How to remove fields from json in go?

I've this struct in my code.

type AppVersion struct {
	Id            int64     `json:"id"`
	App           App       `json:"app,omitempty" out:"false"`
	AppId         int64     `sql:"not null" json:"app_id"`
	Version       string    `sql:"not null" json:"version"`
	Sessions      []Session `json:"-"`
	SessionsCount int       `sql:"-"`
	CreatedAt     time.Time `json:"created_at"`
	UpdatedAt     time.Time `json:"updated_at"`
	DeletedAt     time.Time `json:"deleted_at"`
}

I'm building a webservice and I don't need to send the App field in the JSON.
I've tried a few things to remove the field from the JSON but I haven't been able to do it.

How can I achieve this?
Is there any way to set struct as empty?

I'm using GORM as database access layer, so I'm not sure if I can do App *App, do you know if it will work?

type AppVersion struct {
    Id            int64     `json:"id"`
    App           App       `json:"-"`
    AppId         int64     `sql:"not null" json:"app_id"`
    Version       string    `sql:"not null" json:"version"`
    Sessions      []Session `json:"-"`
    SessionsCount int       `sql:"-"`
    CreatedAt     time.Time `json:"created_at"`
    UpdatedAt     time.Time `json:"updated_at"`
    DeletedAt     time.Time `json:"deleted_at"`
}

More info - json-go

You should be able to wrap your data structure into a custom type which hides the app field:

type ExportAppVersion struct {
   AppVersion
   App `json:"-"`
}

This should hide the App field from being exposed.