not seems to work fine, aggregate is for [Model instances](http://mongoosejs.com/docs/api.html#model_Model.aggregate), not Query instances:
```
$ http GET http://localhost:8080/backend-server/message?widget=5136319693c650066f000002
HTTP/1.1 500 Internal Server Error
TypeError: Object #<Query> has no method 'aggregate'
    at module.exports.app.post.MessageModel.body (/home/elishowk/code/backend-server/modules/message/route.js:35:43)
```