Golang: Marshal and Unmarshal

As an ESL speaker, I was initially confused when I first encountered the term “marshaling”.

To marshal generally means to bring together and arrange things in an effective or organized way. For example, “She marshaled her thoughts before answering the question.” It’s also commonly used in a military context, as in “marshaling the troops,” which means positioning them in the proper order or rank ¹

In computer science, marshaling refers to the process of converting the memory representation of an object into a data format suitable for storage or transmission. ²

In other words, it’s the process of converting data structures into standardized formats (like JSON), which is often used in HTTP requests.

func Marshal(v any) ([]byte, error)

package main

import (
    "encoding/json"
    "fmt"
)

func main() {
    type Player struct {
        Name    string
        Club    string
        Number  int
    }
    player := Player{
        Name: "Kerem Akturkoglu",
        Club: "SL Benfica",
        Number: 17,
    }
    jsonData, err := json.Marshal(player)
    if err != nil {
        fmt.Println("error:", err)
        return
    }

    fmt.Println(string(jsonData))
    // output: {"Name":"Kerem Akturkoglu","Club":"SL Benfica","Number":17}
}

On the other hand, unmarshaling is the process of taking encoded data in a specific format and converting it back into a Go value.

func Unmarshal(data []byte, v interface{}) error

package main

import (
    "encoding/json"
    "fmt"
)

func main() {
    data := `{"Name":"Kerem Akturkoglu","Club":"SL Benfica","Number":17}`

    type Player struct {
        Name   string `json:"Name"`
        Club   string `json:"Club"`
        Number int    `json:"Number"`
    }

    var player Player

    err := json.Unmarshal([]byte(data), &player)
    if err != nil {
        fmt.Println("error:", err)
        return
    }

    fmt.Printf("Name: %s, Club: %s, Number: %d\n",
        player.Name, player.Club, player.Number)

    // output: Name: Kerem Akturkoglu, Club: SL Benfica, Number: 17 
}

XML examples

package main
import (
    "encoding/xml"
    "fmt"
)

func main() {
    type Player struct {
        Name    string
        Club    string
        Number  int
    }
    player := Player{
        Name: "Kerem Akturkoglu",
        Club: "SL Benfica",
        Number: 17,
    }
    xmlData, err := xml.Marshal(player)
    if err != nil {
        fmt.Println("error:", err)
        return
    }

    fmt.Println(string(xmlData))

    // output:
    // <Player><Name>Kerem Akturkoglu</Name><Club>SL Benfica</Club><Number>17</Number></Player>
}

package main

import (
    "encoding/xml"
    "fmt"
)

func main() {
    data := `<Player><Name>Kerem Akturkoglu</Name><Club>SL Benfica</Club><Number>17</Number></Player>`

    type Player struct {
        Name   string `xml:"Name"`
        Club   string `xml:"Club"`
        Number int    `xml:"Number"`
    }

    var player Player

    err := xml.Unmarshal([]byte(data), &player)
    if err != nil {
        fmt.Println("error:", err)
        return
    }

    fmt.Printf("Name: %s, Club: %s, Number: %d\n",
        player.Name, player.Club, player.Number)

    // output: Name: Kerem Akturkoglu, Club: SL Benfica, Number: 17 
}

XML examples

Further Reading