jQuery Grid Plugin - jqGrid

hi, all
Can somebody explain me: which string`s format I must use in order to 
construct select element in jqGrid if I use function ? Quote from 
documentation: "When defined as function - the function should return 
either formated string or object."

i.e. in colModel I have
 { 
name:'ContactType',index:'ContactType',...,editable:true,edittype:"select",editoptions:{value:getContactTypeTA()},...}
and function definition is next

function getContactTypeTA()
{ return "{1:"Type1",2:"Type2"}";}

In this example function return "either formated" string - and that's 
really so: {1:"Type1",2:"Type2"}. BUT !!! In jqGrind that's don' work.
Where can I find format for "either formated string" ?
Any suggestion?

Method supposed here 
http://geekswithblogs.net/renso/archive/2009/07/02/jqgrid-dynamically-loading-select-options.aspx

don't work too.

P.S. It is necessary use scheme without php (editoptions: { size: 
1,dataUrl: 'Includes/tblJobSelect.php',...}), because it use GET and I'm 
use POST.