django-url-renditions

django-url-renditions allows to define and render renditions from django url fields. This works also pretty well with django-s3direct fields.

It comes with a Graphene Query that enable renditions in your GraphQL schema.

Install

pip install django-url-renditions

Add url_renditions to your INSTALLED_APPS

Define your model

from django.db import models
from url_renditions.fields import FileUrlWithRenditions

# django-url-renditions comes with a simple image resizer method.
# Look at the implementation if you need something more specific
from url_renditions.resize_image import ResizeImage

class Track(models.Model):
    original_artwork = models.URLField()
    artwork = FileUrlWithRenditions(
        source='original_artwork',
        use_job_runner=True, #  if we want to queue the job with django_rq
        renditions={
            'small': ResizeImage('80x80'),
            'medium': ResizeImage('300x300'),
        }
    )

That way, when a Track model get created with an original_artwork, artwork will be automatically polulated with two renditions: small and medium.

To access them, use:

r = my_track.artwork.rendition_set.get(name='small')
print('url:', r.href, 'width:', r.width, 'height:', r.height)

Graphql with Graphene

Add url_renditions.graphql_schema.Query to your root query.

import graphene
import url_renditions.graphql_schema  # noqa

class Query(
        ...
        url_renditions.graphql_schema.Query,
        graphene.ObjectType):
    pass

schema = graphene.Schema(query=Query)

Then when you ask for

{
  track(id: "VHJhY2s6OA==") {
    artwork {
      renditions {
        medium {
          href
          width
          height
        }
      }
    }
  }
}

You get

{
  "data": {
    "track": {
      "artwork": {
        "renditions": {
          "medium": {
            "href": "https://images.unsplash.com/photo-1474314170901-f351b68f544f",
            "width": 300,
            "height": 300
          }
        }
      }
    }
  }
}