json: cannot unmarshal string into Go value of type main.test_struct

Question

I receive a json from an api and i try to unmarshall it, and i don't understand the error that i get :

json: cannot unmarshal string into Go value of type main.test_struct

Here is the json that i get :

INFO: 2017/02/03 17:47:53 ApiRecordGeo.go:66: "{\"lat\":48.892423,\"lng\":2.215331,\"acc\":1962}"

here is my code :

type test_struct struct {
    Lat float32 `json:"lat"`
    Lng float32  `json:"lng"`
    Acc int       `json:"acc"`

}

func postGeo(w http.ResponseWriter, r *http.Request) {
        var t test_struct;
    err := json.NewDecoder(r.Body).Decode(&t)
    if err != nil {
        panic(err)
    }
/*  hah, err := ioutil.ReadAll(r.Body);

    if err != nil {
        panic(err)
    }
    Info.Println(hah)
    s := string(hah)
    Info.Println(s)
    Info.Println(t.Lat)*/
    defer r.Body.Close()
    Info.Println("POST FP")
    w.Header().Set("Access-Control-Allow-Origin", "*")
    fmt.Fprintf(w, "200")
}

If anyone have any clue ... Thanks and regards

edit : Second version still the same error :

type test_struct struct {
    Lat float32 `json:"lat"`
    Lng float32  `json:"lng"`
    Acc int       `json:"acc"`

}

func postGeo(w http.ResponseWriter, r *http.Request) {
        var t test_struct;
    err := json.NewDecoder(r.Body).Decode(&t)
    if err != nil {
        panic(err)
    }
/*  hah, err := ioutil.ReadAll(r.Body);

    if err != nil {
        panic(err)
    }
    Info.Println(hah)
    s := string(hah)
    Info.Println(s)
    Info.Println(t.Lat)*/
    //defer r.Body.Close()
    fmt.Println("POST FP")
    w.Header().Set("Access-Control-Allow-Origin", "*")
    fmt.Fprintf(w, "200")
}

edit ter : here si the code that send the data (in javascript)

var url = "https://www.googleapis.com/geolocation/v1/geolocate?key=666";
$.ajax({
    type: 'POST',
    url: url,
    crossDomain: true,
    success: function(data){
//success jsonp handler - assume content in data.response
        console.log(data);
        var long = data.location.lng ;
        var lat = data.location.lat;
        var params = {long:long, lat:lat};
        url_bis = "http://localhost:9280/post_geo/";
        $.ajax({
            type: 'POST',
            url: url_bis,
            crossDomain: true,
            data: params,
            dataType: 'jsonp',
            success: function(data2){
                console.log(data2);

            },
        });


    },
});

Is that the literal value you get in the body, quotes and all, or is it a value contained in a larger json body? If that's the case it's a string containing json, and you need to un-quote it. — Mr_Pink
– Mr_Pink, Commented Feb 3, 2017 at 17:18
@JimB this is the json there is no quote normally in the json that i get. The print is what i get when i uncomment the code to print the body — Bussiere
– Bussiere, Commented Feb 3, 2017 at 17:37
The error is specific, you are giving it a string, and if there are no quotes normally, then it will work. I don't know what Info.Println is doing to format arguments, may show the output via a plain fmt.Println so we can better guess what you're working with. (BTW, you don't need to call r.Body.Close) — Mr_Pink
– Mr_Pink, Commented Feb 3, 2017 at 17:47
Here's a simplified version: play.golang.org/p/_JrwAIxU9a Unfortunately it works just fine. May it be that you get in a body a string escaped twice? — Paweł Szczur
– Paweł Szczur, Commented Feb 3, 2017 at 17:52

Paweł Szczur · Accepted Answer · 2017-02-03 18:04:35Z

2

The tricky part is how the data is sent by a jQuery.ajax(). In a documentation you may find:

By default, data passed in to the data option as an object (technically, anything other than a string) will be processed and transformed into a query string, fitting to the default content-type "application/x-www-form-urlencoded".

Which means that data the script is sending looks more like:

lat=48.892423&lng=2.215331&acc=1962

answered Feb 3, 2017 at 18:04

Paweł Szczur

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