在Go中表示此JSON的最佳方法？

Question

I am writing an endpoint to return data for Geckoboard, it excepts a format like so:

{
  "item": [
    {
      "value": "274057"
    },
    [
      "38594",
      "39957",
      "35316",
      "35913",
      "36668",
      "45660",
      "41949"
    ]
  ]
}

"item" is an array of varying structures. How would I represent this data in Go?

Note: this is not on how I would unmarshal this, I need to generate this format.

Answer 1

This stuff is easier than you might think. It's just not that well documented for the casual reader. I would recommend ffjson over normal json tho. It's made up in such a manner that you don't need to change your syntax other than the library name.

It's easy as this:

type User struct {
    Id      int    `json:'id'`
    Name    string `json:name`
    SomeId1 int    `json:some_id_1`
    SomeId2 int    `json:some_id_2`
    SomeId3 int    `json:some_id_3`
    SomeId4 int    `json:some_id_4`
}

item := map[string]User{}
for i := 0; i < 10; i++ {
    item[strconv.itoa(i)] = User{i, "Username X", 38393, 29384, 12393, 123981}
}
buf, err := ffjson.Marshal(&item)

The downside of structs (even in ffjson still) is that reflection will always be used, which, in times that you're in need of high performance, you will waste a lot of CPU cycles. ffjson is 2-3 times faster than normal json when you keep it to maps. This way the library can compile every data-structure you marshal and re-use it instead of constantly inspecting the data-integrity/structure with reflect.