Json

JSON	GO
false, null, true
Objects {key1:value1, key2:value2, …}	map[string]interface{}
Arrays `[value1, value2, ...`	[]interface{}
Numbers
Strings

encoding/json

json.NewDecoder

Go does not appear to allow alternative types, and func Unmarshal(data []byte, v interface{}) error puts everything in a catchall type empty interface interface{}.

These require type assertion to make them usable.

https://www.digitalocean.com/community/tutorials/how-to-use-interfaces-in-go

https://stackoverflow.com/questions/14025833/range-over-interface-which-stores-a-slice

reflect

JSON and Go

package main

import (
  "fmt"
  "log"
  "os"
  "encoding/json"
  "reflect"
)

func main() {
  
  jsonBlob, err := os.ReadFile("/home/roblaing/webapps/hugo/content/joeblog/events.json")
  /* jsonBlob, err := os.ReadFile("array.json") */
  if err != nil {
    log.Fatal(err)
  } else {
    var jobj map[string]interface{}
    jerr := json.Unmarshal(jsonBlob, &jobj)
	if jerr != nil {
      fmt.Println("error:", jerr)
	}
    /* only works for jobj type map[string]interface{}, could be []interface{} */
    for k := range jobj {
      switch jobj[k].(type) {
        case string: 
          fmt.Printf("%v %v\n", k, jobj[k])
        case []interface{}:
          s := reflect.ValueOf(jobj[k])
          for i := 0; i < s.Len(); i++ {
            fmt.Printf("%T\n", s.Index(i).Interface())
          }
        default: 
        fmt.Printf("%v %T\n", k, jobj[k])
      }
    }
  }

}

The empty interfaceinterface{} is used to translate the {key: val, …} in the json file to a variable (keyvals above) holding a map[…].