http.Post data-binary, curl equivalent in golang

Question

I'm trying to use net/http to post a json file to ElasticSearch. Normally in Curl I would do the following:

curl -XPOST localhost:9200/prod/aws -d @aws.json

In golang I've used an example but it has not worked. I can see it posting but something must be set incorrectly. I've tested the JSON file I am using and it's good to go.

Go code:

  target_url := "http://localhost:9200/prod/aws"
  body_buf := bytes.NewBufferString("")
  body_writer := multipart.NewWriter(body_buf)
  jsonfile := "aws.json"
  file_writer, err := body_writer.CreateFormFile("upfile", jsonfile)
  if err != nil {
    fmt.Println("error writing to buffer")
    return
  }
  fh, err := os.Open(jsonfile)
  if err != nil {
    fmt.Println("error opening file")
    return
  }
  io.Copy(file_writer, fh)
  body_writer.Close()
  http.Post(target_url, "application/json", body_buf)

Answer 1

If you want to read json from file then use .

jsonStr,err := ioutil.ReadFile("filename.json")
if(err!=nil){
    panic(err)
}

Simple way to post json in http post request.

    req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonStr))
    req.Header.Set("Content-Type", "application/json")

    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    fmt.Println("response Status:", resp.Status)
    body, _ := ioutil.ReadAll(resp.Body)
    fmt.Println("response Body:", string(body))

This should work

Answer 2

Note that you can Post with an io.Reader as the body:

file, err := os.Open("./aws.json")
resp, err := http.Post(targetUrl, "application/json", file)
// TODO: handle errors

This might work better than reading the file contents into memory first, especially if the file is very large.