是否有可能使GORM用空切片而不是nil填充nil值？

I'm currently working on a project and right now I have some basic Javascript

blah.map(function(lBlah) {});

blah is generated from an ajax request to a database which returns an array of objects (or slice if you prefer)

The only problem is I get a JS error: cannot read property 'map' of null this is because if my one-to-many association has no associated values at the time, it just makes that field nil instead of an empty slice so when I json.Marshal it it sends a null value instead of an empty [] which would fix all my errors, currently having to range over each struct that is returned from the database and check for nil values then make([]blah, 0) is annoying and looks messy. Is there an easier way to accomplish this? Is it possible to set a default json:"default:[]" or something?

// ForumContainer is a table in the database
type ForumContainer struct {
    gorm.Model
    ContainerName string `sql:"not null;unique"`
    AccessLevel   int    `sql:"not null;default:0"`
    MainThreads   []ForumMainThreads
}

// ForumMainThreads is the table in the database
type ForumMainThreads struct {
    gorm.Model
    ForumContainerID int    `sql:"index"`
    ThreadName       string `sql:"not null;unique"`
    Threads          int    `sql:"not null;default:0"`
    Replies          int    `sql:"not null;default:0"`
    AccessLevel      int    `sql:"not null;default:0"`
    Posts            []ForumMainThreadsPosts
}

// ForumMainThreadsPosts is a table in the database
type ForumMainThreadsPosts struct {
    gorm.Model
    UserID             int    `sql:"index"`
    ForumMainThreadsID int    `sql:"index"`
    Title              string `sql:"not null;unique"`
    Body               string `sql:"type:text;not null"`
    Sticky             bool   `sql:"not null;default:0"`
    Views              int    `sql:"not null;default:0"`
    ReplyCount         int    `sql:"not null;default:0"`
    Replies            []ForumMainPostsReplies
}

// ForumMainPostsReplies is a table in the database
type ForumMainPostsReplies struct {
    gorm.Model
    ForumMainThreadsPostsID int `sql:"index"`
    UserID                  int `sql:"index"`
    Body                    string
}

Querying is accomplished by:

db.Preload("MainThreads").Find(&forumContainers)