title: Query PFUser currentUser for a custom field
body: <p>I am using the parse framework and would like to know how I can query a column that is located in the PFUser table. </p>
  
  <p>Here is some example code: </p>
  
  <pre><code>//Adds athlete_id column to roster table    
  PFObject *roster = [PFObject objectWithClassName:@"Roster"];
  roster[@"athlete_id"] = answer;
  [roster save];
  
  //Adds the rosters objectId to an array (athlete_id) in the User table. 
  PFUser *currentUser = [PFUser currentUser];
  [currentUser addObject:roster.objectId forKey:@"athlete_id"];
  [currentUser saveInBackground];
  </code></pre>
  
  <p>With the above code end up getting an array of objectsID's within the User class in a column named "athlete_id". </p>
  
  <p>Im having a problem actually retrieving this array from the User class. Here is how I am attempting to get the array from the user: </p>
  
  <pre><code>FQuery *query = [PFUser query];;
      [query whereKey:@"username" equalTo:[PFUser currentUser].username];
      [query whereKeyExists:@"athelete_id"];
      [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
          if (!error) {
  
              NSLog(@"athlete %@", objects);
  
          } else {
  
              NSLog(@"Error: %@ %@", error, [error userInfo]);
  
          }
      }];
  </code></pre>
  
  <p>I want to grab the array that is contained in athlete_id column for the current user, but the objects array is empty on this query. </p>