400 error getting oauth user token in golang? - api

Question

I tried to get the ebay user token.
I've alreay gotten auth code in ebay, but can't get user token with auth code.
Code is following:
status := ctx.UserValue("status").(string)
applicationToken := string(ctx.QueryArgs().Peek("code"))
log.Println("ApplicationToken: ", applicationToken)
log.Println("Status: ", status)
if status == "declined" {
    fmt.Printf("User doesn't give permission. Go back to your dashboard.")
    ctx.Redirect("/dashboard", fasthttp.StatusSeeOther)
}
//var appConfig = config.Config()
client := &http.Client{}
applicationTokenURLEncoded, _ := url.Parse(applicationToken)
body := url.Values{
    "grant_type": {"authorization_code"},
    "code": {applicationTokenURLEncoded.String()},
    "redirect_uri": {Runame},
}
reqBody := bytes.NewBufferString(body.Encode())
log.Println("Reqbody: ", reqBody)
req, _ := http.NewRequest("POST", "https://api.sandbox.ebay.com/identity/v1/oauth2/token", reqBody)
authorization := “AppID” + ":" + “CertID”
authorizationBase64 := base64.StdEncoding.EncodeToString([]byte(authorization))
req.Header.Add("Authorization", "Basic "+authorizationBase64)
req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
log.Println("Body: ", req)
resp, _ := client.Do(req)
log.Println("resp: ", resp)
log.Println("ResBody: ", resp.Body)
And the error is like that:
Bad Request 400

Answer 1

I looks like the message isn't formed correctly (which is why the server returns 400).
When you're setting your headers you write:
req.Header.Add("Authorization", "Basic "+authorizationBase64)
req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
Golang has a nice built in way to add Authorization to a Header: SetBasicAuth, which is a method of http.Request.
func (r *Request) SetBasicAuth(username, password string)
SetBasicAuth sets the request's Authorization header to use HTTP Basic Authentication with the provided username and password.
With HTTP Basic Authentication the provided username and password are not encrypted.
So instead of setting the Authorization Header manually, you could try:
req.SetBasicAuth("AppID”, “CertID”)
You were using something called CertID, but I think you meant ClientId and ClientSecret -- respectively user and password
I don't know if this is the cause of your problem :). One way to help find out, is consistent error checking, see your line:
applicationTokenURLEncoded, _ := url.Parse(applicationToken)