Golang Gorm retrive one to many relation with limit - go

Question

Hello I have Room and Messages tables where where room has many messages. I want to get user rooms with limit 20 rooms and each room has only 20 messages only.
type Room struct {
gorm.Model
ID uint `json:"id" gorm:"primary_key"`
Hash string `json:"hash" binding:"required" gorm:"not null:true"`
Users []User `json:"users" gorm:"many2many:room_users"`
Messages []Message `json:"messages"`
Blocked bool `json:"blocked" gorm:"default:false"`
BlockerId uint `json:"blocker_id" gorm:"nullable:true"`
CreatedAt time.Time `json:"created_at"`
UpdatedAt time.Time `json:"updated_at"`
RoomBotData shared.RoomBotData `json:"bot_data"`
RoomBotDataID uint `json:"room_bot_data_id"`
}
type Message struct {
ID uint `json:"id" gorm:"primary_key"`
Text string `json:"text" binding:"required" gorm:"not null:true"`
UserID uint `json:"user_id" gorm:"not null:true"`
RoomID uint `json:"room_id" gorm:"not null:true"`
IsRead bool `json:"is_read" binding:"required" gorm:"default:false"`
Type string `json:"type" gorm:"default:text"`
CreatedAt time.Time `json:"created_at"`
}
I have tried preload function and set limit to 20 for message
db.Preload("Messages", func(db *gorm.DB) *gorm.DB {
return db.Limit(20)
}).Find(&rooms)
but this only get 20 messages in total for all rooms.
I also tried to get 20 messages for each room
err = db.DB.Model(&Room{}).
Order("updated_at DESC").
Limit(20).
Preload(RoomSchema.Users).
Where("id in ?", roomIds).
Find(&rooms).Error
roomMessagesChannel := make(chan map[int][]Message)
for i, room := range rooms {
go r.getRoomMessages(roomMessagesChannel, room.ID, i)
}
for i := 0; i < len(rooms); i++ {
messagesMap := <-roomMessagesChannel
firstItemOfMap := reflect.ValueOf(messagesMap).MapKeys()[0].Int()
rooms[int(firstItemOfMap)].Messages = messagesMap[int(firstItemOfMap)]
}
close(roomMessagesChannel)
I used channels to speed up the process but it cause memory leak and consume a lot of memory. I want to do that in a better way