从数据库获取到了菜单列表数据，这些菜单数据通过字段 ParentID 表示父子层级关系，现在需要将菜单列表数据转成树状的实例对象。
数据库取出的初始数据：
raw := []Menu{
{Name: "一级菜单 1", ID: 1, PID: 0},
{Name: "一级菜单 2", ID: 2, PID: 0},
{Name: "一级菜单 3", ID: 3, PID: 0},
{Name: "二级菜单 1-1", ID: 11, PID: 1},
{Name: "二级菜单 1-2", ID: 12, PID: 1},
{Name: "二级菜单 1-3", ID: 13, PID: 1},
{Name: "二级菜单 2-1", ID: 21, PID: 2},
{Name: "二级菜单 2-2", ID: 22, PID: 2},
{Name: "二级菜单 2-3", ID: 23, PID: 2},
}
需要得到的目标数据：
{
"name":"根菜单",
"id":0,
"pid":0,
"SubMenus":[
{
"name":"一级菜单 1",
"id":1,
"pid":0,
"SubMenus":[
{
"name":"二级菜单 1-1",
"id":11,
"pid":1
},
{
"name":"二级菜单 1-2",
"id":12,
"pid":1
},
{
"name":"二级菜单 1-3",
"id":13,
"pid":1
}
]
},
{
"name":"一级菜单 2",
"id":2,
"pid":0,
"SubMenus":[
{
"name":"二级菜单 2-1",
"id":21,
"pid":2
},
{
"name":"二级菜单 2-2",
"id":22,
"pid":2
},
{
"name":"二级菜单 2-3",
"id":23,
"pid":2
}
]
},
{
"name":"一级菜单 3",
"id":3,
"pid":0
}
]
}
package main
import (
"encoding/json"
"fmt"
)
func main() {
// 数据库里存储的菜单
rawMenus := []Menu{
{Name: "一级菜单 1", ID: 1, PID: 0},
{Name: "一级菜单 2", ID: 2, PID: 0},
{Name: "一级菜单 3", ID: 3, PID: 0},
{Name: "二级菜单 1-1", ID: 11, PID: 1},
{Name: "二级菜单 1-2", ID: 12, PID: 1},
{Name: "二级菜单 1-3", ID: 13, PID: 1},
{Name: "二级菜单 2-1", ID: 21, PID: 2},
{Name: "二级菜单 2-2", ID: 22, PID: 2},
{Name: "二级菜单 2-3", ID: 23, PID: 2},
}
menu := &Menu{
Name: "根菜单",
PID: 0,
}
for _, rm := range rawMenus {
menu.setSubMenus(rm)
}
// 打印结果
b, _ := json.Marshal(menu)
fmt.Println(string(b))
}
type Menu struct {
Name string `json:"name"`
ID int `json:"id"`
PID int `json:"pid"`
SubMenus []Menu `json:",omitempty"`
}
func (m *Menu) setSubMenus(menu Menu) bool {
if menu.PID == m.ID {
m.SubMenus = append(m.SubMenus, menu)
return true
}
for i := range m.SubMenus {
if m.SubMenus[i].setSubMenus(menu) {
return true
}
}
return false
}
Golang for 遍历使用 for _, item := range slice 时，item 是一份遍历元素的复制，而使用 for i := range slice 时，slice[i] 则是遍历元素本身，使用时需要注意切片扩容带来的地址变化问题。