Download an object

Download an object from a Cloud Storage bucket.

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For detailed documentation that includes this code sample, see the following:

Code sample

C++

For more information, see the Cloud Storage C++ API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

namespace gcs = ::google::cloud::storage;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& object_name) {
  gcs::ObjectReadStream stream = client.ReadObject(bucket_name, object_name);

  int count = 0;
  std::string line;
  while (std::getline(stream, line, '\n')) {
    ++count;
  }
  if (stream.bad()) throw google::cloud::Status(stream.status());

  std::cout << "The object has " << count << " lines\n";
}

C#

For more information, see the Cloud Storage C# API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.


using Google.Cloud.Storage.V1;
using System;
using System.IO;

public class DownloadFileSample
{
    public void DownloadFile(
        string bucketName = "your-unique-bucket-name",
        string objectName = "my-file-name",
        string localPath = "my-local-path/my-file-name")
    {
        var storage = StorageClient.Create();
        using var outputFile = File.OpenWrite(localPath);
        storage.DownloadObject(bucketName, objectName, outputFile);
        Console.WriteLine($"Downloaded {objectName} to {localPath}.");
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

import (
	"context"
	"fmt"
	"io"
	"os"
	"time"

	"cloud.google.com/go/storage"
)

// downloadFile downloads an object to a file.
func downloadFile(w io.Writer, bucket, object string, destFileName string) error {
	// bucket := "bucket-name"
	// object := "object-name"
	// destFileName := "file.txt"
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*50)
	defer cancel()

	f, err := os.Create(destFileName)
	if err != nil {
		return fmt.Errorf("os.Create: %w", err)
	}

	rc, err := client.Bucket(bucket).Object(object).NewReader(ctx)
	if err != nil {
		return fmt.Errorf("Object(%q).NewReader: %w", object, err)
	}
	defer rc.Close()

	if _, err := io.Copy(f, rc); err != nil {
		return fmt.Errorf("io.Copy: %w", err)
	}

	if err = f.Close(); err != nil {
		return fmt.Errorf("f.Close: %w", err)
	}

	fmt.Fprintf(w, "Blob %v downloaded to local file %v\n", object, destFileName)

	return nil

}

Java

For more information, see the Cloud Storage Java API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.


import com.google.cloud.storage.Blob;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.nio.file.Paths;

public class DownloadObject {
  public static void downloadObject(
      String projectId, String bucketName, String objectName, String destFilePath) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // The ID of your GCS object
    // String objectName = "your-object-name";

    // The path to which the file should be downloaded
    // String destFilePath = "/local/path/to/file.txt";

    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

    Blob blob = storage.get(BlobId.of(bucketName, objectName));
    blob.downloadTo(Paths.get(destFilePath));

    System.out.println(
        "Downloaded object "
            + objectName
            + " from bucket name "
            + bucketName
            + " to "
            + destFilePath);
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The ID of your GCS file
// const fileName = 'your-file-name';

// The path to which the file should be downloaded
// const destFileName = '/local/path/to/file.txt';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function downloadFile() {
  const options = {
    destination: destFileName,
  };

  // Downloads the file
  await storage.bucket(bucketName).file(fileName).download(options);

  console.log(
    `gs://${bucketName}/${fileName} downloaded to ${destFileName}.`
  );
}

downloadFile().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

use Google\Cloud\Storage\StorageClient;

/**
 * Download an object from Cloud Storage and save it as a local file.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $objectName The name of your Cloud Storage object.
 *        (e.g. 'my-object')
 * @param string $destination The local destination to save the object.
 *        (e.g. '/path/to/your/file')
 */
function download_object(string $bucketName, string $objectName, string $destination): void
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $object = $bucket->object($objectName);
    $object->downloadToFile($destination);
    printf(
        'Downloaded gs://%s/%s to %s' . PHP_EOL,
        $bucketName,
        $objectName,
        basename($destination)
    );
}

Python

For more information, see the Cloud Storage Python API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

from google.cloud import storage


def download_blob(bucket_name, source_blob_name, destination_file_name):
    """Downloads a blob from the bucket."""
    # The ID of your GCS bucket
    # bucket_name = "your-bucket-name"

    # The ID of your GCS object
    # source_blob_name = "storage-object-name"

    # The path to which the file should be downloaded
    # destination_file_name = "local/path/to/file"

    storage_client = storage.Client()

    bucket = storage_client.bucket(bucket_name)

    # Construct a client side representation of a blob.
    # Note `Bucket.blob` differs from `Bucket.get_blob` as it doesn't retrieve
    # any content from Google Cloud Storage. As we don't need additional data,
    # using `Bucket.blob` is preferred here.
    blob = bucket.blob(source_blob_name)
    blob.download_to_filename(destination_file_name)

    print(
        "Downloaded storage object {} from bucket {} to local file {}.".format(
            source_blob_name, bucket_name, destination_file_name
        )
    )

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

def download_file bucket_name:, file_name:, local_file_path:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  # The ID of your GCS object
  # file_name = "your-file-name"

  # The path to which the file should be downloaded
  # local_file_path = "/local/path/to/file.txt"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket  = storage.bucket bucket_name, skip_lookup: true
  file    = bucket.file file_name

  file.download local_file_path

  puts "Downloaded #{file.name} to #{local_file_path}"
end

What's next

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