GO parse nested json array

Question

{
    "meta": {
       "type": "RESPONSE",
       "application": "",
       "data0": {
         some data
       },
      "lv1": [
      {
        "status": "SUCCESS",
        "response-type": "JSON",
        "message": {},
        "response": {
        "more_data": "TRUE",
        "no_result": "5",
        "current_page": "1",
        "data": [[
         "1",
         "2", 
         "3"]]
        }
      }
     ]
   }
}

type response struct {
    META struct {
        LV []struct {
            RESPONSE struct {
                Data []struct {
                    array []struct {
                        val []string
                    }
                } `json:"data"`
            } `json:"response"`
        } `json:"lv1"`
    } `json:"meta"`

}

How can I get the values in the following?

"data": [[
         "1",
         "2", 
         "3"]]

I've tried both interface and struct. Using interface results in [1 2 3] of interface type and I'm not sure how I can get the values. When using struct, I ran into problem when trying to map an array of array with error message:

"cannot unmarshal array into Go struct field .data of type struct { vals []string }"

The JSON you posted is invalid somewhere...

RayfenWindspear
– RayfenWindspear

2017-09-08 20:44:07 +00:00
Commented Sep 8, 2017 at 20:44 — RayfenWindspear
– RayfenWindspear, Commented Sep 8, 2017 at 20:44

Adrian · Accepted Answer · 2017-09-08 20:44:25Z

15

It's an array of arrays of strings, not an array of structs containing arrays of structs containing strings, so you want something more like:

type response struct {
    Meta struct {
        Lv []struct {
            Response struct {
                Data [][]string `json:"data"`
            } `json:"response"`
        } `json:"lv1"`
    } `json:"meta"`
}

(I also changed the all-caps field names to match expected Go code style.)

For what it's worth, there is a handy JSON-to-Go tool here which gave me this for your input, after deleting the some data bit (which made the JSON invalid):

type AutoGenerated struct {
    Meta struct {
        Type        string `json:"type"`
        Application string `json:"application"`
        Data0       struct {
        } `json:"data0"`
        Lv1 []struct {
            Status       string `json:"status"`
            ResponseType string `json:"response-type"`
            Message      struct {
            } `json:"message"`
            Response struct {
                MoreData    string     `json:"more_data"`
                NoResult    string     `json:"no_result"`
                CurrentPage string     `json:"current_page"`
                Data        [][]string `json:"data"`
            } `json:"response"`
        } `json:"lv1"`
    } `json:"meta"`
}

answered Sep 8, 2017 at 20:44

Adrian

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2 Comments

Christian Gossain Over a year ago

The tool you linked to is incredible, thanks for sharing. I just had to delete some duplicate definitions but otherwise it generated a perfect struct. Thanks again!

Moo Master Over a year ago

Agreed! This is actually an awesome tool - saved me sooo many hours

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