Make Seeded Field Read only using value present in DFF

Make Seeded Field Read only using value present in DFF

We have a requirement to make the Quantity Field non editable based on below two conditions

1. When PO Line has a Requisition Backup/Reference
2. When it is a converted PO (We are using one PO Line DFF in all converted PO)

It should allow to update the quantity if we add new line on existing PO which does not have requisition back and vice versa.

To Achieve this requirement, we are trying to write below script using sandbox customization on quantity field.

#{row.Requisition != null or empty bindings.AttributeXYZ.inputValue}