Allow to pass user data to the widget (#1095)

- [x] Logic
- [x] Tests
- [x] Docs
- [x] find a way to integrate with tracking

doc/spelling_wordlist.txt

@@ -1,5 +1,6 @@
 addon
 addons
+Analytics
 anonymize
 api
 auditability

doc/user/events/widget.rst

@@ -149,8 +149,94 @@ Just as the widget, the button supports the optional attributes ``voucher`` and
 
 You can style the button using the ``pretix-button`` CSS class.
 
-.. versionchanged:: 1.13
+Dynamically loading the widget
+------------------------------
 
-   The pretix Button has been added in version 1.13.
+If you need to control the way or timing the widget loads, for example because you want to modify user data (see
+below) dynamically via JavaScript, you can register a listener that we will call before creating the widget::
+
+    <script type="text/javascript">
+    window.pretixWidgetCallback = function () {
+        // Will be run before we create the widget.
+    }
+    </script>
+
+If you want, you can suppress us loading the widget and/or modify the user data passed to the widget::
+
+    <script type="text/javascript">
+    window.pretixWidgetCallback = function () {
+        window.PretixWidget.build_widgets = false;
+        window.PretixWidget.widget_data["email"] = "test@example.org";
+    }
+    </script>
+
+If you then later want to trigger loading the widgets, just call ``window.PretixWidget.buildWidgets()``.
+
+
+Passing user data to the widget
+-------------------------------
+
+If you display the widget in a restricted area of your website and you want to pre-fill fields in the checkout process
+with known user data to save your users some typing and increase conversions, you can pass additional data attributes
+with that information::
+
+    <pretix-widget event="https://pretix.eu/demo/democon/"
+        data-attendee-name-given-name="John"
+        data-attendee-name-family-name="Doe"
+        data-email="test@example.org"
+        data-question-L9G8NG9M="Foobar">
+    </pretix-widget>
+
+This works for the pretix Button as well. Currently, the following attributes are understood by pretix itself:
+
+* ``data-email`` will pre-fill the order email field as well as the attendee email field (if enabled).
+
+* ``data-question-IDENTIFIER`` will pre-fill the answer for the question with the given identifier. You can view and set
+  identifiers in the *Questions* section of the backend.
+
+* Depending on the person name scheme configured in your event settings, you can pass one or more of
+  ``data-attendee-name-full-name``, ``data-attendee-name-given-name``, ``data-attendee-name-family-name``,
+  ``data-attendee-name-middle-name``, ``data-attendee-name-title``, ``data-attendee-name-calling-name``,
+  ``data-attendee-name-latin-transcription``. If you don't know or don't care, you can also just pass a string as
+  ``data-attendee-name``, which will pre-fill the last part of the name, whatever that is.
+
+Any configured pretix plugins might understand more data fields. For example, if the appropriate plugins on pretix
+Hosted or pretix Enterprise are active, you can pass the following fields:
+
+* If you use the campaigns plugin, you can pass a campaign ID as a value to ``data-campaign``. This way, all orders
+  made through this widget will be counted towards this campaign.
+
+* If you use the tracking plugin, you can pass a Google Analytics User ID to enable cross-domain tracking. This will
+  require you to dynamically load the widget, like this::
+
+    <script>
+        (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
+        (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
+        m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
+        })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
+
+        ga('create', 'UA-XXXXXX-1', 'auto');
+        ga('send', 'pageview');
+
+        window.pretixWidgetCallback = function () {
+            window.PretixWidget.build_widgets = false;
+            window.addEventListener('load', function() { // Wait for GA to be loaded
+                if(window.ga && ga.create) {
+                    ga(function(tracker) {
+                        window.PretixWidget.widget_data["tracking-ga-id"] = tracker.get('clientId');
+                        window.PretixWidget.buildWidgets()
+                    });
+                } else { // Tracking is probably blocked
+                       window.PretixWidget.buildWidgets()
+                }
+            });
+        };
+    </script>
+
+
+.. versionchanged:: 2.3
+
+   Data passing options have been added in pretix 2.3. If you use a self-hosted version of pretix, they only work
+   fully if you configured a redis server.
 
