Golang对象切片按照属性分类成Map

在Golang开发中，我们有时候需要实现像Java里面的stram -> group 类似的功能。则可以用如下实例完成。

package main

import (
"fmt"
"reflect"
)

type Student struct {
	Name string `json:"name"`
	Age  uint   `json:"age"`
}

type Teacher struct {
	Name string `json:"name"`
	Gender  uint   `json:"gender"`
}

func main() {
	var people []interface{}

	// 切片添加Student元素
	stu1 := Student{
		Name: "Ame",
		Age:  30,
	}
	stu2 := Student{
		Name: "Maybe",
		Age:  20,
	}
	stu3 := Student{
		Name: "Yus",
		Age:  30,
	}
	stu4 := Student{
		Name: "Yus",
		Age:  20,
	}
	people = append(people, stu1,stu2,stu3,stu4,)

/*	tech := Teacher{
		Name: "Rotk",
		Gender:  0,
	}
	people = append(people, tech)

	tech2 := Teacher{
		Name: "Rotk",
		Gender:  1000,
	}
	people = append(people, tech2)*/


	resMap := StructSliceToMap(people,"Age")
	for item := range resMap {
		fmt.Println("key of",item ," value is",resMap[item])
	}
}



// Struct Slice To Map : struct切片转为map切片
func StructSliceToMap(source interface{},filedName string) map[interface{}][]interface{}{
	filedIndex := 0
	v := reflect.ValueOf(source) // 判断，interface转为[]interface{}
	if v.Kind() != reflect.Slice {
		panic("ERROR: Unknown type, slice expected.")
	}
	l := v.Len()
	retList := make([]interface{}, l)
	for i := 0; i < l; i++ {
		retList[i] = v.Index(i).Interface()
	}
	if len(retList) > 0 {
		firstObj := retList[0]
		objT := reflect.TypeOf(firstObj)
		for i := 0; i < objT.NumField(); i++ {
			if objT.Field(i).Name == filedName {
				filedIndex = i
			}
		}
	}

	resMap := make(map[interface{}][]interface{})
	for _, elem := range retList {
		key := reflect.ValueOf(elem).Field(filedIndex).Interface()
		value :=  make([]interface{}, 0)
		resMap[key] = value
	}

	for _, elem := range retList {
		key := reflect.ValueOf(elem).Field(filedIndex).Interface()
		resMap[key] = append(resMap[key], elem)
	}
	return resMap
}