Getting Service Struct by a JSON field

serviceInterface.go

// Demo link https://play.golang.org/p/J-n45Ddk_Mf
package main


import (
	"encoding/json"
	"fmt"
)

type ServiceTypeHelper struct {
	ServiceType string
}

// The interface will have all the methods we need to inherit
type ServiceInterface interface {
	Save()
}


// This function can be generated from different entities https://blog.golang.org/generate
func getServiceByType(serviceType string) ServiceInterface {

	switch serviceType {
	case "ServiceA":
		var sa ServiceA
		return &sa
	case "ServiceB":
		var sb ServiceB
		return &sb
	}
	return nil
}

type ServiceA struct {}

func (A *ServiceA) Save(){
	fmt.Println("Saving Service A")
}


type ServiceB struct {}

func (B *ServiceB)  Save(){

	fmt.Println("Saving Service B")
}

func GetService(payload string) (ServiceInterface, error) {
	
	var rh ServiceTypeHelper

	json.Unmarshal([]byte(payload), &rh)

	parsedStruct := getServiceByType(rh.ServiceType)

	err := json.Unmarshal([]byte(payload), &parsedStruct)

	if err != nil {
		fmt.Println(err)

	}

	return parsedStruct, nil
}




var sample1 = `{
   "serviceType":"ServiceA"
}`

var sample2 = `{
   "serviceType":"ServiceB"
}`


func main() {
	
	r, _ := GetService(sample1)
	
	r.Save()
	
	r, _ = GetService(sample2)
	
	r.Save()
	
}