I have a Sprng MVC application, and I am using datatables to populate various tables in the app. I am currently working on a page that has several tables, that pull in data at various points throughout the workflow on the page, based on session attributes.

When the page initially loads, one of these tables will have no data, since it relies on a session attribute for the data to be retrieved.

I am attempting to place a conditional statement in that GET method, which essentially states, "if this session attribute exists, build the table using this data." I am not sure what to use as the "else" for this conditional.

At this point, when the page initially loads, I simply get a pop-up message stating that I have given an invalid json response. Right now, I am simply returning "" since I'm not really sure what to use.

Once I have the session attribute, the table loads with all the correct data.

So basically, I'd just like to know if there is a String that I can return in my method in the "else" conditional that will serve as a valid json response.

TO summarize: in my javascript datatables script, I have the parameter,

 "ajax" : "getThisTableData.htm"

Then, in my controller I have,

  value = "/getThisTableData.htm",  method = RequestMethod.GET
            public String getStuff (HttpServletRequest req) throws IOException{
                 if (null != thisSessionAttribute){
                      do JSON stuff;

                      return json;
                 }
                 else {
                      return "";

So that "else" return value is what I am looking to fix.