That's really really is a hack way about mongoose-random HOT 3 CLOSED

schema.statics.findRandom = function (query, callback) {
      var self = this;
      var coords = [randFn(), randFn()];

      if (typeof query === 'function') {
        callback = query;
        query = {};
      }

      query[path] = query[path] || {
        $near: {
          $geometry: { type: 'Point', coordinates: coords }
        }
      };

      return self.find(query); // notice here
    };

Tag.findRandom().exec(function(err, tag){
    console.log(err)
})

query['random'] = query['random'] || {
                             ^
TypeError: Cannot read property 'random' of undefined