Go JSON emtpy pointer expiriment

gistfile1.go

// Example Go JSON where marshalling includes the field only if a value
// has been set. To acheive this, use pointers for everything.
//
// This is important when interacting with some APIs since the zero value
// from Go may not be what we want to set. (Ex: 0 for int32)
package main

import (
	"encoding/json"
	"fmt"
)

type ModifyClusterRequest struct {
	// FileStorageDir comment...
	FileStorageDir    *string   `json:"file_storage_dir,omitempty"`
	CandidatePoolSize *int32    `json:"candidate_pool_size,omitempty"`
	BlacklistedOS     []string `json:"blacklisted_os,omitempty"`
}

func main() {
	req := ModifyClusterRequest{
		CandidatePoolSize: makeInt32(42),
	}
	body, err := json.Marshal(&req)
	if err != nil {
		fmt.Println("oh dear, an error:", err)
	} else {
		fmt.Println("To JSON:", string(body))
	}

	req2 := &ModifyClusterRequest{}
	if err = json.Unmarshal(body, req2); err != nil {
		fmt.Println("oh dear, an error:", err)
	}
	fmt.Printf("Req2: %+v\n", req2)
	fmt.Println("Req2 CandidatePoolSize:", *req2.CandidatePoolSize)
}

func makeString(s string) *string { return &s }
func makeInt32(n int32) *int32    { return &n }