useFieldArray

[bidivale]

I am still in learning stage of coding. I have 2 basic requirements that I cannot perform using useFieldArray.
My useFieldArray name is invoiceItems. And each of my fields will contain the following input fields - productName, productCode, unitPrice, quantity, lineTotal.

1st requirement - The value of lineTotal will be unitPrice*quantity. I do not know what is the correct way to do that. I have done similar thing using setValue inside an useffect and keeping the required input value (using watch ) as a dependency of that useEffect. But here I cannot access the value of unitPrice or quantity individually without mapping the whole array. And useEffect does not work inside map.

2nd requirement - I want the values of productcode and unitPrice to auto-populate following the value of productName. But outside the fields.map(), is there any way to know which field is currently taking input inside fields.map() ?