Fix #277 -- Embeddable shop (#622)

* Vendor vue.js

* Refactor item_group_by_category to support vouchers

* Widget: Show product list

* Widget: free prices

* Widget: pictures and loading indicator

* Widget: First iframe steps

* Widget: Do not rerender iframe

* Widget: Error handling

* Improve widget

* Widget: localization tech

* Fix invoice style

* Voucher attribute and waiting list

* Add some iframe chrome

* First step to namespaced carts

* More isolation steps

* More cart isolation things

* More cart isolation things

* Mobile stuff

* Show cart on checkout pages

* PayPal and Stripe support

* Enable downloads

* Locale handling

* change text "save URL to this exact page"

* Widget: voucher redemption

* Widget: CSS

* CSS: Responsive

* Widget: CSS improvements

* Widget: Add embedding code generator

* Widget: Error messages and SSL check

* First tests

* Widget: tests

* Don't use IDs in widgets

* Widget: static files caching

src/pretix/base/views/async.py

@@ -51,6 +51,9 @@ class AsyncAction:
             return self.get_result(request)
         return self.http_method_not_allowed(request)
 
+    def _ajax_response_data(self):
+        return {}
+
     def _return_ajax_result(self, res, timeout=.5):
         if not res.ready():
             try:
@@ -59,10 +62,11 @@ class AsyncAction:
                 pass
 
         ready = res.ready()
-        data = {
+        data = self._ajax_response_data()
+        data.update({
             'async_id': res.id,
             'ready': ready
-        }
+        })
         if ready:
             if res.successful() and not isinstance(res.info, Exception):
                 smes = self.get_success_message(res.info)