How populate a Read Only Grid using a ER

Question

Hello 
 I need to create a summary I have two sections, one of them with date information In the other one I need to use a Read Only Grid, to show I created a ER. to return data using an Id, but I don`t know how used the ER, in the Read Only Grid. I don't know what to put in the expression field 
 
 Someone could you help me please? 
 Best regards

Peter Lewis · Accepted Answer

Thanks for the detailed explanation! There's actually an easier way to do this if you want to display record data in a grid. Instead of creating a separate expression rule, you can set the source of your grid to be a record type. Then, you can use any of the fields in your columns (including related data). 
 The other thing to keep in mind is that in your section for configuring inputs, you need to define which record ID is going to return items for the grid. If you're showing this on a record summary view, you likely don't want this to always be the same value - instead, you want it to change based on which record view you're looking at. In order to configure that, your expReqId should reference a rule input in your interface so you can dynamically pass the results of your record.