Check whether File column contains data

{% assign track_record = entities['musdyn_track'][request.params.id] %}
{% if track_record.musdyn_audiotrack_name %}
    <script>
            webapi.safeAjax({
                type: "GET",
                url: "/_api/musdyn_tracks({{ request.params.id }})/musdyn_audiotrack",
                contentType:"application/json",
                success: function(res) {
                    console.log(res);
                    $('#main').append('<audio controls><source src="data:audio/mp3;base64,' + res.value + '" type="audio/mpeg">Your browser does not support the audio element.</audio>')
                },
                error: function(xhr, status, error){
                    var errorMessage = xhr.status + ': ' + xhr.statusText;
                    console.log(errorMessage);
                }
            });
    </script>
{% endif %}