A 47-year-old man was taken to hospital after he was assaulted in Market Street, Wellingborough.
The incident happened at about 6.50pm on Wednesday, July 31.
Witnesses said the victim was laying on the floor next to the benches outside Costa Coffee, with blood on his head.
He was taken to Northampton General Hospital, where he is still being treated. But he is not thought to have any serious injuries.
A 21-year-old man was arrested in connection with the incident and he is still in custody this morning (Thursday).