Test the JSON decoder in go's stdlib by parsing package.json of a nodejs project.

test_json_decoder.go

package main

import (
    "os"
    "fmt"
    "encoding/json"
)

type PackageInfo struct {
    Name        string
    Main        string
    Version     string
    License     string
    Description string
}

func (info PackageInfo) String() (str string) {
    str += "<PackageInfo "
    str += "Name: " + info.Name
    str += ", Main: " + info.Main
    str += ", Version: " + info.Version
    str += ", License: " + info.License
    str += ", Description: " + info.Description
    str += ">"
    return
}

func main() {
    file, err := os.Open("package.json")
    if err != nil {
        panic(err)
    }
    defer file.Close()

    dec := json.NewDecoder(file)

    var res map[string]interface{}
    if err := dec.Decode(&res); err != nil {
        panic(err)
    }

    var info PackageInfo
    for k, v := range res {
        switch v.(type) {
        case int:
            fmt.Printf("%s : int => %s\n\n", k, v)
        case string:
            fmt.Printf("%s : string => %s\n\n", k, v)
            vs := v.(string)
            switch k {
            case "name":
                info.Name = vs
            case "main":
                info.Main = vs
            case "version":
                info.Version = vs
            case "license":
                info.License = vs
            case "description":
                info.Description = vs
            }
        case []interface{}:
            fmt.Printf("%s : array => %s\n\n", k, v)
        case map[string]interface{}:
            fmt.Printf("%s : map\n", k)
            if x, ok := v.(map[string]interface{}); ok {
                for kk, vv := range x {
                    fmt.Printf("  %s => %s\n", kk, vv)
                }
                fmt.Println()
            }
        default:
            fmt.Println(k, ": unknown type")
        }
    }

    fmt.Println(info)
}

// Refer to: http://golang.org/doc/articles/json_and_go.html