Require Opportunity Products on Opportunity in Salesforce

The requirement is that the customer wants a way during Opportunity creation to require the Opportunity products being filled in.

Workflow would only help after the sav开发者_Python百科e, they want it to evaluate before the save. Validation would only work on the opportunity. I'm unsure if a trigger would work or not.

Any ideas?

I've found the answer to this in case anybody else needs to know how to provide this ability You can create this as a validation rule after all. The formula is below:

NOT(OR(ISNEW(),HasOpportunityLineItem))