mapstructure json into a structure with nested dictionary - go

Question

I am new to golang. I have a json file with nested structures that I want to parse and populate.
I am trying to use mapstructure to try and populate. I am able to do it for simple structures. But when it comes to array for dictionaries(key:struct). The map[string]interface{} seems to fail with runtime error: index out of range.
I tried to do the following for the json example below.
type Window struct {
loc []int
wrtc string
label string
}
type View struct {
windows []Window
}
type Views struct {
views []View
}
type Desktop struct {
views []Views `mapstructure:views`
rotation_speed string `mapstructure:"rotationSpeed" json:rotationSpeed"`
}
func main() {
file, _ := ioutil.ReadFile("test.json")
data := Desktop{}
_ = json.Unmarshal([]byte(file), &data)
fmt.Println("data: ", data.views[0])
}
{
"desktop": {
"view": [{// configs for view1
"random_id1": {
"loc": [0,0,640,360],
"wrtc": "some string",
"label": "window 1"
},
"random_id213443": {
"loc": [640,360,1280,720],
"wrtc": "some string blah",
"label": "window 2"
},
// more windows with random ids....
},
{
// configs for view2...
}
],
"rotationSpeed": 30
}
Since the window id is random I am not able to define it in a struct.
I tried using mapstructure:",squash" but that seems to fail as well.
I appreciate any help with this.

Answer 1

#Burak Serdar is right
You don't need mapstructure. JSON unmarshaling can deal with this.
you code have many error, like struct, uppercase, 'views' etc..
follow is a demo:
package main
import (
"encoding/json"
"fmt"
)
var data = `
{
"desktop":{
"view":[
{
"random_id1_1":{
"loc":[
0,
0,
640,
360
],
"wrtc":"some string",
"label":"window 1"
},
"random_id1_2":{
"loc":[
640,
360,
1280,
720
],
"wrtc":"some string blah",
"label":"window 2"
}
},
{
"random_id2_1":{
"loc":[
0,
0,
640,
360
],
"wrtc":"some string",
"label":"window 1"
},
"random_id2_2":{
"loc":[
640,
360,
1280,
720
],
"wrtc":"some string blah",
"label":"window 2"
}
}
],
"rotationSpeed":30
}
}
`
type Window struct {
Loc []int
Wrtc string
Label string
}
type Desktop struct {
View []map[string]Window
Rotation_speed int `json:"rotationSpeed" mapstructure:"rotationSpeed"`
}
type Config struct {
Desktop Desktop
}
func main() {
c := Config{}
json.Unmarshal([]byte(data), &c)
fmt.Println("json.Unmarshal: ", c)
}
json.Unmarshal: {{[map[random_id1_1:{[0 0 640 360] some string window 1} random_id1_2:{[640 360 1280 720] some s
tring blah window 2}] map[random_id2_1:{[0 0 640 360] some string window 1} random_id2_2:{[640 360 1280 720] some
string blah window 2}]] 30}}
also you can use mapstructure by "remain", if you want View struct
type Window struct {
Loc []int
Wrtc string
Label string
}
type View struct {
Windows map[string]Window `mapstructure:",remain"`
}
type Desktop struct {
View []View
Rotation_speed int `json:"rotationSpeed" mapstructure:"rotationSpeed"`
}
type Config struct {
Desktop Desktop
}
func main() {
c2 := Config{}
m := map[string]interface{}{}
_ = json.Unmarshal([]byte(data), &m)
mapstructure.Decode(m, &c2)
fmt.Println("mapstructure: ", c2)
}