golang struct 轉map 及 map[string]*Struct 初始化和遍歷

package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"reflect"
	"strconv"
	"time"
)

type User struct {
	a string
	b string
}

type S struct {
	User
	Name    string
	Age     int
	Address string
}

//結構體轉map方法1
func Struct2Map(obj interface{}) map[string]interface{} {
	t := reflect.TypeOf(obj)
	v := reflect.ValueOf(obj)

	var data = make(map[string]interface{})
	//func (v Value) NumField() int,  返回v持有的結構體類型值的字段數，如果v的Kind不是Struct會panic
	for i := 0; i < t.NumField(); i++ {
		data[t.Field(i).Name] = v.Field(i).Interface()
	}
	return data
}

//結構體轉map方法2
func StructToMapViaJson(data S) map[string]interface{} {
	m := make(map[string]interface{})
	//struct 轉json
	j, _ := json.Marshal(data)
	//json 轉map
	json.Unmarshal(j, &m)
	return m
}

func FillStruct(data map[string]interface{}, obj interface{}) error {
	for k, v := range data {
		//fmt.Println("k: ", k, " v: ", v)
		err := SetField(obj, k, v)
		if err != nil {
			return err
		}
	}
	return nil
}

func SetField(obj interface{}, k string, v interface{}) error {
	//結構體屬性值
	structValue := reflect.ValueOf(obj).Elem()
	//fmt.Println("structValue: ", structValue)
	//結構體單個屬性值
	structFieldValue := structValue.FieldByName(k)
	//fmt.Println("structFieldValue: ", structFieldValue)
	if !structFieldValue.IsValid() {
		return fmt.Errorf("No such field: %s in obj", k)
	}
	if !structFieldValue.CanSet() {
		return fmt.Errorf("Cannot set %s field value", k)
	}
	//結構體屬性類型
	structFieldType := structFieldValue.Type()
	val := reflect.ValueOf(v)
	var err error
	if structFieldType != val.Type() {
		//類型轉換
		val, err = TypeConversion(fmt.Sprintf("%v", v), structFieldValue.Type().Name())
		if err != nil {
			return err
		}
	}
	structFieldValue.Set(val)
	return nil
}

func TypeConversion(value string, ntype string) (reflect.Value, error) {
	fmt.Println("call TypeConversion...")
	if ntype == "string" {
		return reflect.ValueOf(value), nil
	} else if ntype == "time.Time" {
		t, err := time.ParseInLocation("2006-01-02 15:04:05", value, time.Local)
		return reflect.ValueOf(t), err
	} else if ntype == "Time" {
		t, err := time.ParseInLocation("2006-01-02 15:04:05", value, time.Local)
		return reflect.ValueOf(t), err
	} else if ntype == "int" {
		i, err := strconv.Atoi(value)
		return reflect.ValueOf(i), err
	} else if ntype == "int8" {
		i, err := strconv.ParseInt(value, 10, 64)
		return reflect.ValueOf(int8(i)), err
	} else if ntype == "int32" {
		i, err := strconv.ParseInt(value, 10, 64)
		return reflect.ValueOf(int64(i)), err
	} else if ntype == "int64" {
		i, err := strconv.ParseInt(value, 10, 64)
		return reflect.ValueOf(i), err
	} else if ntype == "float32" {
		i, err := strconv.ParseFloat(value, 64)
		return reflect.ValueOf(float32(i)), err
	} else if ntype == "float64" {
		i, err := strconv.ParseFloat(value, 64)
		return reflect.ValueOf(i), err
	}

	//else if .......增加其他一些類型的轉換

	return reflect.ValueOf(value), errors.New("未知的類型：" + ntype)
}

func main() {

	var s S
	Types := reflect.TypeOf(s)
	//TypeData.FieldByIndex([]int{}) 返回 StructField
	//[]int{}參數: 第一個是struct類型的索引(如果索引為參數一的數據類型不是struct會報錯), 第二個是索引為參數一的結構體內屬性的索引
	//例如[]int{0,0} 會輸出[0] a string，表示索引為0的結構體User內索引為0的數據是a
	//[]int{0, 1} 會輸出[1] b string
	//[]int{1, 0}會報錯, 因為索引為1的數據是S結構體中的數據 Name string，數據類型不是struct
	res := Types.FieldByIndex([]int{0, 0})
	fmt.Println("FieldByIndex: ", res.Index, res.Name, res.Type)

	//struct to map
	info := S{Name: "xsk", Age: 22, Address: "shanghai"}
	data := Struct2Map(info)
	fmt.Println("data: ", data, "  ", "typeof(data): ", reflect.TypeOf(data))
	for k, v := range data {
		fmt.Println(k, v.(interface{}))
	}
	fmt.Println("---------")
	data1 := StructToMapViaJson(info)
	fmt.Println("data1: ", data1, "  ", "typeof(data1): ", reflect.TypeOf(data1))
	for k, v := range data1 {
		fmt.Println(k, v.(interface{}))
	}
	fmt.Println("---------")

	//map to struct
	data2 := make(map[string]interface{})
	data2["Name"] = "xsk"
	data2["Age"] = 22
	data2["Address"] = "shanghai"
	result := &S{}
	err := FillStruct(data2, result)
	fmt.Println("err: ", err, " result: ", fmt.Sprintf("%+v", *result))
	fmt.Println("---------")

	//map[string]*Struct 下面幾種初始化都行
	//第一種
	//var info1 = map[string]*S{"info": &S{Name: "mtt", Age: 23, Address: "shanghai"}}
	//第二種
	var info1 = map[string]*S{"info": &S{}, "other": &S{}}
	info1["info"].Name = "mtt"
	info1["info"].Age = 23
	info1["info"].Address = "shanghai"

	fmt.Println("info1: ", *info1["info"])
	t := reflect.TypeOf(*info1["info"])
	v := reflect.ValueOf(*info1["info"])
	for k := 0; k < t.NumField(); k++ {
		fmt.Printf("%s: %v\n", t.Field(k).Name, v.Field(k).Interface())
	}
	fmt.Println("---------")

	//第三種
	var info2 = map[string]*S{}
	info2["info"] = &S{Name: "xly", Age: 1, Address: "shanghai"}
	fmt.Println("info2: ", *info2["info"])
	ty := reflect.TypeOf(*info2["info"])
	vl := reflect.ValueOf(*info2["info"])
	for k := 0; k < ty.NumField(); k++ {
		fmt.Printf("%s: %v\n", ty.Field(k).Name, vl.Field(k).Interface())
	}

}

golang 中 map 轉 struct

package main

import (
	"fmt"
	"github.com/goinggo/mapstructure"
)

type Person struct {
    Name string
    Age int
}

func MapToStruct() {
	mapInstance := make(map[string]interface{})
	mapInstance["Name"] = "liang637210"
	mapInstance["Age"] = 28

	var person Person
	//將 map 轉換為指定的結構體
	if err := mapstructure.Decode(mapInstance, &person); err != nil {
		fmt.Println(err)
	}
	fmt.Printf("map2struct后得到的 struct 內容為:%v", person)
}

func main(){
	MapToStruct()
}