JQuery/AJAX call is not hitting Spring MVC controller

Question

I am trying to verify username and other fields while creating a change password page.The problem is AJAX call in Jquery script is not hitting my controller.i tried giving hard coded path also in url field of the ajax request. Below is my Script

this checkUname function is triggering on onblur event from one of the input field.

 <script type="text/javascript">
        function checkUname() 
            {
                // get the form values

                var uName = $('#username').val();
                var secQues = $('#secQues').val();
                var secAns = $('#secAns').val();

                var dataObject = JSON.stringify({
                                                    'uName'  : uName,
                                                    'secQues': secQues,
                                                    'secAns' : secAns
                                                });
             $.ajax({
                    url:"validateCredentials.do" ,
                    type: "POST" ,
                    data: dataObject ,
                    contentType: "application/json; charset=utf-8" ,
                    dataType : 'json' ,                 
                    success: function(response)
                                                {
                                                 alert(response);                           
                                                } ,
                    error: function()
                                        {
                                        alert('Error fetching record.... Sorry..');
                                        }
                    }); 
         }
        </script>

This is my MVC controller

    @Controller
public class ArsController 
{
    @RequestMapping(value="validateCredentials.do", method = RequestMethod.POST)
    public String changePass(@RequestParam("uName") String uName ,@RequestParam("secQues")String secQues,
                                   @RequestParam("secAns") String secAns)
    {
        System.out.println("AJAX request");
        Users dummyUSer = null;
        String msg = null;

                try 
                {
                    dummyUSer = servObj.findUser(uName);
                } 
                catch (ArsException e) 
                {
                    System.out.println("error occurred while validating user data during password change");
                    e.printStackTrace();
                }

                if(dummyUSer == null)
                {
                    msg = "No user exists with this username";
                }

                else
                {
                    if(!secQues.equals(dummyUSer.getSecQues()))
                    {
                        msg = "Security question is not correct";
                    }
                    else
                    {
                        if(!secAns.equals(dummyUSer.getSecAns()))
                        {
                            msg = "Security answer does not match";
                        }
                    }
                }

        return msg;
    }

Answer 1

Instead of using RequestParam in controller, you should use String. Because when we are posting JSON data it will not come as individual parameters in Request, instead it will be received as String in your controller. Once you get the String convert it to JSON object and then get your values accordingly.