A Sydney man who assaulted his pregnant partner while live streaming a video game has escaped a jail term after claiming he acted in "excessive self defence".

Key points: The judge rebuked Luke Munday's legal team for characterising the assault as "just" a slap

The judge rebuked Luke Munday's legal team for characterising the assault as "just" a slap The court heard the former Telstra engineer had been fired after the incident

The court heard the former Telstra engineer had been fired after the incident The judge said his behaviour was "unlawful and violent"

Luke Munday, 27, was on Wednesday handed a 14-month community corrections order after admitting he slapped his then-partner in the face at an Oran Park home in December when she asked him to stop playing Fortnite.

His lawyer, Steven Mercael, earned a sharp rebuke in Picton Local Court from the magistrate after arguing for a lenient punishment.

"He's a loving, caring person with no history of domestic violence … who unfortunately on this day just slapped his partner," Mr Mercael said.

Mr Mercael withdrew the word "just" when Magistrate Mark Douglass warned the submission was "unwise", later declaring the court would not in any way accept that argument.

Munday was charged with common assault after viewers on the streaming platform Twitch witnessed the tense lead-up to the attack, during which his ex-partner threw objects at him.

Mr Mercael argued the former Telstra network engineer was acting in "excessive self defence" and said Munday was himself was a victim of domestic violence whose frustration lead him to snap.

The actual assault occurred out-of-frame of the video, but viewers heard a slapping noise before the woman said she was hit in the face.

Mr Douglass recorded a conviction and imposed a good behaviour condition as part of the sentence, noting the assault was witnessed by two children.

"There's no need to do great research to find that children who witness domestic violence struggle. It has a real impact on them," he said.

The magistrate said having objects thrown at him was not acceptable but Munday's impulse control and reaction was poor.

"The response was not appropriate, unlawful and violent," he said.

Luke Munday (left) and his lawyer Steven Mercael arrive at court. ( AAP: Bianca De Marchi )

The court heard Munday lost his job and was finding difficulty finding a new one because of media coverage of his court case.

Mr Mercael said his client was remorseful and had continued to pay for the accommodation of the former partner and children.

"He's disgusted with his behaviour, he's ashamed of his behaviour," Mr Mercael said.

"It was irresponsible behaviour.

"He takes complete responsibility for what occurred on that day."

He said Munday had been subjected to significant extra-curial punishment, including widespread public condemnation of the incident.

"He sobbed and wept when he saw messages of abuse from the general public," he said.