 .. _Let's Encrypt: https://letsencrypt.org/

src/pretix/base/models/items.py

@@ -750,7 +750,7 @@ class Question(LoggedModel):
 
     @staticmethod
     def _clean_identifier(event, code, instance=None):
-        qs = Question.objects.filter(event=event, identifier=code)
+        qs = Question.objects.filter(event=event, identifier__iexact=code)
         if instance:
             qs = qs.exclude(pk=instance.pk)
         if qs.exists():

src/pretix/base/services/cart.py

@@ -4,6 +4,7 @@ from decimal import Decimal
 from typing import List, Optional
 
 from celery.exceptions import MaxRetriesExceededError
+from django.core.exceptions import ValidationError
 from django.db import transaction
 from django.db.models import Q
 from django.dispatch import receiver
@@ -17,9 +18,11 @@ from pretix.base.models import (
 from pretix.base.models.event import SubEvent
 from pretix.base.models.orders import OrderFee
 from pretix.base.models.tax import TAXED_ZERO, TaxedPrice, TaxRule
+from pretix.base.services.checkin import _save_answers
 from pretix.base.services.locking import LockTimeoutException
 from pretix.base.services.pricing import get_price
 from pretix.base.services.tasks import ProfiledTask
+from pretix.base.settings import PERSON_NAME_SCHEMES
 from pretix.base.templatetags.rich_text import rich_text
 from pretix.celery_app import app
 from pretix.presale.signals import (
@@ -99,7 +102,7 @@ class CartManager:
         AddOperation: 30
     }
 
-    def __init__(self, event: Event, cart_id: str, invoice_address: InvoiceAddress=None):
+    def __init__(self, event: Event, cart_id: str, invoice_address: InvoiceAddress=None, widget_data=None):
         self.event = event
         self.cart_id = cart_id
         self.now_dt = now()
@@ -111,6 +114,7 @@ class CartManager:
         self._variations_cache = {}
         self._expiry = None
         self.invoice_address = invoice_address
+        self._widget_data = widget_data or {}
 
     @property
     def positions(self):
@@ -605,12 +609,37 @@ class CartManager:
 
                 if isinstance(op, self.AddOperation):
                     for k in range(available_count):
-                        new_cart_positions.append(CartPosition(
+                        cp = CartPosition(
                             event=self.event, item=op.item, variation=op.variation,
                             price=op.price.gross, expires=self._expiry, cart_id=self.cart_id,
                             voucher=op.voucher, addon_to=op.addon_to if op.addon_to else None,
                             subevent=op.subevent, includes_tax=op.includes_tax
-                        ))
+                        )
+                        if self.event.settings.attendee_names_asked:
+                            scheme = PERSON_NAME_SCHEMES.get(self.event.settings.name_scheme)
+                            if 'attendee-name' in self._widget_data:
+                                cp.attendee_name_parts = {'_legacy': self._widget_data['attendee-name']}
+                            if any('attendee-name-{}'.format(k.replace('_', '-')) in self._widget_data for k, l, w
+                                   in scheme['fields']):
+                                cp.attendee_name_parts = {
+                                    k: self._widget_data.get('attendee-name-{}'.format(k.replace('_', '-')), '')
+                                    for k, l, w in scheme['fields']
+                                }
+                        if self.event.settings.attendee_emails_asked and 'email' in self._widget_data:
+                            cp.attendee_email = self._widget_data.get('email')
+
+                        cp._answers = {}
+                        for k, v in self._widget_data.items():
+                            if not k.startswith('question-'):
+                                continue
+                            q = cp.item.questions.filter(ask_during_checkin=False, identifier__iexact=k[9:]).first()
+                            if q:
+                                try:
+                                    cp._answers[q] = q.clean_answer(v)
+                                except ValidationError:
+                                    pass
+
+                        new_cart_positions.append(cp)
                 elif isinstance(op, self.ExtendOperation):
                     if available_count == 1:
                         op.position.expires = self._expiry
@@ -621,7 +650,11 @@ class CartManager:
                     else:
                         raise AssertionError("ExtendOperation cannot affect more than one item")
 
-        CartPosition.objects.bulk_create(new_cart_positions)
+        for p in new_cart_positions:
+            if p._answers:
+                p.save()
+                _save_answers(p, {}, p._answers)
+        CartPosition.objects.bulk_create([p for p in new_cart_positions if not p._answers])
         return err
 
     def commit(self):
@@ -702,7 +735,7 @@ def get_fees(event, request, total, invoice_address, provider):
 
