How to send data to spring boot method using FETCH API

Question

I am exploring fetch api and want to send some for date to a spring boot method, but it is throwing 400 error

JS code

let fetchConfig = {
            method : params.method || 'GET',
            body : params.body
        };
        return fetch(_url,fetchConfig).then(function (response) {
            if (!response.ok) {
                throw Error(response.statusText);
            }
            else {
                return response.json();
            }
        }).then(function (data) {
            return data;
        }).catch(function (error) {
            return error;
        })

Spring boot method

@RequestMapping(value = "/validate",method = RequestMethod.POST,produces = MediaType.APPLICATION_JSON_VALUE)
    public  @ResponseBody ValidateUserModel validateUser(@RequestParam("userName") String userName, @RequestParam("password") String pass){
        System.out.println("--- test");
        ValidateUserModel validateUserModel = new ValidateUserModel();
        validateUserModel.setUserName("Test");
        validateUserModel.setPassWord("Test 2");
        return  validateUserModel;
    }

This is how fetchConfig looks like

body:{userName: "awdaw", password: "awdawd"}
method:"POST"
password:"test"
url:"test"
userName:"awdaw"
__proto__:Object

Preview of the values send from java class

error:"Bad Request"
exception:"org.springframework.web.bind.MissingServletRequestParameterException"
message:"Required String parameter 'userName' is not present"
path:"/validate"
status:400
timestamp:1504771336175

The error says Required String parameter 'userName' is not present but the fetchConfig have the required key

Answer 1

Your Java code expects request params, so the expected url should be something like .../validate?username=<someValue>&password=<otherValue> , but your js is sending that in the body (which is a better option, sending user and password as part of the URL is not secure at all).

You could change your Java code to something like

@RequestMapping(value = "/validate",method = RequestMethod.POST,produces = MediaType.APPLICATION_JSON_VALUE)
public  @ResponseBody ValidateUserModel validateUser(@RequestBody User user){
    System.out.println("--- test");
    ValidateUserModel validateUserModel = new ValidateUserModel();
    validateUserModel.setUserName(user.getUserName());
    validateUserModel.setPassWord(user.getPassword());
    return validateUserModel;
}

Where User is just a bean with password and userName as attributes.

Answer 2

Try Using @RequestBody annotation.

@RequestMapping(value = "/validate",method = RequestMethod.POST,produces = MediaType.APPLICATION_JSON_VALUE)
public  @ResponseBody ValidateUserModel validateUser(@RequestBody User user){
    System.out.println("--- test");
    ValidateUserModel validateUserModel = new ValidateUserModel();
    validateUserModel.setUserName(user.getUserName());
    validateUserModel.setPassWord(user.getPassword());
    return validateUserModel;
}

and the request should look like:

  let data = {userName: "awdaw", password: "awdawd"};
    fetch{ url, {
      body: JSON.stringfy(data)
      method:"POST"
      headers: {
               "Content-Type": "application/json",
           },
     }).then(
            response =>  {
                return response.json();
            }