Object Storage Service:Synchronous processing (Go SDK V2)

Usage notes

• The sample code in this topic uses the China (Hangzhou) region (region ID: cn-hangzhou) as an example. By default, a public endpoint is used. If you want to access OSS from other Alibaba Cloud products in the same region, use an internal endpoint. For more information about the mappings between OSS-supported regions and endpoints, see OSS regions and endpoints.

• This topic provides an example of obtaining access credentials from environment variables. For more information about how to configure access credentials, see Configure access credentials.

Method definition

func (c *Client) ProcessObject(ctx context.Context, request *ProcessObjectRequest, optFns ...func(*Options)) (*ProcessObjectResult, error)

Request parameters

Return values

Sample code

The following sample code shows how to use Go SDK V2 to scale an image and save the processed image to a specified bucket.

package main

import (
	"context"
	"encoding/base64"
	"flag"
	"fmt"
	"log"

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

var (
	region     string
	bucketName string
	objectName string
)

// The init function is executed before the main function to initialize the program.
func init() {
	// Set a command-line parameter to specify the region.
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	// Set a command-line parameter to specify the bucket name.
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
	// Set a command-line parameter to specify the name of the image to be processed.
	flag.StringVar(&objectName, "object", "", "The name of the object.")
}

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

	// Check whether the region information is provided. If not, print the default parameters and exit the program.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}
	// Check whether the bucket name is provided. If not, print the default parameters and exit the program.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required")
	}
	// Check whether the object name is provided. If not, print the default parameters and exit the program.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, object name required")
	}

	// Create a configuration object, and use environment variables as the credential provider and the specified region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	client := oss.NewClient(cfg) // Create a new OSS client using the configuration.

	// Specify the name of the bucket used to store the processed image. The bucket must be in the same region as the bucket that stores the source image.
	targetBucketName := bucketName
	// Specify the name of the processed image. If the image is not in the root directory of the bucket, you must include the full path of the file, for example, exampledir/example.jpg.
	targetImageName := "exampledir/example.jpg"
	// Resize the image to a fixed width and height of 100 px and save it to the specified bucket.
	style := "image/resize,m_fixed,w_100,h_100"
	process := fmt.Sprintf("%s|sys/saveas,o_%v,b_%v", style, base64.URLEncoding.EncodeToString([]byte(targetImageName)), base64.URLEncoding.EncodeToString([]byte(targetBucketName)))

	// Build a ProcessObjectRequest to initiate synchronous processing for a specific object.
	request := &oss.ProcessObjectRequest{
		Bucket:  oss.Ptr(bucketName), // Specify the name of the bucket to operate on.
		Key:     oss.Ptr(objectName), // Specify the name of the image to process.
		Process: oss.Ptr(process),    // Specify the processing instruction.
	}

	// Execute the request to synchronously process the object and receive the return value.
	result, err := client.ProcessObject(context.TODO(), request)
	if err != nil {
		log.Fatalf("failed to process object %v", err)
	}

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

Scenarios

package main

import (
	"context"
	"encoding/base64"
	"flag"
	"fmt"
	"log"

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

var (
	region     string
	bucketName string
	objectName string
)

// The init function is executed before the main function to initialize the program.
func init() {
	// Set a command-line parameter to specify the region. The default value is an empty string.
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	// Set a command-line parameter to specify the bucket name. The default value is an empty string.
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
	// Set a command-line parameter to specify the name of the image to be processed.
	flag.StringVar(&objectName, "object", "", "The name of the object.")
}

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

	// Check whether the region information is provided. If not, print the default parameters and exit the program.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}
	// Check whether the bucket name is provided. If not, print the default parameters and exit the program.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required")
	}
	// Check whether the object name is provided. If not, print the default parameters and exit the program.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, object name required")
	}

	// Create a configuration object, and use environment variables as the credential provider and the specified region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	client := oss.NewClient(cfg) // Create a new OSS client using the configuration.

	// Specify the watermark content.
	content := "Copyright Alibaba Cloud"

	// Generate a blind watermark for the image.
	encodedContent := base64.URLEncoding.EncodeToString([]byte(content))
	style := fmt.Sprintf("image/blindwatermark,content_%s", encodedContent)
	targetImageName := "targetDir/target.jpg"
	process := fmt.Sprintf("%s|sys/saveas,o_%s,b_%s", style, base64.URLEncoding.EncodeToString([]byte(targetImageName)), base64.URLEncoding.EncodeToString([]byte(bucketName)))

	// Build a ProcessObjectRequest to initiate synchronous processing for a specific object.
	request := &oss.ProcessObjectRequest{
		Bucket:  oss.Ptr(bucketName), // Specify the name of the bucket to operate on.
		Key:     oss.Ptr(objectName), // Specify the name of the object to process.
		Process: oss.Ptr(process),    // Specify the processing instruction.
	}

	// Execute the request to synchronously process the object and receive the return value.
	result, err := client.ProcessObject(context.TODO(), request)
	if err != nil {
		log.Fatalf("failed to process object %v", err)
	}

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

References

• For more information about image processing parameters, see Image processing parameters.

• For more information about the synchronous processing feature, see Synchronous processing.

• For more information about the synchronous processing feature, see the ProcessObject API operation.