Ggtcf

I've built a function to control the upvotes and downvotes on replies. Exactly like it works on SO.

It works perfectly fins - almost.

If I call it once (by clicking upvote or downvote), it is completely fine, but if I call it again (set it to 0 from -1 or 1), it starts running forever bouncing through -1, 0 and 1 (I am the only user so it doesn't get beyond 1 vote).

I can't understand what is causing this behavior. I'm thinking maybe it has something to do with the fact that it is inside a listener so the value change keeps igniting the function? If that's the case, how do I get the value I need without a listener? I'm not sure.. Help?

 private fun executeVote(vote: String) 


 val refVotes = FirebaseDatabase.getInstance().getReference("/votes/$answerId")
 refVotes.addValueEventListener(object : ValueEventListener 
 override fun onCancelled(p0: DatabaseError) 

 

 override fun onDataChange(p0: DataSnapshot) 
 val refUserVote = FirebaseDatabase.getInstance().getReference("/votes/$answerId/$uid")

 if (p0.hasChild("$uid")) 
 var voteValue = 0
 refUserVote.addListenerForSingleValueEvent(object : ValueEventListener 
 override fun onCancelled(p0: DatabaseError) 

 

 override fun onDataChange(p0: DataSnapshot) 
 voteValue = p0.getValue().toString().toInt()

 when (voteValue) 

 1 -> 
 when (vote) 
 "up" -> refUserVote.setValue(1)
 "down" -> refUserVote.setValue(0)
 else -> refUserVote.setValue(0)
 
 

 0 -> 
 when (vote) 
 "up" -> refUserVote.setValue(1)
 "down" -> refUserVote.setValue(-1)
 else -> refUserVote.setValue(0)

 
 

 -1 -> 
 when (vote) 
 "up" -> refUserVote.setValue(0)
 "down" -> refUserVote.setValue(-1)
 else -> refUserVote.setValue(0)

 
 
 

 

 )


 else 
 when (vote) 
 "up" -> refUserVote.setValue(1)
 "down" -> refUserVote.setValue(-1)
 else -> refUserVote.setValue(0)
 
 
 


 )

 

It makes sense because when you're calling setValue, the onDataChange will be called again, even though you are calling it from that same function.

When you're about to call setValue, remove the listener, call setValue, add the listener again (this is a typical Java way).

I would also avoid doing something in the else conditions, it's unneccessarily triggering events.

My problem was in using addValueEventListener instead of addListenerForSingleValueEvent which I woudl assume as implied by name would listen once and let go.