replace (-) or NULL for blank spaces

I have made a report say there are some fields where the values will be alphanumeric and hence forth these vaulues comes as blank in the report i am trying to replaces these blank spaces with - or NULL , AS far as numricALS are concerned we have a option in visual studio itself replace blank with - or null, how to do same for aphanumeric fields

Wouldn’t something like this work?


it is not working in my case i am using invoice id display method to get the invoiceid from vendinvoicejour and i have tried using expression mentioned above but the changes are not coming up here

If you are trying to amend this on display method, it won’t work. Display methods are non editable.

I have resolved the issue by writing the code to return the null value in the display like if invoice id is not there then it should return null value…