使用Go将平面数据转换为嵌套JSON

Question

I'm trying to find an efficient way to convert flat data from a DB table into a nested JSON in Go.

This is my code to load my dataset into a slice of structs:

https://play.golang.org/p/_80nASVgds-

Which will produce the following json:

[{
    "Globe": "World",
    "Hemisphere": "Northern",
    "Country": "USA"
}, {
    "Globe": "World",
    "Hemisphere": "Southern",
    "Country": "Australia"
}, {
    "Globe": "World",
    "Hemisphere": "Southern",
    "Country": "Brazil"
}, {
    "Globe": "World",
    "Hemisphere": "Southern",
    "Country": "South Africa"
}, {
    "Globe": "World",
    "Hemisphere": "Northern",
    "Country": "Spain"
}]

I'd like to be able to be able to encode the same dataset into something like:

type Globe struct {
    Name       string
    Hemisphere []Hemisphere
}

type Hemisphere struct {
    Name    string
    Country []Country
}

type Country struct {
    Name string
}

So I could marshal Globe and get the same dataset in a nested form as such:

https://play.golang.org/p/r9OlCw_EwSA

{
    "Name": "World",
    "Hemisphere": [{
        "Name": "Northern",
        "Country": [{
            "Name": "USA"
        }, {
            "Name": "Spain"
        }]
    }, {
        "Name": "Southern",
        "Country": [{
            "Name": "Australia"
        }, {
            "Name": "South Africa"
        }, {
            "Name": "Brazil"
        }]
    }]
}

Is there any effective way of doing this other than looping through the dataset constantly and checking if a given property has already been added into the struct? My dataset is not ordered which makes it even more difficult to control the additions through loops.