Prefetching image renditions

[mrques...@gmail.com]

Is it possible to prefetch image renditions? I have a index page with a lot of images, which issues a query for every image.

[Salvador Faria]

I have been trying to minimize queries related to image thumbnails and you can do something like this:

- prefetch all image renditions

- use lru cache to 'cache' the most used images renditions

I have not completed my optimizations and code cleanup, but it is like I was playing around.

@lru_cache(maxsize=200)
def get_image_renditions(image):
    return image.renditions.all().select_related('filter')


def get_rendition(image, filter_spec):
    renditions = get_image_renditions(image)
    for r in renditions:
        if r.filter.spec == filter_spec:
            return r
    return image.get_rendition(filter_spec)

@register.assignment_tag
def image_rendition(image, filter_spec):
    return get_rendition(image, filter_spec)

# using a templatetag as "wrapper"

{% image_rendition post.author.profile_picture fill-270x270 as avatar_image %}

[mrques...@gmail.com]

Thanks for the tip!

It'd be cool to have something like this built-in, as this is such a common use case.