How can I set the value for columns in interactive grid before Insert its hidden items and I need to set the value automatically before insert .

I created process and set the following values

:HOSPITAL_NO := :P0_HOSPITAL_NO;
:CREATING_DATE := SYSDATE;
:CREATING_USER := :P0_USERNAME;
:USER_ID := :P33_USERNAME;

I put the process first one in the processes before Save interactive grid data process
but when I click on save button it show error

ORA-01400: cannot insert NULL into ("A244864"."SYS_CLINIC_USERS"."HOSPITAL_NO")

Is this way correct to set the columns value ?