Weird behavior in script

[Sanjay Rallapal]

Xanadu

I have script that is called in the Service Catalog Item Workflow post approval. It is trivial

var details = "Requested Item Details:\n";

// Get the current request item

var grReqItem = new GlideRecord('sc_req_item');

grReqItem.get(current.sys_id);

// Get the corresponding catalog item

var grCatItem = new GlideRecord('sc_cat_item');

grCatItem.get(grReqItem.cat_item);

// 2. Query approvals related to this RITM (sc_req_item) record

var approvalGR = new GlideRecord('sysapproval_approver');

approvalGR.addQuery('sysapproval', current.sys_id);

approvalGR.query();

Next it creates a JSON payload 

var payload = {

"requester": current.opened_by.getDisplayValue(),

"approver": approvalGR.approver.getDisplayValue(),

"approverComments": "",

"approvalDate": "2025-01-01",

"itemId": grCatItem.sys_id,

"External Catalog ID": grCatItem.u_external_catalog_id // custom attribute defined in the sc_cat_item table

};

Issue:
When I print the payload using gs.log(JSON.stringify(payload),"RITM Debug"); External Catalog ID is null. 
But, if I print just the value gs.log("External Catalog ID" + grCatItem.u_external_catalog_id,"RITM Debug");
the value is logged.

What am I doing wrong?

[Sanjay Rallapal]

Hello all,

Thank you for you suggestions. I tried all of them and wanted to report back

1. I couldn't append a double quote because that would mean altering the value of the attribute

2. I used the getvalue approach suggested by @Sandeep Rajput 
3. I also. tried the current.cat_item... approach suggested by @Ankur Bawiskar 

Approach (2) and (3) returned a value but that worked only when string concatenation was done.
In both approaches, I had to append toString() to get the payload to be constructed correctly. I don't know the technical rationale. I found this out by trial and error.
Follow up to above: I tried @SanjivMeher suggestion of appending "" (double quotes without a space) and that worked. It seems to have the same effect as toString()