If you have ever used a inline in the admin for a model that contained
a model choice field you have probably noticed it has to query the
database for each row to fill the select drop-down. This results in n+
identical queries.
I though it might be useful to have a way to tell a admin inline to
cache the choices of fields. Here is some rough code that gets the job
done::
from django.forms.models import BaseInlineFormSet
class CachedInlineFormSet(BaseInlineFormSet):
cached_fields = []
def _construct_form(self, i, **kwargs):
form = super(CachedInlineFormSet, self)._construct_form(i,
**kwargs)
for cache_field in self.cached_fields:
field = form.fields[cache_field]
field.cache_choices = True
choices = getattr(self, '_cached_%s_choices' %
cache_field, None)
if choices is None:
choices = list(field.choices)
setattr(self, '_cached_%s_choices' % cache_field,
choices)
field.choice_cache = choices
return form
class CachedTabularInline(admin.TabularInline):
cached_fields = []
def get_formset(self, request, obj=None, **kwargs):
formset = super(CachedTabularInline,
self).get_formset(request, obj=None, **kwargs)
formset.cached_fields = self.cached_fields
return formset
class MyInline(CachedTabularInline):
model = MyModel
cache_fields = ['myfk']
Im not super big on how this patches the classes in various places so
i'm open to better suggestions. Is this something that the admin could
benefit from or is this better kept as a 3rd party tool?
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