Marshaling and Unmarshaling in Go

Tutorial for marshaling and unmarshaling in Go, focusing on both JSON and XML data formats.

Marshaling and Unmarshaling in Go

Marshaling is the process of converting a Go object into a data format such as JSON or XML. Unmarshaling is the reverse process, converting data from formats like JSON or XML back into a Go object.

1. JSON Marshaling and Unmarshaling

Import the necessary package

import (
    "encoding/json"
    "fmt"
)

Define a Go struct

type Person struct {
    Name   string `json:"name"`
    Age    int    `json:"age"`
    Email  string `json:"email"`
}

Marshaling a Go struct to JSON

func main() {
    person := Person{
        Name:  "John Doe",
        Age:   30,
        Email: "[email protected]",
    }

    jsonData, err := json.Marshal(person)
    if err != nil {
        fmt.Println(err)
        return
    }

    fmt.Println(string(jsonData))
}

Unmarshaling JSON to a Go struct

func main() {
    jsonString := `{"name":"Jane Doe","age":25,"email":"[email protected]"}`

    var person Person
    err := json.Unmarshal([]byte(jsonString), &person)
    if err != nil {
        fmt.Println(err)
        return
    }

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

2. XML Marshaling and Unmarshaling

Import the necessary package

import (
    "encoding/xml"
    "fmt"
)

Define a Go struct

type Person struct {
    Name   string `xml:"name"`
    Age    int    `xml:"age"`
    Email  string `xml:"email"`
}

Marshaling a Go struct to XML

func main() {
    person := Person{
        Name:  "John Doe",
        Age:   30,
        Email: "[email protected]",
    }

    xmlData, err := xml.Marshal(person)
    if err != nil {
        fmt.Println(err)
        return
    }

    fmt.Println(string(xmlData))
}

Unmarshaling XML to a Go struct

func main() {
    xmlString := `<Person><name>Jane Doe</name><age>25</age><email>[email protected]</email></Person>`

    var person Person
    err := xml.Unmarshal([]byte(xmlString), &person)
    if err != nil {
        fmt.Println(err)
        return
    }

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

Handling Nested Structures

If your JSON or XML data contains nested objects, you need to define nested structs in Go.

JSON Example with Nested Structs

type Address struct {
    Street string `json:"street"`
    City   string `json:"city"`
}

type Person struct {
    Name    string  `json:"name"`
    Age     int     `json:"age"`
    Email   string  `json:"email"`
    Address Address `json:"address"`
}

func main() {
    jsonString := `{"name":"Jane Doe","age":25,"email":"[email protected]","address":{"street":"123 Main St","city":"Somewhere"}}`

    var person Person
    err := json.Unmarshal([]byte(jsonString), &person)
    if err != nil {
        fmt.Println(err)
        return
    }

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

XML Example with Nested Structs

type Address struct {
    Street string `xml:"street"`
    City   string `xml:"city"`
}

type Person struct {
    Name    string  `xml:"name"`
    Age     int     `xml:"age"`
    Email   string  `xml:"email"`
    Address Address `xml:"address"`
}

func main() {
    xmlString := `<Person><name>Jane Doe</name><age>25</age><email>[email protected]</email><address><street>123 Main St</street><city>Somewhere</city></address></Person>`

    var person Person
    err := xml.Unmarshal([]byte(xmlString), &person)
    if err != nil {
        fmt.Println(err)
        return
    }

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