Golang mapping JSON into struct

Question

I have a struct as below:

type Item struct {
  ID         int16 `json:"id"`
  SubItem    *Item `json:"sub_item"`
}

And the JSON as below:

{
  "id": 100,
  "sub_item": 110
}

If I use json.Unmarshal(json, &item), the json field sub_item is the Item.ID, so cannot mapping into struct.

I want to find the SubItem by the subitem id before json unmarshal, but I don't know how to do it. Or is there any way to resolve this problem? thanks a lot.

Do you want to unmarshal object like linked-list?

mattn
– mattn

2017-06-30 09:14:14 +00:00
Commented Jun 30, 2017 at 9:14 — mattn
– mattn, Commented Jun 30, 2017 at 9:14

LucianoQ · Accepted Answer · 2017-06-30 09:58:22Z

4

*Item is a golang pointer to a struct. It cannot contain a int16 (that is a "pointer" in your json semantic).

You can handle this programmatically after Unmarshaling.

Struct must be:

type Item struct {
    ID         int16 `json:"id"`
    SubItem    *Item
    SubItemInt int16 `json:"sub_item"`
}

and then you should do something like this:

items := make(map[int16]*Item)
[...]
for k := range items {
    items[k].SubItem = items[items[k].SubItemInt]
}

edited Jun 30, 2017 at 9:58

answered Jun 30, 2017 at 9:30

LucianoQ

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