[newforms-admin] - caching of sql query for inlines

See http://groups.google.com/group/django-developers/msg/28a8d0efadc1b079

I have these models:

from django.db import models

class Category(models.Model):
    name = models.CharField(max_length=255)

class Library(models.Model):
    name = models.CharField(max_length=255)
    
class Book(models.Model):
    name = models.CharField(max_length=255)
    category = models.ForeignKey(Category)
    library = models.ForeignKey(Library)
    

And I register them:

class BookInline(admin.TabularInline):
    model = Book
    extra = 10
    fields = 'name', 'category',

class LibraryOptions(admin.ModelAdmin):
    inlines = BookInline,

admin.site.register(Library, LibraryOptions)

I have ten rows for books in library add form. Each row needs its own sql query to get list of categories. I think that the query should be cached.

It is caching in one request, not between requests. New forms and new formsets are created in each request.

New patch added - the old one doesn't work after [6080].

The discussion about this one did not reach a consensus:

http://groups.google.com/group/django-developers/browse_thread/thread/7aaa8a5297e3c4d5

therefore I'm taking its triage stage back.

This ticket isn't critical to merge of newforms-admin. Tagging with nfa-someday. This functionality can be accomplished by the user, but I personally feel it needs to be in Django.

fixes the real problem. formsets are declarative like forms. 85% done, but attaching to get feedback.