ChangeList.get_queryset() automatically applies select_related() in a very "brute" way

[Béres Botond]

If there is a single related field from the listing model in list_display, ChangeList.get_queryset will apply select_related() so it will join everything, with no depth or field limitations.

Combined with the fact that there's no documented way to clear that (#16856), it's quite undesirable behaviour.

In my opinion this could be resolved in 2 ways:

1. Remove that .select_related() call altogether and let the developer choose the exact optimization if he is displaying related fields in the listing
2. Optimize the select_related() call so that it's constructed exactly based on which fields appear in list_display

[Julien Phalip]

Have you tried setting the ModelAdmin.list_select_related to False? Does it solve your problem?

[Julien Phalip]

Oh wait, never mind. The list_select_related attribute would in fact be ignored in your case.

I think your suggestion "2." would be too complex to implement and could be quite brittle.

I think "1." seems reasonable — it all depends if in most cases the developer would want to use select_related or not. It'd be good to provide a sane default that can be occasionally overridden. It'd be good to gather some anecdotal statistics on that. If it appears that using select_related would in fact be a sane default, then I'd rather focus on enabling the clearing of the select_related behavior (as discussed in #16856) for the time being.

Accepting this ticket on the basis that this is a valid issue that needs fixing.

[Tomek Paczkowski]

I've added pull request for this ticket: ​https://github.com/django/django/pull/1245

It implements finer control over select_related, allowing setting this attribute to a tuple. Empty tuple disables select_related and any other is passed as arguments to select_related.

[Tomek Paczkowski <tomek@…>]

In 0fd9f7c95f748764867dc148a2bacef807466d85:

Fixed #19080 -- Fine-grained control over select_related in admin

[Marc Tamlyn <marc.tamlyn@…>]

In 9ed971f4f1d2f05ecf7e2760556259eb2dca85f8:

Merge pull request #1245 from oinopion/list_select_related

Fixed #19080 -- Fine-grained control over select_related in admin

[Mariusz Felisiak <felisiak.mariusz@…>]

In 158eca4f:

Refs #19080 -- Added tests for preserving select_related() in the admin changelist.