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Diffstat (limited to 'src/encoding/json/example_test.go')
-rw-r--r-- | src/encoding/json/example_test.go | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/src/encoding/json/example_test.go b/src/encoding/json/example_test.go new file mode 100644 index 000000000..ca4e5ae68 --- /dev/null +++ b/src/encoding/json/example_test.go @@ -0,0 +1,161 @@ +// 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 + // = } + // =] +} |