Set array element of a JSON using go-simplejson

main.go

package main

import (
	"fmt"
	"github.com/bitly/go-simplejson"
)

func testJsonArray1(pgStatsJson []*simplejson.Json) {
	fmt.Println("testJsonArray1")
	j := simplejson.New()
	pgStats := make([]interface{}, 0, 10)
	if pgStatsJson != nil {
		for _, pgStat := range pgStatsJson {
			pgStats = append(pgStats, pgStat.MustMap())
		}
	}
	j.Set("pg_stats", pgStats)
	if _, err := j.GetPath("pg_stats").Array(); err != nil {
		fmt.Println(err)
	}
	fmt.Println(j)
}

func testJsonArray2(pgStatsJson []*simplejson.Json) {
	fmt.Println("testJsonArray2")
	j := simplejson.New()
	pgStats := make([]map[string]interface{}, 0, 10) // different type
	if pgStatsJson != nil {
		for _, pgStat := range pgStatsJson {
			pgStats = append(pgStats, pgStat.MustMap())
		}
	}
	j.Set("pg_stats", pgStats)
	if _, err := j.GetPath("pg_stats").Array(); err != nil {
		fmt.Println(err)
	}
	fmt.Println(j)
}

func main() {
	pgStat1, _ := simplejson.NewJson([]byte(`{"num_bytes": 1111}`))
	pgStat2, _ := simplejson.NewJson([]byte(`{"num_bytes": 2222}`))
	testJsonArray1([]*simplejson.Json{pgStat1, pgStat2})
	testJsonArray1(nil)
	fmt.Println()
	testJsonArray2([]*simplejson.Json{pgStat1, pgStat2})
	testJsonArray2(nil)
}

running result:

testJsonArray1
&{map[pg_stats:[map[num_bytes:1111] map[num_bytes:2222]]]}
testJsonArray1
&{map[pg_stats:[]]}

testJsonArray2
type assertion to []interface{} failed
&{map[pg_stats:[map[num_bytes:1111] map[num_bytes:2222]]]}
testJsonArray2
type assertion to []interface{} failed
&{map[pg_stats:[]]}