react native fetch not sending body content

Question

I am new to fetch in react native and followed this tutorial.
I am trying to send a json body to an private api server, I checked the server log and found out that the body content is empty.

Here is the code in react native

authenticateLogIn(){
    fetch('<URL>', {
          method: 'POST',
          header: {'Content-Type': 'application/json', 'Accept': 'application/json'},
          body: JSON.stringify({'username': '<username>', 'password':'<password>'})
        })
        .then((incoming) => incoming.json())
        .then((response) => {
          console.log(response.header);
          Alert.alert(JSON.stringify(response.body));
        })
        .done();

Answer 1

Maybe because it shoueld be headers? (with the s)

Answer 2

It might be because your JSON body isn't being parsed correctly. bodyParser https://github.com/expressjs/body-parser is part of the middleware that parses request bodies and needs to be configured.

req.body kept coming back empty for me until I added app.use(bodyParser.json() into server.js file. Make sure you import body-parser.