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| 1 | +// Copyright 2011 The Go Authors. All rights reserved. |
| 2 | +// Use of this source code is governed by a BSD-style |
| 3 | +// license that can be found in the LICENSE file. |
| 4 | + |
| 5 | +package json_test |
| 6 | + |
| 7 | +import ( |
| 8 | + "bytes" |
| 9 | + "encoding/json" |
| 10 | + "fmt" |
| 11 | + "io" |
| 12 | + "log" |
| 13 | + "os" |
| 14 | + "strings" |
| 15 | +) |
| 16 | + |
| 17 | +func ExampleMarshal() { |
| 18 | + type ColorGroup struct { |
| 19 | + ID int |
| 20 | + Name string |
| 21 | + Colors []string |
| 22 | + } |
| 23 | + group := ColorGroup{ |
| 24 | + ID: 1, |
| 25 | + Name: "Reds", |
| 26 | + Colors: []string{"Crimson", "Red", "Ruby", "Maroon"}, |
| 27 | + } |
| 28 | + b, err := json.Marshal(group) |
| 29 | + if err != nil { |
| 30 | + fmt.Println("error:", err) |
| 31 | + } |
| 32 | + os.Stdout.Write(b) |
| 33 | + // Output: |
| 34 | + // {"ID":1,"Name":"Reds","Colors":["Crimson","Red","Ruby","Maroon"]} |
| 35 | +} |
| 36 | + |
| 37 | +func ExampleUnmarshal() { |
| 38 | + var jsonBlob = []byte(`[ |
| 39 | + {"Name": "Platypus", "Order": "Monotremata"}, |
| 40 | + {"Name": "Quoll", "Order": "Dasyuromorphia"} |
| 41 | +]`) |
| 42 | + type Animal struct { |
| 43 | + Name string |
| 44 | + Order string |
| 45 | + } |
| 46 | + var animals []Animal |
| 47 | + err := json.Unmarshal(jsonBlob, &animals) |
| 48 | + if err != nil { |
| 49 | + fmt.Println("error:", err) |
| 50 | + } |
| 51 | + fmt.Printf("%+v", animals) |
| 52 | + // Output: |
| 53 | + // [{Name:Platypus Order:Monotremata} {Name:Quoll Order:Dasyuromorphia}] |
| 54 | +} |
| 55 | + |
| 56 | +// This example uses a Decoder to decode a stream of distinct JSON values. |
| 57 | +func ExampleDecoder() { |
| 58 | + const jsonStream = ` |
| 59 | + {"Name": "Ed", "Text": "Knock knock."} |
| 60 | + {"Name": "Sam", "Text": "Who's there?"} |
| 61 | + {"Name": "Ed", "Text": "Go fmt."} |
| 62 | + {"Name": "Sam", "Text": "Go fmt who?"} |
| 63 | + {"Name": "Ed", "Text": "Go fmt yourself!"} |
| 64 | +` |
| 65 | + type Message struct { |
| 66 | + Name, Text string |
| 67 | + } |
| 68 | + dec := json.NewDecoder(strings.NewReader(jsonStream)) |
| 69 | + for { |
| 70 | + var m Message |
| 71 | + if err := dec.Decode(&m); err == io.EOF { |
| 72 | + break |
| 73 | + } else if err != nil { |
| 74 | + log.Fatal(err) |
| 75 | + } |
| 76 | + fmt.Printf("%s: %s\n", m.Name, m.Text) |
| 77 | + } |
| 78 | + // Output: |
| 79 | + // Ed: Knock knock. |
| 80 | + // Sam: Who's there? |
| 81 | + // Ed: Go fmt. |
| 82 | + // Sam: Go fmt who? |
| 83 | + // Ed: Go fmt yourself! |
| 84 | +} |
| 85 | + |
| 86 | +// This example uses a Decoder to decode a stream of distinct JSON values. |
| 87 | +func ExampleDecoder_Token() { |
| 88 | + const jsonStream = ` |
| 89 | + {"Message": "Hello", "Array": [1, 2, 3], "Null": null, "Number": 1.234} |
| 90 | +` |
| 91 | + dec := json.NewDecoder(strings.NewReader(jsonStream)) |
| 92 | + for { |
| 93 | + t, err := dec.Token() |
| 94 | + if err == io.EOF { |
| 95 | + break |
| 96 | + } |
| 97 | + if err != nil { |
| 98 | + log.Fatal(err) |
| 99 | + } |
