How can I filter populated values in sails.js?

I have model User. To simplify my issue it has not attributes (except id that is produced by sails engine):

module.exports = {

}

I have also model UserPost:

module.exports = {
    attributes: {
        user: {
            required: true,
            model: 'user'
        }
    }
}

I want to find posts of user with id equal to 42. I have that records in database, both user with id 42, and its posts.

This doesn't work:

UserPost.find().populate('user', {
    id: 42
}).exec(function(err, posts) {
    res.json(posts);
});

How can I do that?