The slashing occurred in the Craftsman Restaurant on Maple Avenue.
Officials say it was a minor domestic incident, and the woman accused of slashing the victim was with her four-year-old at the time.
The couple is said to have been arguing in a car at the time.
The victim suffered a slash to his arm, and needed 13 stitches.
It is unclear if the woman will face charges, police said.
The child was released into the care of his father.
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