How to define a nullable relation type with hasMany

[michaelboke]

I got the following usecase:
I got books and Shelfs, Books can be assigned to Shelfs.
There is the case a book isnt assigned to a shelf and there for the shelf_id should be nil

I tried the Nullable command on a Field, but does not work.

Model("Shelf", func() {

    Field("id", gorma.Integer, func() {
        PrimaryKey()
    })

    HasMany("Books", "Book")
    )}

Model("Book", func() {

    Field("id", gorma.Integer, func() {
        PrimaryKey()
    })

    //Hack not working
    Field("shelf_id", gorma.Integer, func() {
        Nullable()
    })
})

This will generate a model like:

type Book struct {
    ID         int `gorm:"primary_key"` // primary key
    ShelfID      int // has many Book
}

type Shelf struct {
    ID         int `gorm:"primary_key"` // primary key
    Books    []Book   // has many Books
}

But what i actualy want is (note the pointer to *int)

type Book struct {
    ID         int `gorm:"primary_key"` // primary key
    ShelfID    *int // has many Book
}

How can i achieve this? or is this even possible.

[bketelsen]

My suggestion: try again after #118 lands and see if that fixes this.