Django Pieces for Autosave Feature

auto_save.coffee

# Debounce to keep too many events from firing
# For notes: http://unscriptable.com/2009/03/20/debouncing-javascript-methods/
debounce = (func, threshold, execAsap) ->
  timeout = null
  (args...) ->
    obj = this
    delayed = ->
      func.apply(obj, args) unless execAsap
      timeout = null
    if timeout
      clearTimeout(timeout)
    else if (execAsap)
      func.apply(obj, args)
    timeout = setTimeout delayed, threshold || 100
		

# Fire the ajax form submit!!!
trigger = debounce((params) ->
  params = {}  unless params?
  $.ajax(
    url: "test.com"
    data: $(".form").serializeArray()
  ).done(->
    alert "Success!  Update if necessary."
    return
  ).fail(->
    alert "Failure!  Notify if necessary."
    return
  ).always ->
    alert "We are done!  Do anything you'll want to happen no matter what."
    return
, 500, true)


# Clicky
$(".form").on "keyup", ->
  trigger()
  
$(".form").on "change", ->
  trigger()

auto_save.js

var debounce = function(func, threshold, execAsap) {
  var timeout = null;
  return function() {
    var args, delayed, obj;
    args = 1 <= arguments.length ? __slice.call(arguments, 0) : [];
    obj = this;
    delayed = function() {
      if (!execAsap) {
        func.apply(obj, args);
      }
      return timeout = null;
    };
    if (timeout) {
      clearTimeout(timeout);
    } else if (execAsap) {
      func.apply(obj, args);
    }
    return timeout = setTimeout(delayed, threshold || 100);
  };
};


var trigger = debounce(function(params) {
  if (params == null) {
    params = {};
  }
  return $.ajax({
    url: "test.com",
    data: $(".form").serializeArray()
  }).done(function() {
    alert("Success!  Update if necessary.");
  }).fail(function() {
    alert("Failure!  Notify if necessary.");
  }).always(function() {
    alert("We are done!  Do anything you'll want to happen no matter what.");
  });
}, 500, true);


$(".form").on("click", function() {
  return trigger();
});

$(".form").on("change", function() {
  return trigger();
});

auto_save.py

class AjaxableResponseMixin(object):
    """
    Mixin to add AJAX support to a form.
    Must be used with an object-based FormView (e.g. CreateView)
    """
    def render_to_json_response(self, context, **response_kwargs):
        data = json.dumps(context)
        response_kwargs['content_type'] = 'application/json'
        return HttpResponse(data, **response_kwargs)

    def form_invalid(self, form):
        response = super(AjaxableResponseMixin, self).form_invalid(form)
        if self.request.is_ajax():
            return self.render_to_json_response(form.errors, status=400)
        else:
            return response

    def form_valid(self, form):
        # We make sure to call the parent's form_valid() method because
        # it might do some processing (in the case of CreateView, it will
        # call form.save() for example).
        response = super(AjaxableResponseMixin, self).form_valid(form)
        if self.request.is_ajax():
            data = {
                'pk': self.object.pk,
            }
            return self.render_to_json_response(data)
        else:
            return response
    
    
# Ajax version
class UserDocumentUpdate(AjaxableResponseMixin, UpdateView):
    model = UserDocument
    context_object_name = 'item'
    fields = ['description', 'document']

    def get_context_data(self, **kwargs):
        context = getattr(super(self.__class__, self), sys._getframe().f_code.co_name)(**kwargs)

        context['address'] = self.object.address
        context['address_form'] = AddressForm(instance=self.object.address)
        return context