Валидация для текущего пользователя

Как реализовать проверку 'name' для текущего пользователя в forms.py в ValidationError('Same name already added, change name').

views.py

@login_required
def main_page(request):
form = URL_listForm(request.POST)
if request.method == "POST":
    if form.is_valid():
        name = form.cleaned_data['name']
        if URL_list.objects.filter(user=request.user, name=name).exists():
            return HttpResponse('Same name already added, change name')
        new_post = form.save(commit=False)
        new_post.user = request.user
        new_post.save()
        return HttpResponse("Data added")
return render(request, 'link/main.html', {'form': form})

 #-------ADDED CODE
 data_tmp = """SELECT count(*) from jobtest WHERE link = %s""", (line)
 data_tmp = cur.fetchall()
 #-------END ADDED CODE

 if (data_tmp == 0 ) :
        Not exist