Limit Meteor Vote Once Per Day

Question

I'm following the MeteorJS example for a leaderboard here: https://www.meteor.com/examples/leaderboard

I want to limit the votes to once per day (per IP address). What's the best way to do this?

Answer 1

The following solution assumes you are starting with a clean version of the leaderboard example.

Step one: Declare a new collection to hold IP address and date information. This can be added just below the definition of Players.

IPs = new Meteor.Collection('ips');

Step two: Replace the increment event with a call to our new method givePoints.

Template.leaderboard.events({
  'click input.inc': function() {
    var playerId = Session.get('selected_player');
    Meteor.call('givePoints', playerId, function(err) {
      if (err)
        alert(err.reason);
    });
  }
});

Step three: Define the givePoints method on the server (this.connection only works on the server). You can do this by inserting the following anywhere inside of the Meteor.isServer check or by creating a new file under the /server directory.

Meteor.methods({
  givePoints: function(playerId) {
    check(playerId, String);

    // we want to use a date with a 1-day granularity
    var startOfDay = new Date;
    startOfDay.setHours(0, 0, 0, 0);

    // the IP address of the caller
    ip = this.connection.clientAddress;

    // check by ip and date (these should be indexed)
    if (IPs.findOne({ip: ip, date: startOfDay})) {
      throw new Meteor.Error(403, 'You already voted!');
    } else {
      // the player has not voted yet
      Players.update(playerId, {$inc: {score: 5}});

      // make sure she cannot vote again today
      IPs.insert({ip: ip, date: startOfDay});
    }
  }
});

The complete code can be seen in this gist.