 @app.task(base=ProfiledTask, bind=True, max_retries=5, default_retry_delay=1, throws=(CartError,))
 def add_items_to_cart(self, event: int, items: List[dict], cart_id: str=None, locale='en',
-                      invoice_address: int=None) -> None:
+                      invoice_address: int=None, widget_data=None) -> None:
     """
     Adds a list of items to a user's cart.
     :param event: The event ID in question
@@ -722,7 +755,7 @@ def add_items_to_cart(self, event: int, items: List[dict], cart_id: str=None, lo
 
         try:
             try:
-                cm = CartManager(event=event, cart_id=cart_id, invoice_address=ia)
+                cm = CartManager(event=event, cart_id=cart_id, invoice_address=ia, widget_data=widget_data)
                 cm.add_new_items(items)
                 cm.commit()
             except LockTimeoutException:

src/pretix/presale/checkoutflow.py

@@ -309,7 +309,10 @@ class QuestionsStep(QuestionsViewMixin, CartMixin, TemplateFlowStep):
     @cached_property
     def contact_form(self):
         initial = {
-            'email': self.cart_session.get('email', '')
+            'email': (
+                self.cart_session.get('email', '') or
+                self.cart_session.get('widget_data', {}).get('email', '')
+            )
         }
         initial.update(self.cart_session.get('contact_form_data', {}))
         return ContactForm(data=self.request.POST if self.request.method == "POST" else None,

src/pretix/presale/templates/pretixpresale/event/voucher.html

@@ -237,6 +237,9 @@
                     <div class="clearfix"></div>
                 </div>
             {% endif %}
+            {% if "widget_data" in request.GET %}
+                <input type="hidden" value="{{ request.GET.widget_data }}" name="widget_data">
+            {% endif %}
         </form>
     {% endif %}
 {% endblock %}

src/pretix/presale/views/cart.py

@@ -1,8 +1,10 @@
+import json
 import mimetypes
 import os
 
 from django.conf import settings
 from django.contrib import messages
+from django.core.cache import caches
 from django.db.models import Q
 from django.http import FileResponse, Http404, JsonResponse
 from django.shortcuts import get_object_or_404, redirect
@@ -33,6 +35,11 @@ from pretix.presale.views.event import (
 )
 from pretix.presale.views.robots import NoSearchIndexViewMixin
 
+try:
+    widget_data_cache = caches['redis']
+except:
+    widget_data_cache = caches['default']
+
 
 class CartActionMixin:
 
@@ -266,11 +273,20 @@ def get_or_create_cart_id(request, create=True):
         cart_data = {}
         if prefix and 'take_cart_id' in request.GET and current_id:
             new_id = current_id
+            cached_widget_data = widget_data_cache.get('widget_data_{}'.format(current_id))
+            if cached_widget_data:
+                cart_data['widget_data'] = cached_widget_data
         else:
             if not create:
                 return None
             new_id = generate_cart_id(request, prefix=prefix)
 
+        if 'widget_data' not in cart_data and 'widget_data' in request.GET:
+            try:
+                cart_data['widget_data'] = json.loads(request.GET.get('widget_data'))
+            except ValueError:
+                pass
+
         if 'carts' not in request.session:
             request.session['carts'] = {}
         if new_id not in request.session['carts']:
@@ -349,10 +365,24 @@ class CartAdd(EventViewMixin, CartActionMixin, AsyncAction, View):
         }
 
     def post(self, request, *args, **kwargs):
+        cart_id = get_or_create_cart_id(self.request)
+        if "widget_data" in request.POST:
+            try:
+                widget_data = json.loads(request.POST.get("widget_data", "{}"))
+            except ValueError:
+                widget_data = {}
+            else:
+                widget_data_cache.set('widget_data_{}'.format(cart_id), widget_data, 600)
+                cs = cart_session(request)
+                cs['widget_data'] = widget_data
+        else:
+            cs = cart_session(request)
+            widget_data = cs.get('widget_data', {})
+
         items = self._items_from_post_data()
         if items:
-            return self.do(self.request.event.id, items, get_or_create_cart_id(self.request), translation.get_language(),
+            return self.do(self.request.event.id, items, cart_id, translation.get_language(),
-                           self.invoice_address.pk)
+                           self.invoice_address.pk, widget_data)
         else:
             if 'ajax' in self.request.GET or 'ajax' in self.request.POST:
                 return JsonResponse({
@@ -449,6 +479,10 @@ class RedeemView(NoSearchIndexViewMixin, EventViewMixin, TemplateView):
     def get(self, request, *args, **kwargs):
         if 'iframe' in request.GET and 'require_cookie' not in request.GET:
             return redirect(request.get_full_path() + '&require_cookie=1')
+
+        if len(self.request.GET.get('widget_data', '{}')) > 3:
+            # We've been passed data from a widget, we need to create a cart session to store it.
+            get_or_create_cart_id(request)
         return super().get(request, *args, **kwargs)
 
