test.go

package main
import (
  "encoding/json"
  "log"
)

type Usage struct {
	IP string
	Connections int
	RxBytes int64
	RxPackets int64
	TxBytes int64
	TxPackets int64
}

func (a *Usage) UnmarshalJSON(b []byte) error { 
  row := []interface{}{}
  if err := json.Unmarshal(b, &row); err != nil {
    return err
	}
  a.IP = row[0].(string)
  a.Connections = int(row[1].(float64))
  a.RxBytes = int64(row[2].(float64))
  a.RxPackets = int64(row[3].(float64))
  a.TxBytes = int64(row[4].(float64))
  a.TxPackets = int64(row[5].(float64))
  return nil
}

type AllUsage struct {
    Data []Usage `json:"data"`
    Columns []string `json:"columns"`
}

func main() {
	data := `{"columns":["ip","conns","rx_bytes","rx_pkts","tx_bytes","tx_pkts"],"data":[["192.168.1.3",49696,2628175385,2659880,55066470,1003162],["192.168.1.24",10041,463614449,498139,19305939,209256],["192.168.1.98",2546,295968431,221923,5485406,29572],["192.168.1.97",61126,235012840,250040,26214901,132459],["192.168.1.80",12492,90917682,93215,7744563,33601],["192.168.1.21",4642,21735476,59719,4862780,31633],["192.168.1.94",20164,11189262,43500,5446658,43895],["192.168.1.5",8805,9865985,17105,7242133,17953],["192.168.2.2",33454,3153765,21368,554444,8679],["192.168.1.30",1509,1214044,2059,668581,2748],["192.168.1.12",6844,735386,6594,3388692,16999],["192.168.1.177",831,582732,1247,331983,1379],["192.168.1.6",365,163282,457,58538,508],["192.168.1.8",1409,147000,1750,133076,1751],["192.168.1.174",513,70918,206,10768,87],["192.168.1.4",44,34712,75,26192,100],["192.168.1.109",68,25267,193,45116,196],["192.168.1.201",42,7516,26,9104,29],["192.168.1.202",38,7492,26,12276,29],["192.168.1.200",39,7492,26,11047,29],["192.168.1.13",140,5232,48,3048,48],["192.168.1.9",117,3040,40,3040,40],["192.168.1.247",2110,0,0,111496,724]]}`
  usage := &AllUsage{}
	json.Unmarshal([]byte(data), usage)
  log.Printf("usage %d %s", len(usage.Data), usage.Data)
  log.Printf("Columns %d %s", len(usage.Columns), usage.Columns)

}