[FIXED] How to prevent a 400 code being returned from java server side when you expect an empty result?

Issue

I have an ajax call to a server side java servlet and a null response is quite valid. However, I also get a 400 error code. The issue with this is that the 400 errors are filling up my report-uri log making it hard to find any 'real' errors. Is there a way to prevent the 400 code.

The ajax call is:

      $.ajax({
            url : 'NewsDispView',
            data : {
                ssAccountLevel : sessionStorage.getItem('ssAccountLevel'),
                ssAccountID : sessionStorage.getItem('ssAccountID'),
                ssGroupID: sessionStorage.getItem('ssGroupID'),
                ssGroupSection: sessionStorage.getItem('ssGroupSection'),
            },
            type : 'POST',
            cache: false,
        })
        .fail (function(jqXHR, textStatus, errorThrown) {
    //      alert(jqXHR.responseText);
            if(jqXHR.responseText.includes('No News')){
                alert("No news");
            }else{
                alert("News");
            }
            var marquee = "<span class='glyphicon glyphicon-forward'>";
            marquee += " No notices ";
            marquee += "<span class='glyphicon glyphicon-forward'>";
            $("#newsMarquee").empty();
            $('#newsMarquee').append(marquee);
        })
        .done(function(responseJson1a){
            // JSON response to populate the activities table
            dataType: "json";
    
            //alert(JSON.stringify(responseJson1a));
            
            //do stuff
        })

The servlet return is:

    if (newsList == null || newsList.isEmpty()) {
        response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No News.");
    } else {
        String json = new Gson().toJson(newsList);
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        response.getWriter().write(json);
    }

Solution

You can pass your error message as well in JSON format to your ajax call . So , generate your json then pass it like below :

if (newsList == null || newsList.isEmpty()) {
   String json = new Gson().toJson(yourjson);
 } else {
   String json = new Gson().toJson(newsList);
 }
 response.setContentType("application/json");
 response.setCharacterEncoding("UTF-8");
 response.getWriter().write(json);

Then , check in your ajax code if the response has the key or not i.e : error and change your ajax logic accordingly.

Answered By - Swati
Answer Checked By - Timothy Miller (JavaFixing Admin)