The club has been in discussions with Longstaff for some time, with the midfielder’s deal set to expire at the end of the season.
Speaking last month, head coach Eddie Howe said: “Talks are continuing. He’s certainly someone that I have a lot of respect for, a lot of time for. I think he’s improved, even though he hasn’t played, and that hasn’t been shown to the general public, I think we’ve seen a real growth in his training performances.
"When he has played, I think he’s done very well, and he’s certainly someone we like and believe in, and I see a long term future for him here. I just hope we can get the contract sorted.”