How do link a file user uploaded via pre-signed url to Database?

Question

This is how I was saving user uploaded Files:

f = request.FILES[x]
s = File(file=f, user=curUser)
s.save()

This worked great but it took a lot of bandwidth on my server so I decided to use pre-signed urls.

Now users upload directly to s3 Bucket, however it's not linked to Database.

I tried this which runs after user successfully uploads to S3:

f = default_storage.open(userID + "/" + fileName)
curUser = User.objects.get(userID=userID)
s = File(file=f, user=curUser)
s.save()
f.close()

However, this is just creating a new folder on users directory and uploading it there.

my Models:

class User(models.Model):
    userID = models.CharField(max_length=101,primary_key=True)

class File(models.Model):
    user = models.ForeignKey(to=User, on_delete=models.CASCADE)
    file = models.FileField(max_length=255, upload_to=user_directory_path)

def user_directory_path(instance, filename):
    # file will be uploaded to MEDIA_ROOT/user_<id>/<filename>
    path = instance.user.userID + "/" + filename
    return path

Answer 1

The most common method is to configure the s3 bucket to invoke a lambda function on the file upload event.

Then inside your lambda you update the databse with the uploaded object.

Here is an example: https://docs.aws.amazon.com/lambda/latest/dg/with-s3-example.html

Answer 2

• after doing this if your have done makemigrations and then migrate then table named File will be created in your database.

• which will have two field user and file where file will contains the path of images uploaded.

• now you can access the database like File.objects.all() to get all the rows from File table.