D365 F&O: Set form datasource fields as mandatory via extension

VendTableAVG_Extension.xml

[ExtensionOf(formStr(VendTable))]
final class VendTableAVG_Extension
{
    void init()
    {
        next init();

        this.setMandatoryFields();
    }

    void setMandatoryFields()
    {
        FormDataSource dataSource = VendTable_ds;
        
        // Buyer group
        dataSource.object(fieldName2id(dataSource.table(),
            formDataFieldStr(VendTable, VendTable, ItemBuyerGroupId)))
            .mandatory(true);
        
        // Other Option
        // Segment
        dataSource.object(fieldNum(VendTable,  SegmentId)).mandatory(true);

        // Terms of payment
        dataSource.object(fieldNum(VendTable,  PaymTermId)).mandatory(true);
    }
}