AWS upload implementation

aws.py

'''
Functionality related to AWS file uploads. Separate module was created to
avoid circular imports and for better project structure
'''

import os
import random
import string
import urlparse

from django.conf import settings

import boto
from boto.s3.key import Key


def upload_file_to_aws(user_id, file_to_upload=None, previous_image_url=None):
    '''
    A function to upload images to our Amazon S3 server.
    If file_to_upload keyword will not be provided, an existing image will
    be deleted. If preiovus_image_url and file_to_upload will be provided, an
    existing image will be deleted and a new one will be uploaded. If there's
    a file_to_upload, but no previous_image_url, an image will simply be
    uploaded.
    '''
    # try/except is for debugging purposes, because for some reason errors
    # fail silently in boto:
    try:
        # connect to the bucket
        bucket_name = settings.BUCKET_NAME
        conn = boto.connect_s3(
            settings.AWS_SECRET_ACCESS_KEY,
            settings.AWS_ACCESS_KEY_ID
        )
        bucket = conn.get_bucket(bucket_name)

        # remove old image:
        if previous_image_url:
            path = urlparse.urlparse(previous_image_url).path
            previous_key = bucket.get_key(path)
            bucket.delete_key(previous_key)

        if file_to_upload:
            key = 'property_images/{0}/{1}'.format(
                user_id,
                file_to_upload.name
            )
            key_exists = bucket.get_key(key)
            # create a key to keep track of our file in the storage
            k = Key(bucket)
            # file name already exists:
            if key_exists:
                file_name = os.path.splitext(file_to_upload.name)[0]
                file_extension = os.path.splitext(file_to_upload.name)[1]
                random_hash = ''.join(
                    random.choice(string.lowercase) for i in range(10)
                )
                key = 'property_images/{0}/{1}'.format(
                    user_id,
                    file_name + '-' + random_hash + file_extension
                )
            k.key = key
            temp_file = file_to_upload.temporary_file_path()
            k.set_contents_from_filename(temp_file)
            url = k.generate_url(expires_in=0, query_auth=False)
            # we need to make it public so it can be accessed publicly
            # using a URL like http://s3.amazonaws.com/bucket_name/key
            k.make_public()
            return url
    except Exception as e:
        print(e)