golang hangs when using multipart/form-data

Question

I want to make an empty post request to telegram. The problem is if i close multipart once, it hangs forever:

 func main() {
    var requestBody bytes.Buffer
    multiPartWriter := multipart.NewWriter(&requestBody)
    multiPartWriter.Close()      // closing once
    req, _ := http.NewRequest("POST", "https://api.telegram.org/bot<telegram token>/getme", &requestBody)
    req.Header.Set("Content-Type", multiPartWriter.FormDataContentType())
    client := &http.Client{}
    client.Do(req)
}

But if i close the multipart twice it works. Can anyone explain why this happens?

Hi, what exactly is your problem? Tested your snippet, it works. https://play.golang.org/p/_SiH1s8rkQw — Tobias Theel, Nov 02 '21 at 10:09
hi @TobiasTheel you need to change with a valid token to see the problem — gcoder, Nov 02 '21 at 10:13
I don't have any telegram tokens, so I cannot help unless you could provide a reproducible example — Tobias Theel, Nov 02 '21 at 10:20
The response is: {"ok":true,"result":{"id":,"is_bot":true,"first_name":"Test","username":"can_join_groups":true,"can_read_all_group_messages":false,"supports_inline_queries":false}} — Tobias Theel, Nov 02 '21 at 10:44

Tobias Theel · Accepted Answer · 2021-11-02T10:59:12.003

I just checked the Telegram API.

I guess the general problem is, that you use a buffer that is not initialized. You don't need the buffer, you don't need any payload in the request. You can just pass nil as request data. Like this:

func main() {
    req, err := http.NewRequest("POST", "https://api.telegram.org/bot<token>/getme", nil)
    if err != nil {
        panic(err)
    }

    client := &http.Client{}

    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }

    result, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        panic(err)
    }

    println(string(result))
}

I also recommend, that you check out the docs here this documentation lets you interactively try out the API, it can also generate the code for each request.

In order to generate Go code examples, you can click on the button at the upper right corner and chose your Go.

golang hangs when using multipart/form-data

1 Answers1