I don't think there's an "official" dress code but you definitely don't want to go there in nasty jeans or shorts...a tux isn't necessary either. I'd call it business casual or better.
Casual attire or dress up both are fine. No shorts please.
No dress code just show up with money.
If you are going out to eat at a restaurant other than a chain establishment, show some respect and dress business casual at the very least.
Thanks! Your answer is awaiting moderation.