我要忽略的更新覆盖字段上的Gorm模型

Question

I'm using gorm(GoLang) with PostgreSQL. recently I've decided to use association with gorm in order to save time and for best practice...

So the issue is that I want to update a model without overwriting all his fields.

for example' I have this structs:

type Car struct {
    gorm.Model
    CarModels []CarModel `json:"car_models"`
    Foo       string     `json:"foo"`
}

type CarModel struct {
    gorm.Model
    Name  string `json:"name"`
    Bar   string `json:"-"`
    CarID uint   `json:"car_id"`
}

• The user can only see the car model name and car_id.
  1. The user changed the car model name and asked to save it.
  2. I want to save the changes to DB and Gorm db.Update()
  3. so I save the Car model (not the CarModel !!!) because they are associated

And the issue is that field Bar is empty on DB... because I didn't return it to the client...

I've tried to find an answer here and on Gorm docs and didn't find any...

Does someone have any idea how to handle this problem?