POST call failing with JSON [duplicate] - go

Question

This question already has an answer here:
Unmarshalling json in golang
(1 answer)
Closed 4 years ago.
I have an API which accepts a request body like this:
The content-type is application/json.
{
"firstname": "foo",
"surname": "bar",
"age": 10,
"group":"test"
}
The request goes through when I use a client like Postman.
However, the same request fails from Go:
type Student struct {
firstname string
surname string
age int
group string
}
student:= Student{"foo", "bar", 10, "test"}
b, err := json.Marshal(student)
rest := restCall("POST", "http://api", b, "xyz123")
func restCall(method string, url string, body []byte, token string) {
req, _ := http.NewRequest(method, url, bytes.NewReader(body))
req.Header.Add("Authorization", token)
req.Header.Add("content-type", "application/json")
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
}
I get an internal HTTP 500 error stating :
Mandatory parameter 'group' is missing.
But, I did pass it as you can see from my code.

Answer 1

Your code has several issues:
1. Structure must have public fields and fields should be tagged. Then it will be serialized properly:
type Student struct {
Firstname string `json:"firstname"`
Surname string `json: "surname"`
Age int . `json: "age"`
Group string `json: "group"`
}
2. Never ignore errors returned by method call. So you will not miss issues in your code:
b, err := json.Marshal(student)
if err != nil {
fmt.Println(err)
}
And the same after calls of NewRequest and DefaultClient.Do