How to use the cartoview.app_manager.models.AppInstance.objects.filter function in cartoview

if len(author_form.cleaned_data['profile']) == 0:
                        # FIXME use form.add_error in django > 1.7
                        errors = author_form._errors.setdefault(
                            'profile', ErrorList())
                        errors.append(
                            _('You must set an author for this resource'))
                        metadata_author = None
                if author_form.has_changed and author_form.is_valid():
                    new_author = author_form.save()

            if new_poc is not None and new_author is not None:
                the_appinstance = appinstance_form.save()
                the_appinstance.poc = new_poc
                the_appinstance.metadata_author = new_author
                the_appinstance.keywords.add(*new_keywords)
                AppInstance.objects.filter(id=the_appinstance.id).update(
                    category=new_category)

                return HttpResponseRedirect(
                    reverse('appinstance_detail', args=(appinstance.id,)))
            else:
                the_appinstance = appinstance_form.save()
                if new_poc is None:
                    the_appinstance.poc = appinstance.owner
                if new_author is None:
                    the_appinstance.metadata_author = appinstance.owner
                the_appinstance.keywords.add(*new_keywords)
                AppInstance.objects.filter(id=the_appinstance.id).update(
                    category=new_category)

                return HttpResponseRedirect(
                    reverse('appinstance_detail', args=(appinstance.id,)))

documents = Document.objects.filter(title__icontains=title_filter)

        if settings.RESOURCE_PUBLISHING:
            documents = documents.filter(is_published=True)

        if not settings.SKIP_PERMS_FILTER:
            documents = documents.filter(id__in=authorized)

        counts = documents.values('doc_type').annotate(count=Count('doc_type'))
        facets = dict([(count['doc_type'], count['count']) for count in counts])

        return facets

    elif facet_type =='appinstances':
        appinstances= AppInstance.objects.filter(title__icontains=title_filter)
        if settings.RESOURCE_PUBLISHING:
            appinstances = appinstances.filter(is_published=True)

        if not settings.SKIP_PERMS_FILTER:
            appinstances = appinstances.filter(id__in=authorized)

        counts = appinstances.values('app__title').annotate(count=Count('app__name'))
        facets = dict([(count['app__title'], count['count']) for count in counts])
        return facets

    else:

        layers = Layer.objects.filter(title__icontains=title_filter)

        if settings.RESOURCE_PUBLISHING:
            layers = layers.filter(is_published=True)

the_appinstance.poc = new_poc
                the_appinstance.metadata_author = new_author
                the_appinstance.keywords.add(*new_keywords)
                AppInstance.objects.filter(id=the_appinstance.id).update(
                    category=new_category)

                return HttpResponseRedirect(
                    reverse('appinstance_detail', args=(appinstance.id,)))
            else:
                the_appinstance = appinstance_form.save()
                if new_poc is None:
                    the_appinstance.poc = appinstance.owner
                if new_author is None:
                    the_appinstance.metadata_author = appinstance.owner
                the_appinstance.keywords.add(*new_keywords)
                AppInstance.objects.filter(id=the_appinstance.id).update(
                    category=new_category)

                return HttpResponseRedirect(
                    reverse('appinstance_detail', args=(appinstance.id,)))

        if poc is not None:
            appinstance_form.fields['poc'].initial = poc.id
            poc_form = ProfileForm(prefix="poc")
            poc_form.hidden = True
        else:
            poc_form = ProfileForm(prefix="poc")
            poc_form.hidden = True
        if metadata_author is not None:
            appinstance_form.fields[
                'metadata_author'].initial = metadata_author.id
            author_form = ProfileForm(prefix="author")

def workspace(request):
    owner = request.user
    apps = AppInstance.objects.filter(owner=owner)
    created_apps = AppInstance.objects.all()
    layers = Layer.objects.filter(owner=owner)
    maps = Map.objects.filter(owner=owner)
    maps_count = Map.objects.all().count()
    layers_count = Layer.objects.all().count()
    documents = Document.objects.filter(owner=owner)
    documents_count = Document.objects.all().count()
    groups = owner.group_list_all()
    groups_count = GroupProfile.objects.all().count()
    return render(
        request,
        template_name='workspace/workspace.html',
        context={
            'my_apps': apps,
            'my_layers': layers,
            'created_apps': created_apps,