Is it possible to bind to map object of custom struct type?

Question

my question is, how to bind(auto binding?) custom structure type in a map object(variable)?

this is my custom struct type

type Tetris struct {
    ... ...
    NowBlock           map[string]int     `form:"nowBlock" json:"nowBlock"`
    ... ...
}

this is my ajax code

 $.ajax({
     type : "POST"
     , url : "/game/tetris/api/control"
     , data : {
                "keyCode" : keyCode
                , "ctxWidth" : ctxWidth
                , "ctxHeight" : ctxHeight
                , "nowBlock" : {"O":0}
     } // also, i did JSON.stringify, but did not binding..
     , dataType : "json"
     , contentType : "application/json"
     }).done(function(data){
           ... ...
 });

and then, do not binding 'NowBlock'

tetris := new(Tetris)
if err := c.Bind(tetris); err != nil {
    c.Logger().Error(err)
}
fmt.Println(tetris.NowBlock)

the println result is ,

'map[]' //nil...

this is my full question link(GOLANG > How to bind ajax json data to custom struct type?)

please help me.

ps. thank you for answer me. I did like the answer. BUT, it does not working too.

First,

- No 'contentType : "application/json"'
- don't use JSON.stringify

 then, in go side, 
- fmt.println(tetris.KeyCode) // OK
- fmt.println(tetris.NowBlock) // NOT OK.. 'map[]'

Second,

- Use 'contentType : "application/json"'
- Use JSON.stringify

then, in go side, 
- fmt.println(tetris.KeyCode) // NOT OK.. '' (nil)
- fmt.println(tetris.NowBlock) // NOT OK.. 'map[]'

Third,

i remove the custom struct type Tetris NowBlock object's `form:nowBlock` literal, 
but is does not working too...

why not binding Custom structure type in a map object?

i'm so so sorry. i solve this question. the problem that is my go custom struct type have another custom struct type.

like this.

type Tetris struct {
    Common Common

    NowBlock           map[string]int     `json:"nowBlock"`
}

type Common struct {
    CtxWidth  int `json:"ctxWidth"`
    CtxHeight int `json:"ctxHeight"`

    KeyCode int `form:"keyCode" json:"keyCode"`
}

in this case, i did

 $.ajax({
 type : "POST"
 , url : "/game/tetris/api/control"
 , data : {
            "keyCode" : keyCode
            , "ctxWidth" : ctxWidth
            , "ctxHeight" : ctxHeight
            , "nowBlock" : {"O":0}
 } // also, i did JSON.stringify, but did not binding..
 , dataType : "json"
 , contentType : "application/json"
 }).done(function(data){
       ... ...

});

but, this is wrong! the correct is,

$.ajax({
    type : "POST"
    , url : "/game/tetris/api/control"
    , data : JSON.stringify({
        "Common" : {
            "keyCode" : keyCode
            , "ctxWidth" : ctxWidth
            , "ctxHeight" : ctxHeight
        }
        , "nowBlock" : {"O":0}
    })
    , dataType : "json"
    , contentType : "application/json"
}).done(function(data){
   ... ...

in json data, 'Common' struct type's data must have "Common" 'Key:value' map...

i'm very glade to your answers and attentions.

i'm sorry. That 'c' is context.( echo framework link > https://echo.labstack.com/guide/request) — gdk, Nov 21 '18 at 05:26

score 0 · Answer 1 · answered Nov 21 '18 at 06:11

0

Maybe you should remove struct tag 'form', when you use 'application/json' send data, 'form' tag is unused.
The program is going well when I just add 'json' tag, and if I add 'form' tag, echo uses the 'form' and get an error.

Hope this can help you.

answered Nov 21 '18 at 06:11

Laily

4,024
1
14
14

@gdk if you send js data with `content-type=application/json` ?, you can check is with this way. 1. if data send correct, ioutil.ReadAll(c.Request().Body), this should be the json data you had sent. 2. you have the correct struct to bind to the json data. 3. use the correct struct tag. Echo bind data by struct tag and content-type, tag json for `application/json`, tag form for `application/x-www-form-urlencoded`, tag query for parameters in url. There is my test code: https://goplay.space/#A70IHubaQIH – Laily Nov 22 '18 at 07:46
Tank you so much. i changed my ajax code. added code is 'application/json'. And end of my question, my mistake was custom struct type's object other custom struct type. That’s very kind of you! – gdk Nov 22 '18 at 08:51

score 0 · Accepted Answer · answered Nov 21 '18 at 06:14

0

There is no problem in your go code. Why echo .Bind() not able to retrieve the payload sent from AJAX is because the payload is not in JSON format.

On $.ajax you need to JSON.stringify() the data into JSON string format.

JSON.stringify({
    "keyCode" : keyCode
    , "ctxWidth" : ctxWidth
    , "ctxHeight" : ctxHeight
    , "nowBlock" : {"O":0}
})

Setting contentType into application/json will not automatically convert payload into JSON string. That's why JSON.stringy() is still required.

Full changes:

var payload = JSON.stringify({
    "keyCode": keyCode,
    "ctxWidth": ctxWidth,
    "ctxHeight": ctxHeight,
    "nowBlock": {
        "O": 0
    }
})

$.ajax({
    type: "POST",
    url: "/game/tetris/api/control",
    data: payload,
    dataType: "json",
    contentType: "application/json"
}).done(function(data) {
    ......
});

answered Nov 21 '18 at 06:14

novalagung

10,905
4
58
82

thank you. first, i was remove contentType in ajax, GO tetris.KeyCode > working // printing 'key code: 13..' but, tetris.NowBlock > don't working.. // pringing 'map[]' second, contentType: "application/json" and data: stringify({json..}) GO tetris.KeyCode > don't working // printing nil but, tetris.NowBlock > don't working.. // pringing 'map[]' – gdk Nov 21 '18 at 06:48
if you remove the `contentType`, the payload will sent with content type `application/x-www-form-urlencoded`. some array information will be unreadable – novalagung Nov 21 '18 at 06:50
sorry my comment was incorrect. so i edit my question(please read the end of question). – gdk Nov 21 '18 at 07:01

Is it possible to bind to map object of custom struct type?

2 Answers2