How to get JSON response body from http.Get - go

Question

I'm trying get body from response which is json and print this json or be able to put him to array. I find this post on stack: How to get JSON response from http.Get .
There is code:
var myClient = &http.Client{Timeout: 10 * time.Second}
func getJson(url string, target interface{}) error {
r, err := myClient.Get(url)
if err != nil {
return err
}
defer r.Body.Close()
return json.NewDecoder(r.Body).Decode(target)
}
but I don't undestand why there is "Decode(target)" and "target interface{}". What does it do? Why when I try just print json.NewDecoder(r.Body) there is nothing meaningful.

Answer 1

The function getJson in the question decodes the JSON response body for the specified URL to the value pointed to by target. The expression json.NewDecoder(r.Body).Decode(target) does the following:
create a decoder that reads from the response body
use the decoder to unmarshal the JSON to the value pointed to by target.
returns error or nil.
Here's an example use of the function. The program fetches and prints information about this answer.
func main() {
url := "https://api.stackexchange.com/2.2/answers/67655454?site=stackoverflow"
// Answers is a type the represents the JSON for a SO answer.
var response Answers
// Pass the address of the response to getJson. The getJson passes
// that address on to the JSON decoder.
err := getJson(url, &response)
// Check for errors. Adjust error handling to match the needs of your
// application.
if err != nil {
log.Fatal(err)
}
// Print the answer.
for _, item := range response.Items {
fmt.Printf("%#v", item)
}
}
type Owner struct {
Reputation int `json:"reputation"`
UserID int `json:"user_id"`
UserType string `json:"user_type"`
AcceptRate int `json:"accept_rate"`
ProfileImage string `json:"profile_image"`
DisplayName string `json:"display_name"`
Link string `json:"link"`
}
type Item struct {
Owner *Owner `json:"owner"`
IsAccepted bool `json:"is_accepted"`
Score int `json:"score"`
LastActivityDate int `json:"last_activity_date"`
LastEditDate int `json:"last_edit_date"`
CreationDate int `json:"creation_date"`
AnswerID int `json:"answer_id"`
QuestionID int `json:"question_id"`
ContentLicense string `json:"content_license"`
}
type Answers struct {
Items []*Item `json:"items"`
HasMore bool `json:"has_more"`
QuotaMax int `json:"quota_max"`
QuotaRemaining int `json:"quota_remaining"`
}
Link to complete code including code from question.

Answer 2

Here is an example:
package main
import (
"encoding/json"
"net/http"
)
func main() {
r, e := http.Get("https://github.com/manifest.json")
if e != nil {
panic(e)
}
defer r.Body.Close()
var s struct { Name string }
json.NewDecoder(r.Body).Decode(&s)
println(s.Name == "GitHub")
}
https://golang.org/pkg/encoding/json#Decoder.Decode