Golang : How to unmarshal JSON inner/nested value and assign to specific struct?



Tags : golang inner-JSON unmarshal struct

Another tutorial to be recorded here after helping a newbie to Golang. His problem was how to deal with JSON data that have inner block. Such as :

 family := `{
 "name": "BiBi",
 "parents": {
 "mother": "MaMa",
 "father": "PaPa"
 }
 }`

and how to unmarshal the JSON inner/nested value of parents and assign the data to specific structure?

To deal with JSON inner block, the solution is stiil to unmarshal the JSON data with the standard way of un-marshaling JSON data and access the inner/nested values of parents by doing additional mapping to the MyMother and MyFather structs. See code example below.

 package main

 import (
  "encoding/json"
  "fmt"
 )

 type MyMother struct {
  Name string
  Mother string
 }

 type MyFather struct {
  Name string
  Father string
 }

 type Family struct {
  Name string
  Parents struct {
 Mother string
 Father string
  }
 }

 var jsonData = `{
 "name": "BiBi",
 "parents": {
 "mother": "MaMa",
 "father": "PaPa"
 }
 }`

 func main() {

  jsonFamily := &Family{}

  err := json.Unmarshal([]byte(jsonData), jsonFamily)

  if err != nil {
 fmt.Println(err)
  }

  // assign to MyMother
  mama := &MyMother{Name: jsonFamily.Name, Mother: jsonFamily.Parents.Mother}
  fmt.Println(mama.Name + " 's mother is " + mama.Mother)

  // assign to MyFather
  papa := &MyFather{Name: jsonFamily.Name, Father: jsonFamily.Parents.Father}
  fmt.Println(papa.Name + " 's father is " + papa.Father)
 }

Output :

BiBi 's mother is MaMa

BiBi 's father is PaPa

Hope that this tutorial can be useful to you.

  See also : Golang : How to create new XML file ?



Tags : golang inner-JSON unmarshal struct

By Adam Ng

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