Mongodb, reducing a list by control

I m building an application in which I use to manage projects. A projects looks like the following :

{
  "_id": ObjectId("..."),
  "title": "MySuperProject",
  "files": [
    {
      "title":"My skiing day !",
      "right":[{
        "role":"USER",
        "access":["read"]
      }]
    },
    {
      "title":"My little dog, so cute !",
      "right":[{
        "role":"OTHER",
        "access":["read"]
      }]
    }
  ]
}

We can see two different roles here : USER and OTHER.

When I get the above project with the USER role, I need to have the following representation, without the OTHER file :

{
  "_id": ObjectId("..."),
  "title": "MySuperProject",
  "files": [
    {
      "title":"My skiing day !",
      "right":{
        "role":"USER",
        "access":["read"]
      }
    }]
}

Does it exist a way to reduce a list inside of a document based on query or should I make it manually on the result ?

I m working on nodejs and mongoose.

Thanks for your help

EDIT : In fact the right key was an ARRAY