Hi I want to populate dropdown field on my form dynamically.I am on appian 7.2

Hi Amit,
In your code sniplet you have not given id_attr and display_attr. You are fetching material code object from rule, but what field of that object you need show in dropdown that u need to specify using id_attr and display_attr.
e.g
example1:
FormAPI.populateDropdown("txtMaterialCode", ["getMaterialCodeMappingExpRule","Carton","No"],"code","code");
here i am assuming that code is the field in CDT.

example2

FormAPI.populateDropdown("dropdown6", ["GetBusinessOriginDetailsByOriginCode", FormAPI.getValue("dropdown5").id], "code", "description");

kindly refer the attached Advanced form utilities guide

AdvancedFormsAPI_v1.6.0.pdf

Hi Ajinkya Thanks for suggestion,
My expression rule is not returning an object but perticular field of an object.
In form API guidelines there is an option that if id and value of drop down remains same then id_attr and display_attr are optional.

stackoverflow.com/.../unable-to-get-property-options-of-undefined-or-null-reference

This link might help you

Hi Amit,
In which browser you are executing this script.

I am using ie9

Can you see if the attached example works for you? Simply run an instance of Cascade Dropdowns Non-CDTs, selecting a food category should populate the second dropdown. I tried to mimic a similar scenario as yours (expression rule that takes two inputs, the second ons is pretty much to mimic your scenario but is irrelevant for the example)

Cascade Dropdowns Non-CDTs.zip

Thank you so much Ajinkya and eduardo for your inputs on this issue.
We also tried things at our end to take it to closure.
We were able to solve this using

importScript('/plugins/servlet/FormsExt.js');
          var txtComponent=FormAPI.getValue("drpdwnComponent").id;
          FormAPI.evaluateServerSideExpression(function(fn) {
          debugger;
          window.FormAPI.updateDropdownValues("txtMaterialCode",fn,fn);
          },["getMaterialCodeMappingExpRule",txtComponent,"No"]);