The police summary of facts said Newman was on Amohia St on April 18 about 6pm with her two children, aged 9 and 4.
They were waiting to cross the road after Newman had just withdrawn $300 from an ATM outside the ASB bank.
Harris, who had been inside Central Mall, followed Newman out and stood directly behind her.
He grabbed her handbag using such force it caused her to fall back and hit her head on the concrete footpath.
Newman suffered grazing and cuts to her arms and legs, and dizzy spells after hitting her head on the concrete.
Harris told police he tried to get the money because an associate told him to.
Six days later, on Monday, April 24 at 4.45pm, Harris saw a silver Toyota car parked outside a dairy on Pererika St.
The driver of the car had gone into the dairy, leaving her 2-year-old in the rear passenger seat. She forgot to remove the keys from the vehicle's ignition, the summary said.
Harris got into the car and drove it away at speed, but didn't initially realise there was a child in the car.
About 1km down the road, he heard the child crying in the backseat. Harris parked the car down a side street, threw the keys on a grass verge and ran away.
The summary said he didn't attempt to notify police or anyone else there was a child in the vehicle unattended.
The vehicle was found an hour later by a member of the public and they called police.
The child was distressed but not hurt.
Judge Wilson said he had received a letter of remorse from Harris, but concluded his remorse was not "extraordinary".
He said the abandonment of a child charge - the most serious Harris faced - was "unusual" because he never intended for it to be a kidnapping.
"The real issue is that you should have put the child's interest ahead of your own when you realised the child was there, but you didn't.
"The child was uninjured but the mother came back to see she had no car and more importantly no child, which was a deeply traumatic experience for her."
Harris grasped the hand of one of his supporters over the glass partition separating the public gallery before leaving the courtroom after he was sentenced.
Speaking to the Rotorua Daily Post, Fraser Newman said he and his wife were "absolutely livid" about Harris' sentence.
"We are going to have to explain to our children that the justice system has failed us," he said.
"We feel like the law has worked in his favour, not ours."
Newman said his family did not go out at night and his wife had become very protective of their children since the attack. He believed there would be a lasting impact on his children having witnessed Harris' actions.