Question

Setup

I have a Master-Detail relationship, and on the master, I sum up a field from the Detail object.

Question:

I need to allow the user to check a box on the master object which will add the sum by 1 or decrement by 1. How do I do this?

Here’s what I’ve tried:

1. In an after update trigger on the master increment/decrement within the trigger. Of course I get an error:

   expected exception, contact your administrator: NonCashCompAfterUpdate: execution of
   AfterUpdate caused by:

2. Created a new field, and used the existing field as a helper. Basically, I’ve hidden the old RFS while still using it. This works, but I wanted to see if there was a better way.

Before I went any further I wanted to check in for ideas.

Thanks!

Answer 1

There is no way to directly alter values on a roll-up summary field in salesforce, except by altering the underlying detail records. The second proposal, as I understand it, would involve three fields, the roll-up summary, the checkbox, and the displayed summary (which would be a formula field). The displayed summary field would look something like this:

Rollup_Summary_Field__c + IF(Checkbox_Field__c, 1, -1)

The read-only nature of a roll-up summary field is preserved in Apex as well, so you would not be able to alter it through a trigger. Presumably, that is the nature of the error that you got, though the excerpt that you have attached omits the actual error.