Merge branch 'master' of https://github.com/xujihui1985/learninggo in…

…to master

json/customize_unmarshal/main.go

@@ -0,0 +1,118 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+)
+
+// http://gregtrowbridge.com/golang-json-serialization-with-interfaces/
+type ColoredThing interface {
+	Color() string
+}
+
+type ColorfulEcosystem struct {
+	Things []ColoredThing `json:"things"`
+}
+
+func (ce *ColorfulEcosystem) UnmarshalJSON(b []byte) error {
+	var objMap map[string]*json.RawMessage
+	err := json.Unmarshal(b, &objMap)
+	if err != nil {
+		return err
+	}
+	var rawMessages []*json.RawMessage
+	err = json.Unmarshal(*objMap["things"], &rawMessages)
+	if err != nil {
+		return err
+	}
+	ce.Things = make([]ColoredThing, len(rawMessages))
+	var m map[string]string
+
+	for idx, rawMessage := range rawMessages {
+		err = json.Unmarshal(*rawMessage, &m)
+		if err != nil {
+			return err
+		}
+
+		if m["type"] == "plant" {
+			var p Plant
+			err := json.Unmarshal(*rawMessage, &p)
+			if err != nil {
+				return err
+			}
+			ce.Things[idx] = &p
+		} else if m["type"] == "animal" {
+			var a Animal
+			err := json.Unmarshal(*rawMessage, &a)
+			if err != nil {
+				return err
+			}
+			ce.Things[idx] = &a
+		} else {
+			return errors.New("unsupported type " + m["type"])
+		}
+	}
+	return nil
+}
+
+type Plant struct {
+	MyColor string `json:"color"`
+}
+
+type Animal struct {
+	MyColor string `json:"color"`
+}
+
+func (p *Plant) Color() string {
+	return p.MyColor
+}
+
+func (a *Plant) MarshalJSON() ([]byte, error) {
+	return json.Marshal(map[string]string{
+		"type":  "plant",
+		"color": a.Color(),
+	})
+}
+
+func (a *Animal) Color() string {
+	return a.MyColor
+}
+
+func (a *Animal) MarshalJSON() ([]byte, error) {
+	return json.Marshal(map[string]string{
+		"type":  "animal",
+		"color": a.Color(),
+	})
+}
+
+func main() {
+	fern := &Plant{MyColor: "green"}
+	flower := &Plant{MyColor: "purple"}
+
+	panther := &Animal{MyColor: "black"}
+	lizard := &Animal{MyColor: "green"}
+
+	// Then let's create a ColorfulEcosystem
+	colorfulEcosystem := ColorfulEcosystem{
+		Things: []ColoredThing{
+			fern,
+			flower,
+			panther,
+			lizard,
+		},
+	}
+
+	byteSlice, _ := json.Marshal(colorfulEcosystem)
+	fmt.Println(string(byteSlice))
+
+	ce := ColorfulEcosystem{}
+
+	err := json.Unmarshal(byteSlice, &ce)
+	if err != nil {
+		panic(err)
+	}
+	for _, c := range ce.Things {
+		fmt.Println(c.Color())
+	}
+}

json/marshal/main.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+type Plant struct {
+	MyColor string
+}
+
+func (p Plant) MarshalJSON() ([]byte, error) {
+	m := make(map[string]string)
+	m["type"] = "plant"
+	m["color"] = p.MyColor
+	return json.Marshal(m)
+}
+
+type Animal struct {
+	MyColor string
+}
+
+func main() {
+	p := Plant{MyColor: "green"}
+	a := Animal{MyColor: "red"}
+
+	b, _ := json.Marshal(p)
+	ba, _ := json.Marshal(a)
+
+	fmt.Println(string(b))
+	fmt.Println(string(ba))
+
+}