Golang Struct as Payload for POST Request - http

Question

New to golang. I'm trying to make a POST request to an auth endpoint to get back a token for authing further requests. Currently the error I'm getting is missing "credentials". I've written the same logic in Python so I know what I am trying to do is what the system is expecting.
package main
import (
"bufio"
"bytes"
"encoding/json"
"fmt"
"io/ioutil"
"log"
"net/http"
"net/http/cookiejar"
"os"
)
type Auth struct {
Method string `json:"credentials"`
Email string `json:"email"`
Password string `json:"password"`
Mfa string `json:"mfa_token"`
}
func main() {
reader := bufio.NewReader(os.Stdin)
fmt.Print("Enter Email: ")
e, _ := reader.ReadString('\n')
fmt.Print("Enter Password: ")
p, _ := reader.ReadString('\n')
fmt.Print("Enter 2FA Token: ")
authy, _ := reader.ReadString('\n')
auth := Auth{"manual", e, p, authy}
j, _ := json.Marshal(auth)
jar, _ := cookiejar.New(nil)
client := &http.Client{
Jar: jar,
}
req, err := http.NewRequest("POST", "https://internaltool.com/v3/sessions", bytes.NewBuffer(j))
if err != nil {
log.Fatal(err)
}
req.Header.Add("Accept-Encoding", "gzip, deflate, br")
res, err := client.Do(req)
if err != nil {
log.Fatal(err)
}
defer res.Body.Close()
body, _ := ioutil.ReadAll(res.Body)
s := string(body)
if res.StatusCode == 400 {
fmt.Println("Bad Credentials")
fmt.Println(s)
return
}
}
The question is - am I properly marshalling the AUTH struct into JSON and adding it appropriately to the POST request? As the API is not even seeing the credentials key in the JSON I think I must be doing something wrong. Anything helps.

Answer 1

Here's a minimum viable example of using json.Marshal to convert a Struct to a JSON object in the context of a POST request.
Go's standard libraries are fantastic, there is no need to pull in external dependencies to do such a mundane thing.
func TestPostRequest(t *testing.T) {
// Create a new instance of Person
person := Person{
Name: "Ryan Alex Martin",
Age: 27,
}
// Marshal it into JSON prior to requesting
personJSON, err := json.Marshal(person)
// Make request with marshalled JSON as the POST body
resp, err := http.Post("https://httpbin.org/anything", "application/json",
bytes.NewBuffer(personJSON))
if err != nil {
t.Error("Could not make POST request to httpbin")
}
// That's it!
// But for good measure, let's look at the response body.
body, err := ioutil.ReadAll(resp.Body)
var result PersonResponse
err = json.Unmarshal([]byte(body), &result)
if err != nil {
t.Error("Error unmarshaling data from request.")
}
if result.NestedPerson.Name != "Ryan Alex Martin" {
t.Error("Incorrect or nil name field returned from server: ", result.NestedPerson.Name)
}
fmt.Println("Response from server:", result.NestedPerson.Name)
fmt.Println("Response from server:", result.NestedPerson.Age)
}
type Person struct {
Name string `json:"name"`
Age int `json:"age"`
}
// NestedPerson is the 'json' field of the response, what we originally sent to httpbin
type PersonResponse struct {
NestedPerson Person `json:"json"` // Nested Person{} in 'json' field
}

Answer 2

As http.Client is relatively a low-level abstraction, gorequest(https://github.com/parnurzeal/gorequest) as an alternative is strongly recommended.
headers, queries, and body can be posted in any type, which is a bit more like what we often do in Python.