title: get array if array contains id mongoose
body: <p>It is a tricky one. I thought I could use $in, but after querying, it wasn't where I was looking for. </p>
  
  <p>This is my schema</p>
  
  <pre><code>var gameSchema = new mongoose.Schema({
      state: {
          type: String,
          default: "invited"
      },
      finished: {
          type: Boolean,
          default: false
      },
      players: {
          type: [{
              type: mongoose.Schema.Types.ObjectId,
              ref: 'users'
          }],
          required: true,
      },
      scores: [scoreSchema],
      chat : [chatSchema]
  });
  </code></pre>
  
  <p>The request I'm trying to make is the following, I send a user Id, if the players array contains this Id, return the other id (the array will always have length 2) in the array.</p>
  
  <p>The context is that you can lookup against whom you have played before.</p>
  
  <p>This is what I had, but "players" should be an array and it's not games that I want to return, so </p>
  
  <pre><code>exports.getFriends = function(id, cb){
      gameSchema.find({ id: { "$in": "players"} }, function(err, games){
          if(err){
              return cb(err, null);
          }
          else{
              return cb(null, games);
          }
      });
  };
  </code></pre>