Locals 'fed up' after one-punch attack at popular Adelaide nightspot

A one-punch attack at a popular Adelaide party strip has locals demanding more protection from police.

A 23-year-old man from Happy Valley was knocked unconscious in Moseley Square, Glenelg, about 2am today.

He was taken to Flinders Medical Centre with non-life-threatening injuries, but anti-violence activists said it was a lucky escape.

"Unfortunately we're getting asked for comment on these things a bit too much," Sammy D Foundation general manager Brigid Koenig told 9News.

"We know the consequences of violence and they can be fatal."

The Sammy D Foundation was formed in memory of teenager Sam Davis, who was killed in a one-punch attack in 2008.

Police arrested a man over this morning's attack a few hundred metres from the scene.

The 37-year-old, from Morphett Vale, was charged with assault causing harm and will face court in January.

Glenelg has had numerous incidents of violence recently, including a fight in the middle of Jetty Road a month ago.

Two men were randomly attacked on the same road in June.

Local residents say they're fed up.

"I definitely think there's not as much police presence down at Glenelg (as) there is in the city, and I think it might be something they can work on," one resident said.