json sending null value to controller

Question

I am validating a form using jquery.validate.js and I need to identify duplicate entries, for this I am using custom method i.e:

jQuery.validator.addMethod("uniqueName", function(name, element) {
    var response;
    $.ajax({
        type: "POST",
        dataType : "json",
        url:"${pageContext.request.contextPath}/company/getDuplicate",
        data:"name="+name,
        async:false,
        success:function(data){
            response = data;
        },
        error: function (data) {
            alert(request.responseText);
        }
    });
}, "Name is Already Taken");

in rules section:

rules : {
    name : {
        required : true,
        uniqueName : true
    }
},
errorElement : "span",
messages : {
    name : {
        required : "Name Is Required"
    }
}

this is my JSP code:

<label>Name:</lable>
<form:input path="name"></form:input>

It's hitting for specified url but Json sending null value to the method

this is my controller method:

@RequestMapping(value = "/company/getDuplicate", method = RequestMethod.POST, headers = "Accept=*/*")
     public @ResponseBody void getTitleList(HttpServletRequest request, HttpServletResponse response) {
    
        JSONObject json = new JSONObject();
        String data = ((String)json.get("name"));
        List<Company> matched = companyService.getDuplicate(data);
        if (matched != null && !"".equals(matched)) {
            json.put("name", "present");
            System.out.flush();
        }
        else {
            json.put("name", "notPresent");
            System.out.flush();
        }
    }

what I want is:

1. how to send the value of the text box to the controller (Json sending null in my case).
2. In the above method, I don't think 'if statement have write condition' because when 'name' does not exist in the database then 'matched' variable shows like this => []

Please help me with this issues. Thanks in advance.

Answer 1

Modify your code as below:

$.ajax({
  type: "POST",
  dataType : "json",
  url:"${pageContext.request.contextPath}/company/getDuplicate",
  data:{"name":name},
  async:false,
  success:function(data) {
    response = data;
  },
  error: function (data) {
    alert(request.responseText);
  }
});

and Modify your controller handler as
Notice the commented first two lines and addtional @RequestParam(value="name") String name in method signature

@RequestMapping(value = "/company/getDuplicate", method = RequestMethod.POST, headers = "Accept=*/*")
     public @ResponseBody void getTitleList(@RequestParam(value="name") String name,HttpServletRequest request, HttpServletResponse response) {

        //JSONObject json = new JSONObject();
        //String data = ((String)json.get("name"));
        List<Company> matched = companyService.getDuplicate(name);
        if (matched != null && !"".equals(matched)) {
            json.put("name", "present");
            System.out.flush();
        } else {
            json.put("name", "notPresent");
            System.out.flush();
        }
    }