id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
10743	Support lookup separators in ModelAdmin.list_display	mrts	Tom Carrick	"As with #3400, supporting the `__` lookup separator in `ModelAdmin.list_display` is useful as it avoids calling `__unicode__` bluntly, giving users more control over the output:
 * display several fields from the same related model,
 * as listed in #3400, traverse several levels of relations.

One could argue that most of this can be achieved with `__unicode__` by cramming the information to its output.

However, there's a larger problem with deferred fields (deferring is exemplified in [http://code.djangoproject.com/ticket/10712#comment:3 this comment]) -- namely, that couples admin code to the implementation of `__unicode__` in related models. That is, knowledge of what fields are referred to in `__unicode__` is required to write proper deferred statements.

A case to illustrate how changes in `__unicode__` can have dramatic, unintentional impact:
 * assume the related objects are large and complex,
 * to keep the admin changelist view snappy, the developer looks which fields are referred to in their `__unicode__` and writes the `ModelAdmin.queryset()` method correspondingly, selecting only these fields with `only()`,
 * a single query is all that is needed to display the data in changelist view, admin is snappy, there is much rejoicing,
 * a second person keeps hacking at the related models, unknowing the impact changes to `__unicode__` could have to admin, adds another field to it,
 * suddenly rendering the changelist results in `n` queries, each of which pulls in the whole object.

All that can be avoided with explicit `__` support."	New feature	closed	contrib.admin	dev	Normal	fixed	efficient-admin, list_display	ales.zoulek@… zachborboa@… olivier.dalang@… Ofer Nave Adam Johnson Egor R Nina Menezes Tom Carrick	Ready for checkin	1	0	0	0	0	0