Automatically update images - django

Question

I'd like to implement a functionality in an app of mine, but I don't know how to go about it. What I want is this: I have a model class that uses imagekit to save its images, and I'd like to have the users being able to update the images easily for the vehicles without having to edit each respective vehicle record.
How they'll do this is that there will be a folder named originals and it'll contain folders for each vehicle in the format <stock_number>/PUBLIC If a user moves images into the PUBLIC folder for a vehicle, when the script is executed, it'll compare those images with the current ones and update them if those in the PUBLIC folder are newer. If the record has no images, then they will be added. Also, if the images have been deleted from the site_media directory, then their links should be deleted from the database.
How can I go about this in an efficient way? My models are as below:
class Photo(ImageModel):
name = models.CharField(max_length = 100)
original_image = models.ImageField(upload_to = 'photos')
num_views = models.PositiveIntegerField(editable = False, default=0)
position = models.ForeignKey(PhotoPosition)
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
content_object = generic.GenericForeignKey('content_type', 'object_id')
class IKOptions:
spec_module = 'vehicles.specs'
cache_dir = 'photos'
image_field = 'original_image'
save_count_as = 'num_views'
class Vehicle(models.Model):
objects = VehicleManager()
stock_number = models.CharField(max_length=6, blank=False, unique=True)
vin = models.CharField(max_length=17, blank=False)
....
images = generic.GenericRelation('Photo', blank=True, null=True)
Progress Update
I've tried out the code, and while it works, I'm missing something as I can get the image, but after that, they aren't transferred into the site_media/photos directory...am I suppossed to do this or imagekit will do this automatically? I'm a bit confused.
I'm saving the photos like so:
Photo.objects.create(content_object = vehicle, object_id = vehicle.id,
original_image = file)

Answer 1

My advice is running django script in a crontab job, lets say, 5 in 5 minutes.
The script would dive into the image folders and compare the images with the records.
A simplified example:
# Set up the Django Enviroment
from django.core.management import setup_environ
import settings
setup_environ(settings)
import os
from your_project.your_app.models import *
from datetime import datetime
vehicles_root = '/home/vehicles'
for stock_number in os.listdir(vehicles_root):
cur_path = vehicles_root+'/'+stock_number
if not os.path.isdir(cur_path):
continue # skip non dirs
for file in os.listdir(cur_path):
if not isfile(cur_path+'/'+file):
continue # skip non file
ext = file.split('.')[-1]
if ext.lower() not in ('png','gif','jpg',):
continue # skip non image
last_mod = os.stat(cur_path+'/'+file).st_mtime
v = Vehicle.objects.get(stock_number=stock_number)
if v.last_upd < datetime.fromtimestamp(last_mod):
# do your magic here, move image, etc.
v.last_upd = datetime.now()
v.save()