gistfile1.js

module.exports = function () {
  var ObjectId = mongoose.Types.ObjectId;
  return function (req, res) {
    var type = capitalize(req.params.componentType);
    var id = new ObjectId(req.params.componentID);
    var matchQuery = {};
        matchQuery['pages.' + map[type] + '._id'] = id;
    Project.aggregate([
         // Match documents
        { '$match': matchQuery },

        // Unwind the pages array
        { '$unwind': '$pages' },

        // Unwind the 'texts' array
        { '$unwind': '$pages.' + [map[type]] },

        // Filter array
        { '$match': matchQuery},

        // Re-form
        { '$group': {
          '_id': '$_id',
          'data': { '$push': '$pages.' + [map[type]]}
        }}
      ],
      function(err, projects) {
        err
          ? res.json(500, {error: err.message})
          : res.json(200, {data: projects[0].data[0]});
    });
  };
};