Sort by existence of field

[StanLindsey]

I'm working on an e-commerce shop.

Currently, a categories default sorting is by descending price. 

The client doesn't have images for all products, wants the category sorted by products with images by default.

Easy:

sort=-image

This sorts by the filename, essentially alphabetically. 

I'd like to sort by those with images, with a secondary sort of price descending.

sort=-image, sort=price

This does not work, because the image sort is sorting alphabetically, not by the existence of the field. So you end up with this:

name     |     image    | price
product1 | product1.jpg | £12.34
product2 | product2.jpg | £43.43
product3 | product3.jpg | £12.20
product4 | product4.jpg | £76.20
product5 | product5.jpg | £12.50
product6 |     null     | £18.50
product7 |     null     | £16.21
product8 |     null     | £13.10

Notice that images prices are essentially ordered randomly, those with null image are ordered descending. 

So I need to have the selector sort by the existence of the image field, not by the content of the image field. 

I need to do this as part of the selector because some of these categories have 2000+ products and I cannot do it in-memory. 

Thoughts? 

 

[BitPoet]

Have you tried sorting by -image.count?

[StanLindsey]

Perfect - solved.

I didn't think of using the sub-selectors in the sort param for some reason.

[szabesz]

This reminds me that we have a recent discussion of "how to put count into good use":

https://weekly.pw/issue/248/ : "exact match queries using Page reference fields"