CODEWITHSUNDEEP
javajsonangularspringspring-boot
Shephard
Shephard

Reputation: 127

Spring / Angular 7 POST method requestparameter is null

I would like to send datas (in json form) from frontend to backend using POST, but requestparameter is null.

Angular:

this.http.post('api/example', { mydata: JSON.stringify(data) },
 { "headers": { header: "text/html;charset=UTF-8" } }).subscribe(Response => console.log(Response);
});

JSON.stringify(data) looks like this:

[
  ["num1","num2","num3","num4","num5", "num6"],
  ["test6","test2","test1","test5","test4", "test3"]
]

This is just an example, the data will be dynamic, so sometimes I will have more or less columns and rows.

Spring backend:

@RequestMapping(value = "/api/example", method = RequestMethod.POST)
public @ResponseBody void postExample(HttpServletRequest request, HttpServletResponse response)
        throws IOException {

    HttpSession session = request.getSession();

    response.setContentType("text/html");
    response.setCharacterEncoding("UTF-8");
    request.setCharacterEncoding("UTF-8");

    String mydata = request.getParameter("mydata");
    System.out.println(mydata);
    ...
}

mydata is null, when I print out. I don't know why. What I tried:

I would like to use "getParameter" instead of using @RequestBody annotation.

How can I get the json data from frontend and use it in backend?

Edit: Originally I didn't want to use @RequestBody, but if I want to use it, how can I use it for getting these json arrays?

Upvotes: 0

Views: 592

Answers (2)

Marc Stroebel
Marc Stroebel

Reputation: 2357

for using @RequestBody you'll need a Java data structure matching your JSON, e.g. a nested array

@PostMapping(path="/api/example")
public void postExample(@RequestBody ArrayList<ArrayList<String>> body) {

    //....

}

Test case (from question above)

[
  ["num1","num2","num3","num4","num5", "num6"],
  ["test6","test2","test1","test5","test4", "test3"]
]

Upvotes: 1

Vladimir Stanciu
Vladimir Stanciu

Reputation: 1536

You need to use .getReader(), instead of the .getParameter() method, since you need to retrieve the body of the request not some parameter.

Upvotes: 1

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