title: Is there a way to catch what invoked value event listener
body: <p>Firebase data can be fetched by a single value event listener or a generalised value event listener. For my case I cannot use single value event listener. The problem is the listener gets triggered even when I do not want to. Let me explain the situation:</p>
  
  <p>I have a number of users in my database who are from a particular locality. The firebase database contains the users as the root and their profile details, along with their location (in Latitude and longitude) as the child nodes. </p>
  
  <p>Now as a simple case,  let's say a user wants to send a SOS for some emergency to other users located within a certain range. For that I perform some distance calculations between the user who is sending the SOS to all other users and make a list of other users who are present within a specified range. Then a notification is send to all these users. Here I use a value event listener to get the location details of the other users to compare with the location of the current user. My code runs as expected till this point. The value event listener is attached to the user node because I have to travel across the user details.</p>
  
  <p>Problem occurs when a user changes his profile details. It evokes the value event listener and the code takes some garbage value of the location of a user sending an SOS. As a result although there is no actual SOS sent, a notification is getting sent.</p>
  
  <p>Hope this explains the problem. I am not being able to provide the code as I am traveling and typing the code from my mobile. Can provide the code in some hours if it is necessary to guide on the problem.</p>