Golang : How to convert JSON string to map and slice




Couple of simple examples on how to convert JSON string to map and slice(array).

Simple and straightforward way of converting one line of JSON string.


 package main

  import (
 "encoding/json"
 "fmt"
  )

  func main() {

 jsonStr := `{"Name":"Adam","Age":36,"Job":"CEO"}`

 personMap := make(map[string]interface{})

 err := json.Unmarshal([]byte(jsonStr), &personMap)

 if err != nil {
 panic(err)
 }

 for key, value := range personMap {
 fmt.Println("index : ", key, " value : ", value)
 }

  }

Output:

index : Name value : Adam

index : Age value : 36

index : Job value : CEO

Convert multiple lines of JSON string to map and append each line into a slice(array).


 package main

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

 func main() {

 jsonStr := `[{
 "Name": "Adam",
 "Age": 36,
 "Job": "CEO"
 }, {
 "Name": "Eve",
 "Age": 34,
 "Job": "CFO"
 }, {
 "Name": "Mike",
 "Age": 38,
 "Job": "COO"
 }]`

 type Person struct {
 Name string
 Age  int
 Job  string
 }
 var people []Person

 var personMap []map[string]interface{}

 err := json.Unmarshal([]byte(jsonStr), &personMap)

 if err != nil {
 panic(err)
 }

 for _, personData := range personMap {

 // convert map to array of Person struct
 var p Person
 p.Name = fmt.Sprintf("%s", personData["Name"])
 p.Age, _ = strconv.Atoi(fmt.Sprintf("%v", personData["Age"]))
 p.Job = fmt.Sprintf("%s", personData["Job"])
 people = append(people, p)

 }
 fmt.Println(people)

 } 

Output:

[{Adam 36 CEO} {Eve 34 CFO} {Mike 38 COO}]

References:

https://www.socketloop.com/tutorials/golang-iterate-map

https://www.socketloop.com/references/golang-encoding-json-decoder-decode-function-example

https://www.socketloop.com/tutorials/golang-covert-map-slice-array-to-json-xml-format

  See also : Golang : Covert map/slice/array to JSON or XML format





By Adam Ng

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