def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def draw(self, context):
        layout = self.layout

        layout.template_header()

        userpref = context.user_preferences

        layout.operator_context = 'EXEC_AREA'
        layout.operator("wm.save_userpref")

        layout.operator_context = 'INVOKE_DEFAULT'

        if userpref.active_section == 'INPUT':
            layout.operator("wm.keyconfig_import")
            layout.operator("wm.keyconfig_export")
        elif userpref.active_section == 'ADDONS':
            layout.operator("wm.addon_install", icon='FILESEL')
            layout.operator("wm.addon_refresh", icon='FILE_REFRESH')
            layout.menu("USERPREF_MT_addons_online_resources")
        elif userpref.active_section == 'THEMES':
            layout.operator("ui.reset_default_theme")
            layout.operator("wm.theme_install")