How do I send a JSON string in a POST request in Go

I tried working with Apiary and made a universal template to send JSON to mock server and have this code:

package main

import (
    "encoding/json"
    "fmt"
    "github.com/jmcvetta/napping"
    "log"
    "net/http"
)

func main() {
    url := "http://restapi3.apiary.io/notes"
    fmt.Println("URL:>", url)

    s := napping.Session{}
    h := &http.Header{}
    h.Set("X-Custom-Header", "myvalue")
    s.Header = h

    var jsonStr = []byte(`
{
    "title": "Buy cheese and bread for breakfast."
}`)

    var data map[string]json.RawMessage
    err := json.Unmarshal(jsonStr, &data)
    if err != nil {
        fmt.Println(err)
    }

    resp, err := s.Post(url, &data, nil, nil)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("response Status:", resp.Status())
    fmt.Println("response Headers:", resp.HttpResponse().Header)
    fmt.Println("response Body:", resp.RawText())

}

This code doesn't send JSON properly, but I don't know why. The JSON string can be different in every call. I can't use Struct for this.

Solution 1:

I'm not familiar with napping, but using Golang's net/http package works fine (playground):

func main() {
    url := "http://restapi3.apiary.io/notes"
    fmt.Println("URL:>", url)

    var jsonStr = []byte(`{"title":"Buy cheese and bread for breakfast."}`)
    req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonStr))
    req.Header.Set("X-Custom-Header", "myvalue")
    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)
    fmt.Println("response Headers:", resp.Header)
    body, _ := ioutil.ReadAll(resp.Body)
    fmt.Println("response Body:", string(body))
}

Solution 2:

you can just use post to post your json.

values := map[string]string{"username": username, "password": password}

jsonValue, _ := json.Marshal(values)

resp, err := http.Post(authAuthenticatorUrl, "application/json", bytes.NewBuffer(jsonValue))

Solution 3:

If you already have a struct.

import (
    "bytes"
    "encoding/json"
    "io"
    "net/http"
    "os"
)

// .....

type Student struct {
    Name    string `json:"name"`
    Address string `json:"address"`
}

// .....

body := &Student{
    Name:    "abc",
    Address: "xyz",
}

payloadBuf := new(bytes.Buffer)
json.NewEncoder(payloadBuf).Encode(body)
req, _ := http.NewRequest("POST", url, payloadBuf)

client := &http.Client{}
res, e := client.Do(req)
if e != nil {
    return e
}

defer res.Body.Close()

fmt.Println("response Status:", res.Status)
// Print the body to the stdout
io.Copy(os.Stdout, res.Body)

Full gist.