Cannot see media field in my endpoint for my content type

[shiddu_mageppa]

it works.
I have a collection with a field named file which is of media type.

following is the code:

var mediaid = 12;

        fetch('http://localhost:1337/api/sample-medias/' + mediaid + "?populate=file")
        .then(function (response) {
            return response.json();
        }).then(function (data) {
            console.log(data);
        });