ajax returning null for large amount of data from spring controller

Question

I try to return data from controller to AJAX success() callback. This code perfectly works for 100,000 objects. But when I increase size of list to 1 million objects, it goes to success() callback, but returning null as response. Could you help me with finding the way to return 1 mln of objects?

 A.$.ajax({
            url: 'getData',
            dataType: 'json',
            success: function (response) { 
            alert(response)
            }

@RequestMapping("/getData")
public  @ResponseBody
 void download(HttpServletResponse response ) throws IOException, JSONException
 {
  List <Objects> list = getListFromService();
  response.setContentType("application/json"); 
  PrintWriter out = response.getWriter();  
  ObjectMapper mapper = new ObjectMapper();
  String jsonString = mapper.writeValueAsString(list);
  out.print(jsonString);
  out.flush(); 
 }

As an aside, why would you want to return a million objects at once? How would you present that much data to the user? — nnnnnn, Sep 04 '17 at 04:03
@nnnnnn I would like to put them all into csv file for user to download. I know that I can do at server side in controller as well. Just wanted try both approaches and figure out what is the best way. But I think, I'll stay with server-side file generation — WomenWhoCode, Sep 04 '17 at 04:07
perhaps your server is limiting the response size - check the browser **developer** tools console and network tab for any indication of this — Jaromanda X, Sep 04 '17 at 04:10

score 0 · Answer 1 · answered Sep 04 '17 at 04:43

0

Your method is annotated with @ResponseBody but it's return type is void. Try to return your List directly, and let Spring handle the JSON processing for you:

@RequestMapping("/getData")
public @ResponseBody List<Objects> download( ) {
    return getListFromService();
}

answered Sep 04 '17 at 04:43

Johannes Erchen

134
8

I tried this too. It works for 100 000 records, but not for 1 million. Returning null for 1 million – WomenWhoCode Sep 04 '17 at 05:17

score 0 · Answer 2 · answered Sep 04 '17 at 05:02

0

There is a limit set by server and the spring too probably. Check this link.

In such case you should mostly see error in the logs for the limit being exceeded.

answered Sep 04 '17 at 05:02

Sandeep Shukla

1
2

ajax returning null for large amount of data from spring controller

2 Answers2