magiconair magiconair - 4 months ago 8
JSON Question

Converting Go struct to JSON

I am trying to convert a Go struct to JSON using the

json
package but all I get is
{}
. I am certain it is something totally obvious but I don't see it.

package main

import (
"fmt"
"encoding/json"
)

type User struct {
name string
}

func main() {
user := &User{name:"Frank"}
b, err := json.Marshal(user)
if err != nil {
fmt.Printf("Error: %s", err)
return;
}
fmt.Println(string(b))
}


Then when I try to run it I get this:

$ 6g test.go && 6l -o test test.6 && ./test
{}

Answer

You need to export the User.name field so that the json package can see it. Rename the name field to Name.

package main

import (
    "fmt"
    "encoding/json"
)

type User struct {
    Name string
}

func main() {
    user := &User{Name: "Frank"}
    b, err := json.Marshal(user)
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println(string(b))
}

Output:

{"Name":"Frank"}