如何发送对获取API的响应

Question

I am using fetch API to send data to my POST request...

fetch('http://localhost:8080/validation', {
    method:'POST',
    headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json'
    },
    body: JSON.stringify({
        email:this.state.email,
        password:this.state.password
    })
})
.then((response) => response.json())
.then((responseJson) => {
    console.log("response");
})
.catch(function(error) {
    console.log(error);
})

Simple enough, just sending email and password to POST handler. It is received and saved without error, but now I want to send back a custom response.

At the moment, my response throws an error. My Post handler looks as follows...

func Validate(rw http.ResponseWriter, req *http.Request, _ httprouter.Params) {

    decoder := json.NewDecoder(req.Body)

    var creds credentials

    err := decoder.Decode(&creds)

    if err != nil {
        panic(err)
    }
    ...

I do not know how to send a response. I'm assuming I need to encode to json first and then send it. But how exactly do I send it?

Let's say I want to return a string "success", do I need to return it? Or use fmt.Println()?

Answer 1

You write your response to to the http.ResponseWriter. For example:

func Validate(rw http.ResponseWriter, req *http.Request, _ httprouter.Params) {

    decoder := json.NewDecoder(req.Body)

    var creds credentials

    err := decoder.Decode(&creds)

    if err != nil {
        panic(err)
    }

    // rw is the HTTP response writer.
    fmt.Fprintf(rw, "success")
}