JSON in Go
Golang Tutorials
Go: JSON
JSON (JavaScript Object Notation) is a lightweight data format that is easy for humans to read and write and easy for machines to parse and generate. Go provides built-in support for encoding and decoding JSON data using the standard library package
encoding/json.
Encode a Go data structure to JSON
To encode a Go data structure to JSON, you can use the json.Marshal() function, which takes a Go value and returns a byte slice containing its JSON representation. For example:
import (
"encoding/json"
"fmt"
)
type Person struct {
Name string
Age int
}
func main() {
person := Person{Name: "Alice", Age: 30}
jsonBytes, err := json.Marshal(person)
if err != nil {
panic(err)
}
fmt.Println(string(jsonBytes)) // Output: {"Name":"Alice","Age":30}
}
Decode a Go data structure to JSON
To decode JSON data into a Go data structure, you can use the json.Unmarshal() function, which takes a byte slice containing JSON data and a pointer to a Go value, and sets the value to the decoded data.
For example -
func main() {
jsonStr := `{"Name":"Bob","Age":25}`
var person Person
err := json.Unmarshal([]byte(jsonStr), &person)
if err != nil {
panic(err)
}
fmt.Println(person.Name, person.Age) // Output: Bob 25
}
Note that the field names in the Go struct must be exported (i.e. capitalized) in order to be encoded or decoded by the encoding/json package. You can use struct tags to specify custom field names in the JSON data.
For example -
type Person struct {
Name string `json:"name"`
Age int `json:"age"`
}
func main() {
person := Person{Name: "Charlie", Age: 20}
jsonBytes, err := json.Marshal(person)
if err != nil {
panic(err)
}
fmt.Println(string(jsonBytes)) // Output: {"name":"Charlie","age":20}
}