Json unmarshal type model in golang

Question

I have a RESTful service that returns response similar to show below:

"Basket" : {
  "Count": 1,
  "Fruits": {[
    {
      "Name":"Mango", 
      "Season":"Summer"
    },
    {
      "Name":"Fig", 
      "Season":"Winter"}
  ]}
}

I am trying to create Go lang model to unmarshal the contents. Following is the code I have tried:

type Response struct {
    Count   int
    Fruits []Fruit
}

type Fruit struct {
    Name string
    Season string
}

But when I marshal the Response object in my test code I don't see similar json. (https://play.golang.org/p/EGKqfbwFvW) Marshalled data always appears as :

{
  "Count":100,
  "Fruits":[
    {"Name":"Mango","Season":"Summer"},
    {"Name":"Fig","Season":"Winter"}
  ]
}

Notice the Fruits appearing as array [] and not {[]} in original json. How can I model structs in golang for this response?

Answer 1

Your model is totally correct and valid, but the JSON object is not. "Fruits" doesn't have name if it should be key value pair or it should be wrapped in [] not {}.

JSON obj should be formatted like this:

{
  "Basket" : {
    "Count": 1,
    "Fruits": [
      {
        "Name":"Mango", 
        "Season":"Summer"
      },
      {
        "Name":"Fig", 
        "Season":"Winter"
      }
    ]
  }
}

And actually invalid json shouldn't work https://play.golang.org/p/yoW7t4NfI7

Answer 2

I would make 'Baskets' a struct within 'Response', create a 'BasketsData' struct, and give it all some labels.

type Fruit struct {
    Name   string `json:"Name"`
    Season string `json:"Season"`
}

type BasketData struct {
    Count  int     `json:"Count"`
    Fruits []Fruit `json:"Fruits"`
}

type Response struct {
    Basket BasketData `json:"Basket"`
}

This way you will get a top level JSON response when you marshall it.

fruitmania := []Fruit{{Name: "Mango", Season: "Summer"},
                       {Name: "Fig", Season: "Winter"}}
basket := Response{BasketData{Count: 100, Fruits: fruitmania}}

b, _ := json.Marshal(basket)
fmt.Println(string(b))

checkit-checkit out: https://play.golang.org/p/TuUwBLs_Ql