Generating an InlineModelAdmin Form on the fly in Django

I'm adding drag/drop uploading to the django admin for one of our open source projects called Stager. A blog post about that will follow, it's not screen-shot ready yet.  While doing this I knew we needed a pretty seamless transition after the upload finished, and that we would have to refresh the inline.  I didn't want a full page refresh, so let's ajax it in.

For these examples just assume that we have a parent CompAdmin which has an model of Comp and an inline called CompSlideInline.  We store the instance of the Comp in comp.

from django.template import loader, Context
from django.contrib.admin import helpers
from django.db import transaction
from django.contrib import admin

comp = Comp.objects.get(id=comp_id)
#get the current site
admin_site =
compAdmin = CompAdmin(Comp, admin_site)

#get all possible inlines for the parent Admin
inline_instances = compAdmin.get_inline_instances(request)
prefixes = {}

for FormSet, inline in zip(compAdmin.get_formsets(request, comp), inline_instances):
    #get the inline of interest and generate it's formset
    if isinstance(inline, CompSlideInline):
        prefix = FormSet.get_default_prefix()
        prefixes[prefix] = prefixes.get(prefix, 0) + 1
        if prefixes[prefix] != 1 or not prefix:
            prefix = "%s-%s" % (prefix, prefixes[prefix])
        formset = FormSet(instance=comp, prefix=prefix, queryset=inline.queryset(request))

#get possible fieldsets, readonly, and prepopulated information for the parent Admin
fieldsets = list(inline.get_fieldsets(request, comp))
readonly = list(inline.get_readonly_fields(request, comp))
prepopulated = dict(inline.get_prepopulated_fields(request, comp))

#generate the inline formset
inline_admin_formset = helpers.InlineAdminFormSet(inline, formset,
            fieldsets, prepopulated, readonly, model_admin=compAdmin)

#render the template
t = loader.get_template('tabular.html')
c = Context({ 'inline_admin_formset': inline_admin_formset })
rendered = t.render(c)