In fact, retrieve the file from an S3 bucket and save it to your local

Question

In fact, retrieve the file from an S3 bucket and save it to your local

I've been attempting to retrieve an s3 file from my bucket using this function:

async Export()
{
  const myKey = '...key...'
   const mySecret = '...secret...'
  AWS.config.update(
    {
      accessKeyId: myKey,
      secretAccessKey: mySecret
    }
  );

  var s3 = new AWS.S3();

  s3.getObject({
    Bucket: '...bucket...',
    Key: '...filepath...'
  },
  function(error, data)
  {
    if (error != null)
    {
      alert("Failed to retrieve object: " + error)
    }
    else {
      alert("Loaded " + data.ContentLength + " bytes")
    }
  })
 }

After running the function, I receive a message indicating that I have successfully loaded a file consisting of a certain number of bytes. However, my main objective is to download the file onto my local machine. Do I need to implement a file stream mechanism here?

Additional Information

We are utilizing Angular Typescript, not AngularJS

angular typescript amazon-web-services amazon-s3

Answer 1

Answer №1

A smart way to handle file downloads is by retrieving a signed URL from S3 instead of directly saving it as a stream. This allows for more dynamic and secure downloading options. Check out the following code snippet for guidance:

const AWS = require('aws-sdk')
const s3 = new AWS.S3()
AWS.config.update({accessKeyId: 'your access key', secretAccessKey: 'you secret key'})

const myBucket = 'bucket-name'
const myKey = 'path/to/your/key/file.extension'
const signedUrlExpireSeconds = 60 * 5 // expiry time in seconds.

const url = s3.getSignedUrl('getObject', {
  Bucket: myBucket,
  Key: myKey,
  Expires: signedUrlExpireSeconds
})

Utilize this generated URL in your front-end to initiate the download action:

function download(url){
  $('<iframe>', { id:'idown', src:url }).hide().appendTo('body').click();
}
$("#downloadButton").click(function(){
  $.ajax({
    url: 'example.com/your_end_point',
    success: function(url){
      download(url);
    }
  })
});

Answer 2

A smart way to handle file downloads is by retrieving a signed URL from S3 instead of directly saving it as a stream. This allows for more dynamic and secure downloading options. Check out the following code snippet for guidance:

const AWS = require('aws-sdk')
const s3 = new AWS.S3()
AWS.config.update({accessKeyId: 'your access key', secretAccessKey: 'you secret key'})

const myBucket = 'bucket-name'
const myKey = 'path/to/your/key/file.extension'
const signedUrlExpireSeconds = 60 * 5 // expiry time in seconds.

const url = s3.getSignedUrl('getObject', {
  Bucket: myBucket,
  Key: myKey,
  Expires: signedUrlExpireSeconds
})

Utilize this generated URL in your front-end to initiate the download action:

function download(url){
  $('<iframe>', { id:'idown', src:url }).hide().appendTo('body').click();
}
$("#downloadButton").click(function(){
  $.ajax({
    url: 'example.com/your_end_point',
    success: function(url){
      download(url);
    }
  })
});

Answer 3

Answer №2

After some investigation, I discovered that utilizing the backend is the most effective solution to this issue. I encountered a problem where I was trying to create an anchor tag that would download a file from an S3 URL upon clicking, but instead it would open the object in a new tab. The root of the problem turned out to be my Response Content Disposition. Here is how I resolved it by ensuring the file downloads directly to the filesystem:

Backend (I opted for Django and boto3):

    def get_file(self, obj):      
        client = boto3.client('s3', aws_access_key_id=settings.AWS_ACCESS_KEY_ID,
                              aws_secret_access_key=settings.AWS_SECRET_ACCESS_KEY)

        return client.generate_presigned_url(
            'get_object',
            Params={
                'Bucket': settings.AWS_STORAGE_BUCKET_NAME,
                'Key': obj.key,
                'ResponseContentDisposition': 'attachment',
            },
            ExpiresIn=600)

Frontend (leveraging Angular):

<a [href]="what_i_returned_from_backend" [download]="answer.png" target="_self" rel="noopener noreferrer">Download</a>

Answer 4

After some investigation, I discovered that utilizing the backend is the most effective solution to this issue. I encountered a problem where I was trying to create an anchor tag that would download a file from an S3 URL upon clicking, but instead it would open the object in a new tab. The root of the problem turned out to be my Response Content Disposition. Here is how I resolved it by ensuring the file downloads directly to the filesystem:

