So I am still lost here. I have a form with a modal. The modal is used to "attach" a file. I want to temporarily store the file on the server then email it with rest of form input values when form is submitted. I am using this ajax call to post this to the server so that the whole form doesn't submit and refresh the page. But to save it via ajax call, I need to serialize the file and so then it is not saving correctly. I have multiple issues with this... one is that the document is saving as null and will not open, and I believe the reason is I do not know how to grab the name of the file. Document is usually used to create a new item in my sql database document table so by calling it this way I am getting an empty entry in my database. Any ideas of a better way to do this? I have also tried saving as a multipart file, but I can't get the ajax post to work with that because it seems to need to be serialized. Any ideas are much appreciated. Thanks!
Here is my controller:
@RequestMapping(value="/directBindAjax", method=RequestMethod.POST)
public @ResponseBody Document docSend(@ModelAttribute(value="document") Document document, Model model) throws IOException {
        FileOutputStream fout = new FileOutputStream(storageService.getUploadDir() + document.getStorage());
        ObjectOutputStream oos = new ObjectOutputStream(fout);
        model.addAttribute("document", document);
        return document;
}Here is my ajax call
$('#attachTheDoc').on('click', function(event){
                var data = $('#newRequiredDocForm').serialize();
                
                $.ajax({
                    type: "POST",
                    url: "/directBindAjax",
                    data: data,
                    processData: false,
                    cache: false,
                    success: function(data, jqXHR){
                       alert("Your files have been saved");
                    }
                });
            });Here is the error I get when I try to do it the way suggested in the other post about sending a form via ajax. I also get a 403 error in my web browser.

Here is my form html:
<form enctype="multipart/form-data" id="newRequiredDocForm"  th:action="@{/directBindAjax}" method="post" th:object="${newDoc}">
  <br/>
  <div class="row">
      <div class="col-xs-4 col-sm-3 text-right"><label class="modalLabel">Type:</label></div>
      <div class="col-xs-8 col-sm-7">
          <select class="form-control" id="type">
              <option value="Invoice">Invoice</option>
              <option value="Binder">Binder</option>
              <option value="Application">Application</option>
          </select>
      </div>
  </div>
  <br/>
  <div class="row">
      <div class="col-xs-4 col-sm-3 text-right">
          <label class="modalLabel">File:</label>
      </div>
      <div class="col-xs-8 col-sm-7">
          <input type="file" id="file" name="upfile" multiple="multiple" style="margin-right:-20px;"/>
      </div>
  </div>
  <br/><br/>
  <div style="text-align: right;">
      <input type="button" id="attachTheDoc" class="btn btn-docModal" value="Upload"/>
  </div>
</form>