persist data in a DB issue, receiving NULL on console

I am new to NodeJS and I am having an issue trying to persist/save some data in a DB.

let's start from the beginning so you can understand easier. I have a list of sports with an option to checked or unchcked, that's what I need to persist, that checked.

FRONT END:

controller.js

$scope.toggleSportSelection = function(sport) {
  var params = {};
  params.user = $scope.customer.customer;
  sport.checked = !sport.checked;
  SportsFactory.setSportChecked(params);
};

service.js

  setSportChecked: function(params) {
    var defer = $q.defer();
    $http.post(CONSTANT_VARS.BACKEND_URL + '/sports/checked', params)
    .success(function(sportChecked) {
        LocalForageFactory.remove(CONSTANT_VARS.LOCALFORAGE_SPORTS_CHECKED, params);
        defer.resolve(sportChecked);
      })
      .error(function(err) {
        console.log(err);
        defer.reject(err);
      });
    return defer.promise;
  }

I've been debugging this front end part and everything seems to be OK...

Now BACK END:

setSportCtrl.js

module.exports = {

  setCheck: function(req, res) {
    var checkedSportParams = req.body;

    SportSelectionService.sportChecked(checkedSportParams).then(function() {
      res.json(200, {msg: 'OK'});
    }, function(err) {
      res.json(400, err);
    });
  }
}

SportSelection.js (model)

module.exports = {
  connection: 'capilleiraRedisServer',
  attributes: {
    sport: {
      type: 'array',
      required: false
    },

    user: {
      type: 'string',
      required: true
    }
  }
};

in this part I can see how that console are print in the terminal, but if I do console.log(sportChecked) or console.log(newSport) all I get is an array which says null everywhere...

SportSelectionService.js

module.exports = {

  sportChecked: function(params) {
    var Promise = require('bluebird');
    return new Promise(function(fullfill, reject) {
      console.time('sportChecked_findOne');
      SportSelection.findOne({
        user: params.user
      }).exec(function(err, sportChecked) {
        console.timeEnd('sportChecked_findOne');
        var newSport;
        if (err) {
          reject(new Error('Error finding user'));
          console.error(err);
        }else if (sportChecked) {
          newSport =  sportChecked.sport;
          console.time('sportChecked_update');
          SportSelection.update({
            user: params.user
          },
          {
            sport: newSport
          }).exec(function(err, sportCheckedUpdated) {
            console.timeEnd('sportChecked_update');
            if (err) {
              reject(new Error('Error on sportChecked'));
            }else {
              fullfill(sportCheckedUpdated);
            }
          });
          if (sportChecked.sport) {
            sportChecked.sport.push(params.sport);
            console.log('New sport added');
          }else {
            sportChecked.sport = [params.sport];
          }
        }else {
          console.time('sportChecked_create');
          SportSelection.create({
            sport: [params.sport],
            user: params.user
          }).exec(function(err, created) {
              console.timeEnd('sportChecked_create');
              if (err) {
                reject(new Error('Error on sportChecked'));
              }else {
                fullfill(created);
              }
            });
        }
      });
    });
  }

so what do you think is my issue here ? what am I doing wrong ?