Can't create a nested struct

Question

I have to format a json in go and I have some problems. the string literal that I have used in java is the following:

   String jsonString= "{\"stream\":\"temperatura2\",\r\n" + 
        "\"sensor\":\"ec6c613a-66b4-4584-fb37-5f7cac130f7d\",\r\n" + 
        "\"values\":[{\"time\":\"2019-03-10T11:30:00Z\",\"components\":{\"alfanum\":\"99.0\"}}]}\r\n";

So I created this struct:

type YuccaDataStream struct {
    Stream string `json:"stream"`
    Sensor string `json:"sensor"`
    Values []struct {
       Time       time.Time `json:"time"`
         Components struct {
         Alfanum string `json:"alfanum"`
      } `json:"components"`
   } `json:"values"`
}

Is that struct correct? I don't know how to create an instance of that struct and fill it with the current time.

Possible duplicate of https://stackoverflow.com/questions/26866879/initialize-nested-struct-definition-in-golang. — Charlie Tumahai, Nov 28 '19 at 20:35
I'm trying to learn go and I don't know named types, I will look. Thank you :) — gianpaolo, Nov 28 '19 at 21:04

score 1 · Answer 1 · answered Nov 28 '19 at 20:41

don't do that.

package main

import (
    "fmt"
    "time"
)

func main() {
    fmt.Println("Hello, playground")

    y := YuccaDataStream{
        Values: []struct {
            Time       time.Time
            Components struct {
                Alfanum string
            }
        }{

            //
            struct {
                Time       time.Time
                Components struct {
                    Alfanum string
                }
            }{Time: time.Now(), Components: struct{ Alphanum string }{Alphanum: "aaa"}},
            //
            struct {
                Time       time.Time
                Components struct {
                    Alfanum string
                }
            }{Time: time.Now(), Components: struct{ Alphanum string }{Alphanum: "bbb"}},
            //

        },
    }
}

type YuccaDataStream struct {
    Stream string `json:"stream"`
    Sensor string `json:"sensor"`
    Values []struct {
        Time       time.Time `json:"time"`
        Components struct {
            Alfanum string `json:"alfanum"`
        } `json:"components"`
    } `json:"values"`
}

Thank you very much. Looks very complicated. – gianpaolo Nov 28 '19 at 21:08 — gianpaolo, Nov 28 '19 at 21:08

ShayK · Answer 2 · 2019-11-28T21:19:52.607

1

How about this:

package main

import (
    "fmt"
    "time"
    "encoding/json"
)

type YuccaDataStream struct {
    Stream string `json:"stream"`
    Sensor string `json:"sensor"`
    Values []Value `json:"values"`
}

type Value struct {
    Time time.Time `json:"time"`
    Components `json:"components"`
}

type Components struct {
    Alfanum string `json:"alfanum"`
}

func main() {
    data := []byte(`{"stream": "temperatura2","sensor": "ec6c613a-66b4-4584-fb37-5f7cac130f7d","values": [{"time": "2019-03-10T11:30:00Z","components": {"alfanum": "99.0"}}]}`)

    var unmarshaled YuccaDataStream
    err := json.Unmarshal(data, &unmarshaled)
    if err != nil {
        panic(err)
    }
    fmt.Printf("%v",unmarshaled)
}

try in go playground

edited Nov 28 '19 at 21:19

answered Nov 28 '19 at 21:14

ShayK

429
3
6

Thank you. How do I use Yr syntax to insert for example the current time and then marshal? – gianpaolo Nov 28 '19 at 21:55
If you want to marshal you can create a variable of type YuccaDataStream, fill the data and in the time field use time.Now.UTC(). then you can use json.Marshal. – ShayK Nov 28 '19 at 22:10

Can't create a nested struct

2 Answers2