/* Main rule instead of a!gridTextColumn() */
a!applyComponents(
  function: rule!productCatOrDesc(
    productCategory: local!productCategory,
	productCategoryArray: index(local!products.data, "PRODUCT_CATEGORY", {}),
	productDescription: local!productDescription,
	productDescriptionArray: index(local!products.data, "PRODUCT_DESCRIPTION", {}),
	idx: _
  ),
  array: 1+enumerate(count(local!products.data))
)

/* Sub Rule Definition */
productCatOrDesc(	productCategory Number, 
					productCategoryArray Number (Multiple),
					productDescription Number,
					productDescriptionArray Number (Multiple),
					idx Number
				)
/* Sub Rule */
with(
  local!data: if(
    rule!APN_isBlank( /* assumes you have Appian common objects */
      ri!productDescritpionArray[ri!idx]
    ),
    rule!RADARR_ER_applyCategoryByCategoryID(
      productCategory: ri!productCategory,
      categoryID: ri!productCategoryArray[ri!idx]
    ),
    rule!RADARR_ER_applyDescriptionNameByDescriptionID(
      productDescription: ri!productDescription,
      descriptionID: ri!productDescriptionArray[ri!idx]
    )
  ),
  a!gridTextColumn(
    label: "Product",
    field: "PRODUCT_CATEGORY",
    data: local!data
  )
)