How to post a request to get cookie values and post new request by the previously obtained cookie By using Go language?

How to post a request to get cookie values and post new request by the previously obtained cookie By using Go language

here first post request is generating a variable cookie in the form [SID=pcmPXXx+fidX1xxxX1cuK; Path=/; HttpOnly; SameSite=Strict]"

but i can't send this cookie to another post request (getting error).

sample go file with comments

package main
import (
"fmt"
"log"
"strings"
"net/http"
"io/ioutil"
"net/http/cookiejar"
)
var client http.Client
func init() {
jar, err := cookiejar.New(nil)
if err != nil {
log.Fatalf("Got error while creating cookie jar %s", err.Error())
}
client = http.Client{
Jar: jar,
}
}
func main() {
urlx := "http://localhost:8080/api/v2/auth/login"
methodx := "POST"
payloadx := strings.NewReader(`username=admin&password=strongadmin`)
client := &http.Client {
}
reqx, err := http.NewRequest(methodx, urlx, payloadx)
if err != nil {
fmt.Println(err)
return
}
reqx.Header.Add("Referer", "http://localhost:8080/")
reqx.Header.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36")
reqx.Header.Add("Content-type", "application/x-www-form-urlencoded; charset=UTF-8")
resx, err := client.Do(reqx)
if err != nil {
fmt.Println(err)
return
}
defer resx.Body.Close()
cookie := resx.Cookies()
fmt.Println(cookie)
bodyx, err := ioutil.ReadAll(resx.Body)
if err != nil {
fmt.Println(err)
return
}
fmt.Println(string(bodyx))
//second request start here 
// this var cookies is a dummy cookie that i manually written,
// i need to replace the below variable 'cookies' to previously obtained variable 'cookie' without error
cookies := &http.Cookie{
Name: "SID",
Value: "PW16gD0Ja0OqixXeqpQle1WC/OK19tj+",
MaxAge: 300,
}
url := "http://localhost:8080/api/changes"
method := "POST"
payload := strings.NewReader(`json=%7B%data=valuex%22%3A%22300%22%7D`)
clientx := &http.Client {
}
req, err := http.NewRequest(method, url, payload)
if err != nil {
fmt.Println(err)
return
}
//  req.Header.Add("Accept", "text/javascript, text/html, application/xml, text/xml, */*")
req.Header.Add("Referer", "http://localhost:8080/")
req.Header.Add("X-Requested-With", "XMLHttpRequest")
req.Header.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36")
req.Header.Add("Content-type", "application/x-www-form-urlencoded; charset=UTF-8")
req.AddCookie(cookies)
res, err := clientx.Do(req)
if err != nil {
fmt.Println(err)
return
}
defer res.Body.Close()
body, err := ioutil.ReadAll(res.Body)
if err != nil {
fmt.Println(err)
//second request end here
} 

In first request You're getting cookies as:

cookie := resx.Cookies()

• which is slice of Cookie struct []*http.Cookie

then if You want to use them in next request do loop over them and add:

for _, c := range cookie {
  req.AddCookie(c)
}

check this example