In Go (Golang), marshal and unmarshal refer to the process of converting data between Go data structures and a byte stream, typically in a format like JSON, XML, or other serialized formats. These processes are commonly used for encoding and decoding data when working with external systems, such as APIs or file storage.
Marshal: The marshal process involves converting a Go data structure (like a struct, map, or slice) into a byte stream. This byte stream is usually in a format that can be easily transmitted or stored, such as JSON or XML. The encoding/json package in the standard library provides a Marshal function for encoding Go values as JSON.
package main
import (
"encoding/json"
"fmt"
)
type Person struct {
Name string
Age int
}
func main() {
person := Person{"John Doe", 30}
jsonData, err := json.Marshal(person)
if err != nil {
fmt.Println("Error marshalling JSON:", err)
return
}
fmt.Println(string(jsonData))
}
Unmarshal: The unmarshal process is the reverse: it involves converting a byte stream (in a serialized format like JSON) back into a Go data structure. The encoding/json package provides the Unmarshal function for this purpose.
package main
import (
"encoding/json"
"fmt"
)
type Person struct {
Name string
Age int
}
func main() {
jsonStr := `{"Name":"John Doe","Age":30}`
var person Person
err := json.Unmarshal([]byte(jsonStr), &person)
if err != nil {
fmt.Println("Error unmarshalling JSON:", err)
return
}
fmt.Println(person)
}
In the Unmarshal function, the first argument is the byte slice containing the serialized data, and the second argument is a pointer to the variable where the unmarshaled data should be stored.