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-rw-r--r--src/encoding/json/example_test.go161
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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 (
+ "bytes"
+ "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}
+}
+
+func ExampleIndent() {
+ type Road struct {
+ Name string
+ Number int
+ }
+ roads := []Road{
+ {"Diamond Fork", 29},
+ {"Sheep Creek", 51},
+ }
+
+ b, err := json.Marshal(roads)
+ if err != nil {
+ log.Fatal(err)
+ }
+
+ var out bytes.Buffer
+ json.Indent(&out, b, "=", "\t")
+ out.WriteTo(os.Stdout)
+ // Output:
+ // [
+ // = {
+ // = "Name": "Diamond Fork",
+ // = "Number": 29
+ // = },
+ // = {
+ // = "Name": "Sheep Creek",
+ // = "Number": 51
+ // = }
+ // =]
+}