Sleep Troubles

When Joshua grew tall enough to open door knobs, we put door knob covers on some of them.  Among the places we used them was on the inside door knob in his room,so he wouldn't come out during naps and at night.  But soon he figured out how to defeat them through his brute strength.  Since then, we've mostly been okay, as he pretty much stays in his room if we tell him.  But there were a couple times where he was allowed to stay in our room overnight, and that apparently made him realize how much better he likes our room than his. For awhile, it was really difficult to put him to bed, as he would cry "Joshua want to sleep in Mama's room!!!"  We didn't give in, and he'd eventually relent and fall asleep in his room.  That's pretty much where we are now, but there's still the problem of what happens if he wakes up in the middle of the night.  When he wakes up, it's like he realizes he has a better option, so he'll come in our room and hop into our bed unbeknownst to us.  The last couple nights I've shut our door, thinking he might then just stay in his own room.  But tonight I was up late working on a project for work, and when I opened our door I saw where he had apparently wanted to come in our room, noticed the door was shut, and instead of going back in his own room, he decided to sleep by the door on the floor.  I'm not sure why this was a better option than going back to his own bed.  Hopefully we can get past this phase soon.