Motor moving by degree amounts with a button

[BenGrapevine]

Hey,

Just a quick question regarding joystick buttons:

How would I make a joystick button so that when it is pressed once it moves a motor in a degree amount (e.g. 45*), then stops?

[ignore if you don't care about why]
We have a door that holds the basketballs from getting into the shooter, (which when the door moves (in a 360* fashion if that makes sense) it lets one ball through) and moving it in increments would be so much easier.
[/ignore]

I can make a motor that is controlled by a trigger where the motor stops when you release it, so I have some exposure to buttons but yeah.

Thanks guys,
Tony

p.s. I've done my research and I haven't really found anything that works.