| 100 | + fmt.Printf("%T: %v", t, t) |
| 101 | + if dec.More() { |
| 102 | + fmt.Printf(" (more)") |
| 103 | + } |
| 104 | + fmt.Printf("\n") |
| 105 | + } |
| 106 | + // Output: |
| 107 | + // json.Delim: { (more) |
| 108 | + // string: Message (more) |
| 109 | + // string: Hello (more) |
| 110 | + // string: Array (more) |
| 111 | + // json.Delim: [ (more) |
| 112 | + // float64: 1 (more) |
| 113 | + // float64: 2 (more) |
| 114 | + // float64: 3 |
| 115 | + // json.Delim: ] (more) |
| 116 | + // string: Null (more) |
| 117 | + // <nil>: <nil> (more) |
| 118 | + // string: Number (more) |
| 119 | + // float64: 1.234 |
| 120 | + // json.Delim: } |
| 121 | +} |
| 122 | + |
| 123 | +// This example uses a Decoder to decode a streaming array of JSON objects. |
| 124 | +func ExampleDecoder_Decode_stream() { |
| 125 | + const jsonStream = ` |
| 126 | + [ |
| 127 | + {"Name": "Ed", "Text": "Knock knock."}, |
| 128 | + {"Name": "Sam", "Text": "Who's there?"}, |
| 129 | + {"Name": "Ed", "Text": "Go fmt."}, |
| 130 | + {"Name": "Sam", "Text": "Go fmt who?"}, |
| 131 | + {"Name": "Ed", "Text": "Go fmt yourself!"} |
| 132 | + ] |
| 133 | +` |
| 134 | + type Message struct { |
| 135 | + Name, Text string |
| 136 | + } |
| 137 | + dec := json.NewDecoder(strings.NewReader(jsonStream)) |
| 138 | + |
| 139 | + // read open bracket |
| 140 | + t, err := dec.Token() |
| 141 | + if err != nil { |
| 142 | + log.Fatal(err) |
| 143 | + } |
| 144 | + fmt.Printf("%T: %v\n", t, t) |
| 145 | + |
| 146 | + // while the array contains values |
| 147 | + for dec.More() { |
| 148 | + var m Message |
| 149 | + // decode an array value (Message) |
| 150 | + err := dec.Decode(&m) |
| 151 | + if err != nil { |
| 152 | + log.Fatal(err) |
| 153 | + } |
| 154 | + |
| 155 | + fmt.Printf("%v: %v\n", m.Name, m.Text) |
| 156 | + } |
| 157 | + |
| 158 | + // read closing bracket |
| 159 | + t, err = dec.Token() |
| 160 | + if err != nil { |
| 161 | + log.Fatal(err) |
| 162 | + } |
| 163 | + fmt.Printf("%T: %v\n", t, t) |
| 164 | + |
| 165 | + // Output: |
| 166 | + // json.Delim: [ |
| 167 | + // Ed: Knock knock. |
| 168 | + // Sam: Who's there? |
| 169 | + // Ed: Go fmt. |
| 170 | + // Sam: Go fmt who? |
| 171 | + // Ed: Go fmt yourself! |
| 172 | + // json.Delim: ] |
| 173 | +} |
| 174 | + |
| 175 | +// This example uses RawMessage to delay parsing part of a JSON message. |
| 176 | +func ExampleRawMessage_unmarshal() { |
| 177 | + type Color struct { |
| 178 | + Space string |
| 179 | + Point json.RawMessage // delay parsing until we know the color space |
| 180 | + } |
| 181 | + type RGB struct { |
| 182 | + R uint8 |
| 183 | + G uint8 |
| 184 | + B uint8 |
| 185 | + } |
| 186 | + type YCbCr struct { |
| 187 | + Y uint8 |
| 188 | + Cb int8 |
| 189 | + Cr int8 |
| 190 | + } |
| 191 | + |
| 192 | + var j = []byte(`[ |
| 193 | + {"Space": "YCbCr", "Point": {"Y": 255, "Cb": 0, "Cr": -10}}, |
| 194 | + {"Space": "RGB", "Point": {"R": 98, "G": 218, "B": 255}} |
| 195 | +]`) |
| 196 | + var colors []Color |
| 197 | + err := json.Unmarshal(j, &colors) |
| 198 | + if err != nil { |
| 199 | + log.Fatalln("error:", err) |
| 200 | + } |
| 201 | + |
