
	objectName string
)

// The init function is used to initialize command-line parameters.
func init() {
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
	flag.StringVar(&objectName, "object", "", "The name of the object.")
}

func main() {
	// Parse command-line parameters.
	flag.Parse()

	// Define the initial position for appending the file.
	var (
		position = int64(0)
	)

	// Check whether the bucket name is empty.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required")
	}

	// Check whether the region is empty.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}

	// Check whether the object name is empty.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, object name required")
	}

	// Load the default configurations and set the credential provider and region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	// Create an OSS client.
	client := oss.NewClient(cfg)

	// Define the content to append.
	content := "hi append object"

	// Create an AppendObject request.
	request := &oss.AppendObjectRequest{
		Bucket:   oss.Ptr(bucketName),
		Key:      oss.Ptr(objectName),
		Position: oss.Ptr(position),
		Body:     strings.NewReader(content),
		Tagging:  oss.Ptr("tag1=value1&tag2=value2"), //Specify the actual object tags.
	}

	// Execute the first AppendObject request and process the result.
	// The position of the first append upload is 0. The return value contains the position for the next append upload.
	result, err := client.AppendObject(context.TODO(), request)
	if err != nil {
		log.Fatalf("failed to append object %v", err)
	}

	// Create the second AppendObject request.
	request = &oss.AppendObjectRequest{
		Bucket:   oss.Ptr(bucketName),
		Key:      oss.Ptr(objectName),
		Position: oss.Ptr(result.NextPosition), //Obtain NextPosition from the return value of the first AppendObject request.
		Body:     strings.NewReader("hi append object"),
	}

	// Execute the second AppendObject request and process the result.
	result, err = client.AppendObject(context.TODO(), request)
	if err != nil {
		log.Fatalf("failed to append object %v", err)
	}

	log.Printf("append object result:%#v\n", result)
}

Add tags to an object when you copy the object

You can use the following code to add object tags when you copy an object.

package main

import (
	"context"
	"flag"
	"log"

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

// Define global variables.
var (
	region         string // The region in which the bucket is located.
	srcBucketName  string // The name of the source bucket.
	srcObjectName  string // The name of the source object.
	destBucketName string // The name of the destination bucket.
	destObjectName string // The name of the destination object.
)

// The init function is used to initialize command-line parameters.
func init() {
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	flag.StringVar(&srcBucketName, "src-bucket", "", "The name of the source bucket.")
	flag.StringVar(&srcObjectName, "src-object", "", "The name of the source object.")
	flag.StringVar(&destBucketName, "dest-bucket", "", "The name of the destination bucket.")
	flag.StringVar(&destObjectName, "dest-object", "", "The name of the destination object.")
}

func main() {
	// Parse command-line parameters.
	flag.Parse()

	// Check whether the name of the source bucket is empty.
	if len(srcBucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, source bucket name required")
	}

	// Check whether the region is empty.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}

	// If the destination bucket name is not specified, the source bucket name is used.
	if len(destBucketName) == 0 {
		destBucketName = srcBucketName
	}

	// Check whether the name of the source object is empty.
	if len(srcObjectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, source object name required")
	}

	// Check whether the name of the destination object is empty.
	if len(destObjectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, destination object name required")
	}

	// Load the default configurations and set the credential provider and region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	// Create an OSS client.
	client := oss.NewClient(cfg)

	// Create a request to copy the object.
	copyRequest := &oss.CopyObjectRequest{
		Bucket:           oss.Ptr(destBucketName),            // The name of the destination bucket.
		Key:              oss.Ptr(destObjectName),            // The name of the destination object.
		SourceKey:        oss.Ptr(srcObjectName),             // The name of the source object.
		SourceBucket:     oss.Ptr(srcBucketName),             // The name of the source bucket.
		StorageClass:     oss.StorageClassStandard,           // Set the storage class to Standard.
		TaggingDirective: oss.Ptr("Replace"),                 // Do not copy the tags of the source object.
		Tagging:          oss.Ptr("tag1=value1&tag2=value2"), // Specify the actual object tags.
	}

	// Execute the copy operation and process the result.
	copyResult, err := client.CopyObject(context.TODO(), copyRequest)
	if err != nil {
		log.Fatalf("failed to copy object: %v", err)
	}

	// Print the result of the copy operation.
	log.Printf("copy object result:%#v\n", copyResult)

}

Add tags to or modify the tags of an uploaded object

If an object is uploaded without tags or the existing tags do not meet your requirements, you can add or modify the tags of the object after it is uploaded.

You can use the following code to add tags to or modify the tags of an uploaded object.

package main

import (
	"context"
	"flag"
	"log"

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

// Define global variables.
var (
	region     string // The region in which the bucket is located.
	bucketName string // The name of the bucket.
	objectName string // The name of the object.
)

// The init function is used to initialize command-line parameters.
func init() {
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
	flag.StringVar(&objectName, "object", "", "The name of the object.")
}

func main() {
	// Parse command-line parameters.
	flag.Parse()

	// Check whether the region is empty.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}

	// Check whether the bucket name is empty.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required")
	}

	// Check whether the object name is empty.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, object name required")
	}

	// Load the default configurations and set the credential provider and region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	// Create an OSS client.
	client := oss.NewClient(cfg)

	// Create a request to set object tags.
	putRequest := &oss.PutObjectTaggingRequest{
		Bucket: oss.Ptr(bucketName), // The name of the bucket.
		Key:    oss.Ptr(objectName), // The name of the object.
		Tagging: &oss.Tagging{
			TagSet: &oss.TagSet{
				Tags: []oss.Tag{
					{
						Key:   oss.Ptr("k1"), // The tag key.
						Value: oss.Ptr("v1"), // The tag value.
					},
					{
						Key:   oss.Ptr("k2"), // The tag key.
						Value: oss.Ptr("v2"), // The tag value.
					},
				},
			},
		},
	}

	// Send the request to set object tags.
	putResult, err := client.PutObjectTagging(context.TODO(), putRequest)
	if err != nil {
		log.Fatalf("failed to put object tagging %v", err)
	}

	// Print the result of setting object tags.
	log.Printf("put object tagging result:%#v\n", putResult)
}

References

For the complete sample code for setting object tags, see the GitHub example.
For more information about the API operation for setting object tags, see PutObjectTagging.