How do I add fields on Reporting API Custom viewTemplate?

Follow these steps:

1. Create a custom viewTemplate.
2. Patch the custom viewTemplate by calling this API endpoint:
   
   POST /procurement-reporting-view/v2/prod/viewTemplates/nameofCustomViewTemplate/patch?realm=RealmName
   
   On the body part, specify: (note the real field example mixed in the code)
   
   {
   "selectAttributes": [
   "Attributes1",
   "Attributes2",
   "Attributes3",
   "cus_Attributes1",
   "cus_Attributes2",
   "StartDate",
   "UniqueId"
   ],
   "filterExpressions": [
   {
   "name": "FilterName",
   "field": "filterExpression1",
   "op": ">=",
   "defaultValue": "YYYY-MM-DDTHH:MI:SSZ"
   },
   {
   "name": "createdDateTo",
   "field": "TimeCreated",
   "op": "<=",
   "defaultValue": "2019-05-31T00:00:00Z"
   },
   {
   "name": "StatusInList",
   "field": "StatusString",
   "op": "IN",
   "defaultValue": [
   "Submitted"
   ]
   }
   ]
   }

1. Only the custom viewTemplate can be modified/patched. The system viewTemplate cannot be modified.
2. Invoke the GET /metadata API end point to bring back the available Select Fields and Filter Expressions.
3. Notice that on custom view, duplicate fields are not allowed.

Core Procurement > Procurement REST APIs > Operational Reporting API
SAP Ariba Analysis Reporting > Analytical Reporting - REST API
Strategic Sourcing > Strategic Sourcing - REST API > Strategic Sourcing - Operational Reporting API