How to convert JSON blob into an array of instances

json_to_instances.go

package main

import (
        "encoding/json"
        "fmt"
)

type Person struct {
        Name string
        Age int
}

var b = []byte(`{"Persons":[                                                                       
                   {"Name": "John", "Age" : 35 },                                                  
                   {"Name": "Jane", "Age" : 23 },                                                  
                   {"Name": "Mary", "Age" : 12 },                                                  
                   {"Name": "Shane", "Age": 35 },                                                  
                   {"Name": "Phil", "Age" : 87 }                                                   
               ]}`)

func main() {
        var f interface{}
        err := json.Unmarshal(b, &f)
        if err != nil {
                panic("OMG!")
        }
        
        m := f.(map[string]interface{})
        
        for k, v := range m {
                switch val := v.(type) {
                case string:
                        fmt.Println(k, "is string", val)
                case float64:
                        fmt.Println(k, "is float64", val)
                case []interface{}:
                        fmt.Println(k, "is an array:")
                        for index, value := range val {
                                fmt.Println(index, value)
                        }
                        default:
                        fmt.Println(k, "is of unknown type")
                }
        }
        
        n := m["Persons"].([]interface{})
        persons := make([]*Person, len(n))
        
        for i := range n {
                name := n[i].(map[string]interface{})["Name"].(string)
                age := n[i].(map[string]interface{})["Age"].(float64)
                persons[i] = &Person{name, int(age)}
                fmt.Println(name, int(age))
        }
}