将模型对象从控制器返回到 Ajax jquery 在 Spring mvc 中不起作用

Question

I am trying to return a model object from spring mvc controller back to jquery ajax method but it is returning blank as the response

jsp:

$( "#dialog-link10" ).click(function( event ) {
var appname= $("#dialog-link10").text();
alert(appname);
if(appname == 'RS Applications') {
$.ajax({
    type : "GET",
    url : 'abc.html',
    dataType: 'JSON' ,
    data: 
        {"id" : $("#dialog-link10").text()}
    ,
    success : function(data) {
        alert('success')
        alert('data')

    }
});}

controller:

@RequestMapping(method=RequestMethod.GET, value="/abc")
@ResponseBody
public  Model helloWorld2( @RequestParam("id") String id, Model model) {

    System.out.println("*****"+id);

    List <String> list1=new ArrayList<String>();
    List <String> list2=new ArrayList<String>();

        System.out.println("here");

        list1.add("abc");
        list1.add("abc2");
        list1.add("abc3");
        list1.add("abc4");

        model.addAttribute("list1", list1);

        return model;
        }

This is not generating success alert as well. Please suggest

Answer 1

Your method should return directly the list, as a json, no need to put it in the model and return the model. Also check if you have an error in your callback ajax.

Answer 2

You are specifying dataType: 'JSON' in your ajax call, but you are not converting your response object (model) to json in your controller.

From the jQuery ajax documentation for dataType setting:

The type of data that you're expecting back from the server. If none is specified, jQuery will try to infer it based on the MIME type of the response (an XML MIME type will yield XML, in 1.4 JSON will yield a JavaScript object, in 1.4 script will execute the script, and anything else will be returned as a string)

You'll probably want to reference a json serializer (unless you want to write your own) - but the important part is serializing your model to json in your response. For example (using json-io ):

String jsonModel = JsonWriter.objectToJson(model);
return jsonModel;

You can then access the string array contained in your json response object in the following way:

success : function(data) {
     for (i = 0; i < data.list1.length; i++){
          alert(data.list1[i]);
     }
}

And a fiddle example for reading json objects

Answer 3

I met this problem and it took me several hours to find out the problem.
Just remove "Model model" from your parameter.
Use a Map<String, String> or Map<String, Object> instead.

Answer 4

Try adding the produces = MediaType.APPLICATION_JSON to the RequestMapping annotation

@RequestMapping(method=RequestMethod.GET, value="/abc", produces = MediaType.APPLICATION_JSON)

Also, you may not need the Model paramater in the method.