How to get JSON response from http.Get

I’m trying read JSON data from web, but that code returns empty result. I’m not sure what I’m doing wrong here.

package main

import "os"
import "fmt"
import "net/http"
import "io/ioutil"
import "encoding/json"

type Tracks struct {
    Toptracks []Toptracks_info

type Toptracks_info struct {
    Track []Track_info
    Attr  []Attr_info

type Track_info struct {
    Name       string
    Duration   string
    Listeners  string
    Mbid       string
    Url        string
    Streamable []Streamable_info
    Artist     []Artist_info
    Attr       []Track_attr_info

type Attr_info struct {
    Country    string
    Page       string
    PerPage    string
    TotalPages string
    Total      string

type Streamable_info struct {
    Text      string
    Fulltrack string

type Artist_info struct {
    Name string
    Mbid string
    Url  string

type Track_attr_info struct {
    Rank string

func get_content() {
    // json data
    url := ""

    res, err := http.Get(url)

    if err != nil {

    body, err := ioutil.ReadAll(res.Body)

    if err != nil {

    var data Tracks
    json.Unmarshal(body, &data)
    fmt.Printf("Results: %v\n", data)

func main() {