django-images

Unlike other popular thumbnailing solutions, this one keeps information about existing thumbnails in the database. This is crucial for external storages where checking for file's existence can either cost significant amounts of time or money (think Amazon S3).

We've decided to only generate thumbnails on demand. When requesting an URL for a thumbnail that does not yet exist, you will receive an URL to a view that actually generates the thumbnail and then redirects the browser to the proper URL.

We also force you to define all thumbnail options in Django settings so you don't accidentally end up with hundreds copies of the same image in 300×300, 303×301, 301×305 just because the template author was too lazy to check the other places.

Installation

You can install django-images using pip:

$ pip install django-images

Remember to add it to your project's INSTALLED_APPS:

# settings.py
INSTALLED_APPS = [
    ...,
    'django_images',
    ...
]

And to your urls.py:

# urls.py
urlpatterns = patterns(
    '',
    ...,
    url(r'^images/', include('django_images.urls')),
    ...
)

Models

We supply an Image model that holds information about the image.

# models.py
from django.db import models
from django_images.models import Image


class Product(models.Model):
    pass


class ProductImage(Image):

    product = models.ForeignKey(Product, related_name='images')

Settings

IMAGE_SIZES controls the sizes and options:

# settings.py
IMAGE_SIZES = {
    'normal': {
        'size': (500, 0),
        'quality': 85
    },
    'tiny_square': {
        'size': (100, 100),
        'crop': True
    }
}

Possible params are size (tuple of (width, height), zero as either means unrestricted), crop (defaults to False), upscale (defaults to False) and quality (default is None, uses whatever input image's quality was).

IMAGE_PATH controls the upload path of both images and thumbnails. The default implementation will use paths like:

image/original/by-md5/7/d/7d7561de541093c04bb89c33468e88c0/file.jpg

You can override it by defining a function that accepts the model and original filename and returns the path to use, as you would use with Django FileField's upload_to parameter. The main difference is that the same function will be called for both original images and thumbnails:

from django_images.models import Image

def my_image_path(instance, filename):
    if isinstance(instance, Image):
        return 'original/%s' % (filename,)
    else:
        return 'thumbnail/%s/%s' % (instance.size, filename)

IMAGE_PATH = my_image_path

You can also choose to define your custom function in another module and set IMAGE_PATH to its location:

IMAGE_PATH = 'my_package.my_module.my_function_name'

IMAGE_AUTO_DELETE controls deletion of files from the storage. Django doesn't delete these files by default, but we do.

Templates

{% load at_size from images %}

{% for image in product.images.all %}
    <img src="{{ image|at_size:"tiny_square" }}" alt="">
{% endfor %}

Updating from django-images <= 0.3

The database schema has been changed in 0.4 release. To accomodate existing installations south migrations have been provided.

When updating an existing installation to 0.4, migrations have to be synced with database. It can be done by doing:

$ ./manage.py migrate django_images 0001 --fake
$ ./manage.py migrate django_images

mirumee / django-images