结合泛型和reflect写一个groupBy转map的工具类

// GroupByMap 切片按key(字段)分组转map
func GroupByMap[T interface{}](values []*T, key string) map[string][]*T {
   mapObj := make(map[string][]*T)
   // 先去重
   for _, groupKey := range removeRepeatedElement(values, key) {
      // 再过滤
      arr := filter(values, key, groupKey)
      mapObj[groupKey] = arr
   }
   return mapObj
}

// 过滤,将每个key对应的val放置切片
func filter[T interface{}](arr []*T, key, keyAsVal string) (newArr []*T) {
   newArr = make([]*T, 0)
   for _, item := range arr {
      itemVal := reflect.ValueOf(item).Elem().FieldByName(key).String()
      if itemVal == keyAsVal {
         newArr = append(newArr, item)
      }
   }
   return newArr
}

// 将所有的key取出来并去重
func removeRepeatedElement[T interface{}](arr []*T, key string) (newArr []string) {
   newArr = make([]string, 0)
   for i := 0; i < len(arr); i++ {
      repeat := false
      // 反射取key对应的val
      ikeyAsVal := reflect.ValueOf(arr[i]).Elem().FieldByName(key).String()
      for j := i + 1; j < len(arr); j++ {
         // 反射取key对应的val
         jkeyAsVal := reflect.ValueOf(arr[j]).Elem().FieldByName(key).String()
         if ikeyAsVal == jkeyAsVal {
            repeat = true
            break
         }
      }
      if !repeat {
         newArr = append(newArr, ikeyAsVal)
      }
   }
   return newArr
}