How to set the current user on the model instance using newforms admin.

from django.db import models
from django.http import Http404, HttpResponse, HttpResponseRedirect
from django.utils.html import escape
from django.utils.safestring import mark_safe
from django.db import models, transaction
from django.contrib.auth.models import User
from django.utils.encoding import force_unicode
from django.utils.translation import ugettext as _

class Post(models.Model):
    user = models.ForeignKey(User)
    content = models.TextField()

from django.contrib import admin

class PostModelAdmin(admin.ModelAdmin):

    fields= ('content',)

    def __call__(self, request, url):
        self.user = request.user
        return super(PostModelAdmin, self).__call__(request, url)

    def save_add(self, request, model, form, formsets, post_url_continue):
        """
        Saves the object in the "add" stage and returns an HttpResponseRedirect.

        `form` is a bound Form instance that's verified to be valid.
        """
        from django.contrib.admin.models import LogEntry, ADDITION
        from django.contrib.contenttypes.models import ContentType
        opts = model._meta
        new_object = form.save(commit=False)
        new_object.user = self.user
        new_object.save()
        form.save_m2m()

        if formsets:
            for formset in formsets:
                # HACK: it seems like the parent obejct should be passed into
                # a method of something, not just set as an attribute
                formset.instance = new_object
                formset.save()

        pk_value = new_object._get_pk_val()
        LogEntry.objects.log_action(request.user.id, ContentType.objects.get_for_model(model).id, pk_value, force_unicode(new_object), ADDITION)
        msg = _('The %(name)s "%(obj)s" was added successfully.') % {'name': opts.verbose_name, 'obj': new_object}
        # Here, we distinguish between different save types by checking for
        # the presence of keys in request.POST.
        if request.POST.has_key("_continue"):
            request.user.message_set.create(message=msg + ' ' + _("You may edit it again below."))
            if request.POST.has_key("_popup"):
                post_url_continue += "?_popup=1"
            return HttpResponseRedirect(post_url_continue % pk_value)
        if request.POST.has_key("_popup"):
            return HttpResponse('<script type="text/javascript">opener.dismissAddAnotherPopup(window, "%s", "%s");</script>' % \
                # escape() calls force_unicode.
                (escape(pk_value), escape(new_object)))
        elif request.POST.has_key("_addanother"):
            request.user.message_set.create(message=msg + ' ' + (_("You may add another %s below.") % opts.verbose_name))
            return HttpResponseRedirect(request.path)
        else:
            request.user.message_set.create(message=msg)
            # Figure out where to redirect. If the user has change permission,
            # redirect to the change-list page for this object. Otherwise,
            # redirect to the admin index.
            if self.has_change_permission(request, None):
                post_url = '../'
            else:
                post_url = '../../../'
            return HttpResponseRedirect(post_url)
    save_add = transaction.commit_on_success(save_add)

    def save_change(self, request, model, form, formsets=None):
        """
        Saves the object in the "change" stage and returns an HttpResponseRedirect.

        `form` is a bound Form instance that's verified to be valid.

        `formsets` is a sequence of InlineFormSet instances that are verified to be valid.
        """
        from django.contrib.admin.models import LogEntry, CHANGE
        from django.contrib.contenttypes.models import ContentType
        opts = model._meta
        new_object = form.save(commit=False)
        new_object.user = self.user
        new_object.save()
        form.save_m2m()
        pk_value = new_object._get_pk_val()

        if formsets:
            for formset in formsets:
                formset.save()

        # Construct the change message. TODO: Temporarily commented-out,
        # as manipulator object doesn't exist anymore, and we don't yet
        # have a way to get fields_added, fields_changed, fields_deleted.
        change_message = []
        #if manipulator.fields_added:
            #change_message.append(_('Added %s.') % get_text_list(manipulator.fields_added, _('and')))
        #if manipulator.fields_changed:
            #change_message.append(_('Changed %s.') % get_text_list(manipulator.fields_changed, _('and')))
        #if manipulator.fields_deleted:
            #change_message.append(_('Deleted %s.') % get_text_list(manipulator.fields_deleted, _('and')))
        #change_message = ' '.join(change_message)
        if not change_message:
            change_message = _('No fields changed.')
        LogEntry.objects.log_action(request.user.id, ContentType.objects.get_for_model(model).id, pk_value, force_unicode(new_object), CHANGE, change_message)

        msg = _('The %(name)s "%(obj)s" was changed successfully.') % {'name': opts.verbose_name, 'obj': new_object}
        if request.POST.has_key("_continue"):
            request.user.message_set.create(message=msg + ' ' + _("You may edit it again below."))
            if request.REQUEST.has_key('_popup'):
                return HttpResponseRedirect(request.path + "?_popup=1")
            else:
                return HttpResponseRedirect(request.path)
        elif request.POST.has_key("_saveasnew"):
            request.user.message_set.create(message=_('The %(name)s "%(obj)s" was added successfully. You may edit it again below.') % {'name': opts.verbose_name, 'obj': new_object})
            return HttpResponseRedirect("../%s/" % pk_value)
        elif request.POST.has_key("_addanother"):
            request.user.message_set.create(message=msg + ' ' + (_("You may add another %s below.") % opts.verbose_name))
            return HttpResponseRedirect("../add/")
        else:
            request.user.message_set.create(message=msg)
            return HttpResponseRedirect("../")
    save_change = transaction.commit_on_success(save_change)

admin.site.register(Post, PostModelAdmin)