| 202 | + for _, c := range colors { |
| 203 | + var dst interface{} |
| 204 | + switch c.Space { |
| 205 | + case "RGB": |
| 206 | + dst = new(RGB) |
| 207 | + case "YCbCr": |
| 208 | + dst = new(YCbCr) |
| 209 | + } |
| 210 | + err := json.Unmarshal(c.Point, dst) |
| 211 | + if err != nil { |
| 212 | + log.Fatalln("error:", err) |
| 213 | + } |
| 214 | + fmt.Println(c.Space, dst) |
| 215 | + } |
| 216 | + // Output: |
| 217 | + // YCbCr &{255 0 -10} |
| 218 | + // RGB &{98 218 255} |
| 219 | +} |
| 220 | + |
| 221 | +// This example uses RawMessage to use a precomputed JSON during marshal. |
| 222 | +func ExampleRawMessage_marshal() { |
| 223 | + h := json.RawMessage(`{"precomputed": true}`) |
| 224 | + |
| 225 | + c := struct { |
| 226 | + Header *json.RawMessage `json:"header"` |
| 227 | + Body string `json:"body"` |
| 228 | + }{Header: &h, Body: "Hello Gophers!"} |
| 229 | + |
| 230 | + b, err := json.MarshalIndent(&c, "", "\t") |
| 231 | + if err != nil { |
| 232 | + fmt.Println("error:", err) |
| 233 | + } |
| 234 | + os.Stdout.Write(b) |
| 235 | + |
| 236 | + // Output: |
| 237 | + // { |
| 238 | + // "header": { |
| 239 | + // "precomputed": true |
| 240 | + // }, |
| 241 | + // "body": "Hello Gophers!" |
| 242 | + // } |
| 243 | +} |
| 244 | + |
| 245 | +func ExampleIndent() { |
| 246 | + type Road struct { |
| 247 | + Name string |
| 248 | + Number int |
| 249 | + } |
| 250 | + roads := []Road{ |
| 251 | + {"Diamond Fork", 29}, |
| 252 | + {"Sheep Creek", 51}, |
| 253 | + } |
| 254 | + |
| 255 | + b, err := json.Marshal(roads) |
| 256 | + if err != nil { |
| 257 | + log.Fatal(err) |
| 258 | + } |
| 259 | + |
| 260 | + var out bytes.Buffer |
| 261 | + json.Indent(&out, b, "=", "\t") |
| 262 | + out.WriteTo(os.Stdout) |
| 263 | + // Output: |
| 264 | + // [ |
| 265 | + // = { |
| 266 | + // = "Name": "Diamond Fork", |
| 267 | + // = "Number": 29 |
| 268 | + // = }, |
| 269 | + // = { |
| 270 | + // = "Name": "Sheep Creek", |
| 271 | + // = "Number": 51 |
| 272 | + // = } |
| 273 | + // =] |
| 274 | +} |
| 275 | + |
| 276 | +func ExampleMarshalIndent() { |
| 277 | + data := map[string]int{ |
| 278 | + "a": 1, |
| 279 | + "b": 2, |
| 280 | + } |
| 281 | + |
| 282 | + b, err := json.MarshalIndent(data, "<prefix>", "<indent>") |
| 283 | + if err != nil { |
| 284 | + log.Fatal(err) |
| 285 | + } |
| 286 | + |
| 287 | + fmt.Println(string(b)) |
| 288 | + // Output: |
| 289 | + // { |
| 290 | + // <prefix><indent>"a": 1, |
| 291 | + // <prefix><indent>"b": 2 |
| 292 | + // <prefix>} |
| 293 | +} |
| 294 | + |
| 295 | +func ExampleValid() { |
| 296 | + goodJSON := `{"example": 1}` |
| 297 | + badJSON := `{"example":2:]}}` |
| 298 | + |
| 299 | + fmt.Println(json.Valid([]byte(goodJSON)), json.Valid([]byte(badJSON))) |
| 300 | + // Output: |
| 301 | + // true false |
| 302 | +} |
| 303 | + |
| 304 | +func ExampleHTMLEscape() { |
| 305 | + var out bytes.Buffer |
| 306 | + json.HTMLEscape(&out, []byte(`{"Name":"<b>HTML content</b>"}`)) |
| 307 | + out.WriteTo(os.Stdout) |
| 308 | + // Output: |
| 309 | + //{"Name":"\u003cb\u003eHTML content\u003c/b\u003e"} |
| 310 | +} |
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