What's the proper way to convert a json.RawMessage to a struct?

I have this struct

type SyncInfo struct {
    Target string
}

Now I query some json data from ElasticSearch. Source is of type json.RawMessage.
All I want is to map source to my SyncInfo which I created the variable mySyncInfo for.

I even figured out how to do that...but it seems weird. I first call MarshalJSON() to get a []byte and then feed that to json.Unmarshal() which takes an []byte and a pointer to my struct.

This works fine but it feels as if I'm doing an extra hop. Am I missing something or is that the intended way to get from a json.RawMessage to a struct?

var mySyncInfo SyncInfo

jsonStr, _ := out.Hits.Hits[0].Source.MarshalJSON()
json.Unmarshal(jsonStr, &mySyncInfo)

fmt.Print(mySyncInfo.Target)

As said, the underlying type of json.RawMessage is []byte, so you can use a json.RawMessage as the data parameter to json.Unmarshal.

However, your problem is that you have a pointer (*json.RawMessage) and not a value. All you have to do is to dereference it:

err := json.Unmarshal(*out.Hits.Hits[0].Source, &mySyncInfo)

Working example:

package main

import (
	"encoding/json"
	"fmt"
)

type SyncInfo struct {
	Target string
}

func main() {
	data := []byte(`{"target": "localhost"}`)
	Source := (*json.RawMessage)(&data)

	var mySyncInfo SyncInfo
	// Notice the dereferencing asterisk *
	err := json.Unmarshal(*Source, &mySyncInfo)
	if err != nil {
		panic(err)
	}

	fmt.Printf("%+v\n", mySyncInfo)
}

Output:

{Target:localhost}

Playground: http://play.golang.org/p/J8R3Qrjrzx

json.RawMessage is really just a slice of bytes. You should be able to feed it directly into json.Unmarshal directly, like so:

json.Unmarshal(out.Hits.Hits[0].Source, &mySyncInfo)

Also, somewhat unrelated, but json.Unmarshal can return an error and you want to handle that.

err := json.Unmarshal(*out.Hits.Hits[0].Source, &mySyncInfo)
if err != nil {
    // Handle
}