main.go

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"strings"
)

func main() {
	if err := eventReceived("x-one", []byte(`{ "name": "Dan" }`)); err != nil {
		log.Fatalf("error on event received: %v", err)
	}

	if err := eventReceived("x-two", []byte(`{ "age": 21 }`)); err != nil {
		log.Fatalf("error on event received: %v", err)
	}
}

func eventReceived(eventType string, eventJSON []byte) (err error) {
	switch strings.ToLower(eventType) {
	case "x-one":
		target := one{}
		if err = json.Unmarshal(eventJSON, &target); err != nil {
			return
		}
		processOne(target)
	case "x-two":
		target := two{}
		if err = json.Unmarshal(eventJSON, &target); err != nil {
			return
		}
		processTwo(target)
	default:
		return fmt.Errorf("%q is not a valid event type", eventType)
	}
	return
}

func processOne(o one) {
	fmt.Printf("PROCESSING: %v\n", o)
}

func processTwo(t two) {
	fmt.Printf("PROCESSING: %v\n", t)
}

type one struct {
	Name string `json:"name"`
}

type two struct {
	Age int `json:"age"`
}