How to bind json stringify data in golang custom struct type?

Question

js ajax

$.ajax({
    type: "POST"
    , url : url
    , data : JSON.stringify('{"nowBlockPositionX":3,"nowBlockPositionY":0,"nowBlock":{"O":0}}')
})

go custom struct

type demo struct {
    nowBlockPositionX  int                `form:"nowBlockPositionX" json:"nowBlockPositionX"`
    NowBlockPositionY  int                `form:"nowBlockPositionY" json:"nowBlockPositionY"`
    NowBlock           map[string]int     `form:"nowBlock" json:"nowBlock" query:"nowBlock"`
}

don't binding this

demo := new(demo)
if err := c.Bind(demo); err != nil {
    c.Logger().Error(err)
}

Possible duplicate of [JSON and dealing with unexported fields](https://stackoverflow.com/questions/11126793/json-and-dealing-with-unexported-fields) — Jonathan Hall, Nov 16 '18 at 09:23
duplicate a similar question is asked here https://stackoverflow.com/questions/61919830/go-gin-get-request-body-json/70077055#70077055 — Ali Bayatpour, Jun 12 '22 at 13:41

novalagung · Answer 1 · 2018-11-16T10:04:40.360

First, fix the demo struct. The field in the struct need to be exported. Just change the first character of each field to be in uppercase.

Then remove the form: and query: tags. You only need the json: tag.

type demo struct {
    NowBlockPositionX  int                `json:"NowBlockPositionX"`
    NowBlockPositionY  int                `json:"NowBlockPositionY"`
    NowBlock           map[string]int     `json:"NowBlock"`
}

There are also few problems appear on your javascript code, on the $.ajax statement.

Do this two things:

Set the content type header to application/json.
Remove the JSON.stringify() since your data already in string.

Working code:

$.ajax({
    url : url,
    type: "POST",
    dataType: "json",
    contentType: "application/json",
    data: '{"nowBlockPositionX":3,"nowBlockPositionY":0,"nowBlock":{"O":0}}'
 })

nit-pick: the json tags are there, and your tags are incorrect (start with capital `N`). In your example, the JSON tags are actually not needed, default behaviour is to map JSON onto field names directly anyway — Elias Van Ootegem, Nov 16 '18 at 11:44

How to bind json stringify data in golang custom struct type?

1 Answers1