Backend (I opted for Django and boto3):

    def get_file(self, obj):      
        client = boto3.client('s3', aws_access_key_id=settings.AWS_ACCESS_KEY_ID,
                              aws_secret_access_key=settings.AWS_SECRET_ACCESS_KEY)

        return client.generate_presigned_url(
            'get_object',
            Params={
                'Bucket': settings.AWS_STORAGE_BUCKET_NAME,
                'Key': obj.key,
                'ResponseContentDisposition': 'attachment',
            },
            ExpiresIn=600)

Frontend (leveraging Angular):

<a [href]="what_i_returned_from_backend" [download]="answer.png" target="_self" rel="noopener noreferrer">Download</a>

Answer 5

Answer №3

In my Spring + Angular web application, there is a list of files available for download by users. When a user clicks on a file name, the UI sends a request to the API for a temporary download link, which is generated using AmazonS3.generatePresignedUrl().

  public String generateUrlByKey(String key) {
    log.debug("S3 - Get file OutputStream by key: {}", key);

    Calendar calendar = Calendar.getInstance();
    calendar.setTime(new Date());
    calendar.add(Calendar.DATE, 1);
    GeneratePresignedUrlRequest request = new GeneratePresignedUrlRequest(s3Properties.getBucket(),
                                                                          key,
                                                                          HttpMethod.GET);
    request.setExpiration(calendar.getTime());

    ResponseHeaderOverrides headerOverrides = new ResponseHeaderOverrides();
    headerOverrides.setContentDisposition("attachment");
    request.withResponseHeaders(headerOverrides);

    return amazonS3.generatePresignedUrl(request).toString();
  }

It is important to note the line: headerOverrides.setContentDisposition("attachment"); This ensures that when a user clicks on a file link, the file is downloaded instead of opened in the browser.

I am dynamically clicking on file links after obtaining the link in the UI:

  this.fileService.getTempUrlByFileId($event.id).subscribe({
    next: (url) => {
      const link: HTMLAnchorElement = document.createElement("a");
      link.href = url;
      document.body.appendChild(link);
      link.click();
      document.body.removeChild(link);
    }
  });

The implementation of getTempUrlByFileId method:

  getTempUrlByFileId(id: number): Observable<string> {
    const url = `${this.API}/${id}`
    // @ts-ignore
    return this.http.get<string>(url, { responseType: 'text' });
  }

Answer 6

In my Spring + Angular web application, there is a list of files available for download by users. When a user clicks on a file name, the UI sends a request to the API for a temporary download link, which is generated using AmazonS3.generatePresignedUrl().

  public String generateUrlByKey(String key) {
    log.debug("S3 - Get file OutputStream by key: {}", key);

    Calendar calendar = Calendar.getInstance();
    calendar.setTime(new Date());
    calendar.add(Calendar.DATE, 1);
    GeneratePresignedUrlRequest request = new GeneratePresignedUrlRequest(s3Properties.getBucket(),
                                                                          key,
                                                                          HttpMethod.GET);
    request.setExpiration(calendar.getTime());

    ResponseHeaderOverrides headerOverrides = new ResponseHeaderOverrides();
    headerOverrides.setContentDisposition("attachment");
    request.withResponseHeaders(headerOverrides);

    return amazonS3.generatePresignedUrl(request).toString();
  }

It is important to note the line: headerOverrides.setContentDisposition("attachment"); This ensures that when a user clicks on a file link, the file is downloaded instead of opened in the browser.

I am dynamically clicking on file links after obtaining the link in the UI:

  this.fileService.getTempUrlByFileId($event.id).subscribe({
    next: (url) => {
      const link: HTMLAnchorElement = document.createElement("a");
      link.href = url;
      document.body.appendChild(link);
      link.click();
      document.body.removeChild(link);
    }
  });

The implementation of getTempUrlByFileId method:

  getTempUrlByFileId(id: number): Observable<string> {
    const url = `${this.API}/${id}`
    // @ts-ignore
    return this.http.get<string>(url, { responseType: 'text' });
  }

Answer 7

Answer №4

When dealing with browser cache issues, an effective solution is to navigate to the Chrome Dev Tools network tab and select "disable cache". This action will usually resolve any download issues. However, if you attempt to refresh the page without disabling the cache, downloading may fail consistently due to a CORS error.

Answer 8

When dealing with browser cache issues, an effective solution is to navigate to the Chrome Dev Tools network tab and select "disable cache". This action will usually resolve any download issues. However, if you attempt to refresh the page without disabling the cache, downloading may fail consistently due to a CORS error.

In fact, retrieve the file from an S3 bucket and save it to your local

Additional Information

Answer №1

Answer №2

Answer №3

Answer №4

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