title: Firebase search child and return parent key
body: <p>I am trying to return the UID key value in Firebase from a search on its child parameters.</p>
  
  <pre><code>-Users
  
   -BCsuC4XAZq0MDK1taLcD2
        -Name: Test1
        -Phone:  0011223344
  
  
   -t50GPKxb8mgINGbmGJrR83
        -Name: Test2
        -Phone: 9988776655
  </code></pre>
  
  <p>So from this database above, I am trying to implement a search function based on the phone number, where a user searching for "9988776655" will get the return value of "t50GPKxb8mgINGbmGJrR83", but after hours of messing about I am no closer to being able to do this.</p>
  
  <p>There is a post here:
  <a href="https://stackoverflow.com/questions/43618268/query-firebase-based-on-field-and-return-parent-in-android">Query Firebase based on field and return parent in Android</a><br>
  That looks like it would be pretty close, but unfortunately the full solution code is not offered.  After dabbling around with it, the best I can get trying to fit it into my scenario is a null response.</p>
  
  <p>Does anyone have any idea how I can actually do this?   I have read dozens of forum posts, and watched several youtube tutorials but no one seems to be able to do this.   Is it possible?</p>