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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package json_test
import (
"encoding/json"
"fmt"
"io"
"log"
"os"
"strings"
)
func ExampleMarshal() {
type ColorGroup struct {
ID int
Name string
Colors []string
}
group := ColorGroup{
ID: 1,
Name: "Reds",
Colors: []string{"Crimson", "Red", "Ruby", "Maroon"},
}
b, err := json.Marshal(group)
if err != nil {
fmt.Println("error:", err)
}
os.Stdout.Write(b)
// Output:
// {"ID":1,"Name":"Reds","Colors":["Crimson","Red","Ruby","Maroon"]}
}
func ExampleUnmarshal() {
var jsonBlob = []byte(`[
{"Name": "Platypus", "Order": "Monotremata"},
{"Name": "Quoll", "Order": "Dasyuromorphia"}
]`)
type Animal struct {
Name string
Order string
}
var animals []Animal
err := json.Unmarshal(jsonBlob, &animals)
if err != nil {
fmt.Println("error:", err)
}
fmt.Printf("%+v", animals)
// Output:
// [{Name:Platypus Order:Monotremata} {Name:Quoll Order:Dasyuromorphia}]
}
// This example uses a Decoder to decode a stream of distinct JSON values.
func ExampleDecoder() {
const jsonStream = `
{"Name": "Ed", "Text": "Knock knock."}
{"Name": "Sam", "Text": "Who's there?"}
{"Name": "Ed", "Text": "Go fmt."}
{"Name": "Sam", "Text": "Go fmt who?"}
{"Name": "Ed", "Text": "Go fmt yourself!"}
`
type Message struct {
Name, Text string
}
dec := json.NewDecoder(strings.NewReader(jsonStream))
for {
var m Message
if err := dec.Decode(&m); err == io.EOF {
break
} else if err != nil {
log.Fatal(err)
}
fmt.Printf("%s: %s\n", m.Name, m.Text)
}
// Output:
// Ed: Knock knock.
// Sam: Who's there?
// Ed: Go fmt.
// Sam: Go fmt who?
// Ed: Go fmt yourself!
}
// This example uses RawMessage to delay parsing part of a JSON message.
func ExampleRawMessage() {
type Color struct {
Space string
Point json.RawMessage // delay parsing until we know the color space
}
type RGB struct {
R uint8
G uint8
B uint8
}
type YCbCr struct {
Y uint8
Cb int8
Cr int8
}
var j = []byte(`[
{"Space": "YCbCr", "Point": {"Y": 255, "Cb": 0, "Cr": -10}},
{"Space": "RGB", "Point": {"R": 98, "G": 218, "B": 255}}
]`)
var colors []Color
err := json.Unmarshal(j, &colors)
if err != nil {
log.Fatalln("error:", err)
}
for _, c := range colors {
var dst interface{}
switch c.Space {
case "RGB":
dst = new(RGB)
case "YCbCr":
dst = new(YCbCr)
}
err := json.Unmarshal(c.Point, dst)
if err != nil {
log.Fatalln("error:", err)
}
fmt.Println(c.Space, dst)
}
// Output:
// YCbCr &{255 0 -10}
// RGB &{98 218 255}
}
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