Object Storage Service:Query files (Go SDK V1)

Usage notes

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

• To query objects, you must have the oss:GetObject permission. For more information, see Attach a custom policy to a RAM user.

• Only objects in the CSV and JSON formats can be queried by using SelectObject.

Sample code

package main

import (
	"io"
	"log"

	"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 set.
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		log.Fatalf("Error getting credentials: %v", err)
	}

	// Create an OSSClient instance.
	// Set yourEndpoint to the Endpoint of the bucket. For example, for a bucket in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. For other regions, set the Endpoint as needed.
	// Set yourRegion to the region where the bucket is located. For example, for a bucket in the China (Hangzhou) region, set the region to cn-hangzhou. For other regions, set the region as needed.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Set the signature version.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Error creating OSS client: %v", err)
	}

	// Specify the bucket name. For example, examplebucket.
	bucketName := "examplebucket"
	bucket, err := client.Bucket(bucketName)
	if err != nil {
		log.Fatalf("Error getting bucket: %v", err)
	}

	// Specify the full path of the object. The full path cannot contain the bucket name. For example, exampledir/exampledata.csv.
	objectKey := "exampledir/exampledata.csv"
	// Specify the full path of the local CSV file. For example, D:\\localpath\\exampledata.csv.
	localCsvFile := "D:\\localpath\\exampledata.csv"

	// Upload the local file to OSS.
	if err := bucket.PutObjectFromFile(objectKey, localCsvFile); err != nil {
		log.Fatalf("Error uploading file: %v", err)
	}

	// Use a SELECT statement to query data from the file.
	selectRequest := oss.SelectRequest{
		Expression: `select * from ossobject`,
	}

	// Execute the SELECT request.
	body, err := bucket.SelectObject(objectKey, selectRequest)
	if err != nil {
		log.Fatalf("Error selecting object: %v", err)
	}
	defer body.Close()

	// Read the content.
	content, err := io.ReadAll(body)
	if err != nil {
		log.Fatalf("Error reading content: %v", err)
	}

	// Print the result.
	log.Printf("Selected content: %s", string(content))
}

package main

import (
	"io"
	"log"

	"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 set.
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		log.Fatalf("Error getting credentials: %v", err)
	}

	// Create an OSSClient instance.
	// Set yourEndpoint to the Endpoint of the bucket. For example, for a bucket in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. For other regions, set the Endpoint as needed.
	// Set yourRegion to the region where the bucket is located. For example, for a bucket in the China (Hangzhou) region, set the region to cn-hangzhou. For other regions, set the region as needed.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Set the signature version.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Error creating OSS client: %v", err)
	}

	// Specify the bucket name. For example, examplebucket.
	bucketName := "examplebucket"
	bucket, err := client.Bucket(bucketName)
	if err != nil {
		log.Fatalf("Error getting bucket: %v", err)
	}

	// Specify the full path of the object. The full path cannot contain the bucket name. For example, exampledir/exampledata.json.
	objectKey := "exampledir/exampledata.json"
	// Specify the full path of the local JSON file. For example, D:\\localpath\\exampledata.json.
	localJsonFile := "D:\\localpath\\exampledata.json"

	// Upload the local file to OSS.
	if err := bucket.PutObjectFromFile(objectKey, localJsonFile); err != nil {
		log.Fatalf("Error uploading file: %v", err)
	}

	// Use a SELECT statement to query data from the file.
	selectRequest := oss.SelectRequest{
		Expression: `select * from ossobject`,
	}

	// Execute the SELECT request.
	body, err := bucket.SelectObject(objectKey, selectRequest)
	if err != nil {
		log.Fatalf("Error selecting object: %v", err)
	}
	defer body.Close()

	// Read the content.
	content, err := io.ReadAll(body)
	if err != nil {
		log.Fatalf("Error reading content: %v", err)
	}

	// Print the result.
	log.Printf("Selected content: %s", string(content))
}

References

• For the complete sample code for querying files, see the GitHub example.

• For more information about the API operation for querying files, see SelectObject.