Expand the Documentation of Custom Lookups for V1.7

[Maarten]

Custom Lookups look great, however, I find the documentation terse. Example: no explanation what

lhs, lhs_params = self.process_lhs(qn, connection)

is exactly.

The explanation:

lhs
The lhs (left-hand side) of a lookup tells us what we are comparing the rhs to. It is an object which implements the query expression API. This is likely to be a field, an aggregate or a subclass of Transform.

does not explain what lhs_params might be. Also a search on process_lhs on complete Django website only points to this page (no other pages).

[Baptiste Mispelon]

I'll mark this ticket as accepted on the basis that there's probably some improvements to be made on this fairly new part of our documentation.

Are there other points beside the one you mentionned in the ticket that you think could be improved?

[Marc Tamlyn <marc.tamlyn@…>]

In 219d928852c256a81d09dbaa29ed4cec42d2fdfa:

Fixed #21863 -- supplemented get_lookup() with get_transform()

Also fixed #22124 -- Expanded explanation of exactly what is going on in
as_sql() methods.