SAP PI message mapping remove null records

Hello experts,

I have a requirement in which we will receive a csv file . In this file some records of a particular value are null , so the requirement is to remove the entire records if the value is null .

Eg:

So Here I need to remove row1 and row3 completely as field 3 is null and transform only row2 with further mapping steps .

Please advise.

My source structure is

Records

field1

field2

field3