 

src/pretix/presale/views/event.py

@@ -189,6 +189,9 @@ class EventIndex(EventViewMixin, CartMixin, TemplateView):
             return redirect(eventreverse(request.event, 'presale:event.index', kwargs=kwargs) + '?require_cookie=true&cart_id={}'.format(
                 request.GET.get('take_cart_id')
             ))
+        elif request.GET.get('iframe', '') == '1' and len(self.request.GET.get('widget_data', '{}')) > 3:
+            # We've been passed data from a widget, we need to create a cart session to store it.
+            get_or_create_cart_id(request)
         elif 'require_cookie' in request.GET and settings.SESSION_COOKIE_NAME not in request.COOKIES:
             # Cookies are in fact not supported
             r = render(request, 'pretixpresale/event/cookies.html', {

src/pretix/static/pretixpresale/js/widget/widget.js

@@ -3,6 +3,11 @@
 /* This is embedded in an isolation wrapper that exposes siteglobals as the global
    scope. */
 
+window.PretixWidget = {
+    'build_widgets': true,
+    'widget_data': {}
+};
+
 var Vue = module.exports;
 
 var strings = {
@@ -457,6 +462,9 @@ var shared_methods = {
             return;
         }
         var redirect_url = this.$root.voucherFormTarget + '&voucher=' + this.voucher + '&subevent=' + this.$root.subevent;
+        if (this.$root.widget_data) {
+            redirect_url += '&widget_data=' + escape(this.$root.widget_data_json);
+        }
         var iframe = this.$root.overlay.$children[0].$refs['frame-container'].children[0];
         this.$root.overlay.frame_loading = true;
         iframe.src = redirect_url;
@@ -466,6 +474,9 @@ var shared_methods = {
         if (this.$root.cart_id) {
             redirect_url += '&take_cart_id=' + this.$root.cart_id;
         }
+        if (this.$root.widget_data) {
+            redirect_url += '&widget_data=' + escape(this.$root.widget_data_json);
+        }
         if (this.$root.useIframe) {
             var iframe = this.$root.overlay.$children[0].$refs['frame-container'].children[0];
             this.$root.overlay.frame_loading = true;
@@ -572,6 +583,7 @@ Vue.component('pretix-widget', {
         + '<form method="post" :action="$root.formTarget" ref="form" target="_blank">'
         + '<input type="hidden" name="_voucher_code" :value="$root.voucher_code" v-if="$root.voucher_code">'
         + '<input type="hidden" name="subevent" :value="$root.subevent" />'
+        + '<input type="hidden" name="widget_data" :value="$root.widget_data_json" />'
         + '<div class="pretix-widget-error-message" v-if="$root.error">{{ $root.error }}</div>'
         + '<div class="pretix-widget-info-message pretix-widget-clickable"'
         + '     v-if="$root.cart_exists">'
@@ -618,6 +630,7 @@ Vue.component('pretix-button', {
         + '<form method="post" :action="$root.formTarget" ref="form" target="_blank">'
         + '<input type="hidden" name="_voucher_code" :value="$root.voucher_code" v-if="$root.voucher_code">'
         + '<input type="hidden" name="subevent" :value="$root.subevent" />'
+        + '<input type="hidden" name="widget_data" :value="$root.widget_data_json" />'
         + '<input type="hidden" v-for="item in $root.items" :name="item.item" :value="item.count" />'
         + '<button class="pretix-button" @click="buy">{{ $root.button_text }}</button>'
         + '</form>'
@@ -733,6 +746,9 @@ var shared_root_computed = {
             }
         }
         return has_priced || cnt_items > 1;
+    },
+    widget_data_json: function () {
+        return JSON.stringify(this.widget_data);
     }
 };
 
@@ -757,6 +773,23 @@ var create_overlay = function (app) {
     app.$root.overlay = framechild;
 };
 
+function get_ga_client_id(tracking_id) {
+    if (typeof ga === "undefined") {
+        return null;
+    }
+    try {
+        var trackers = ga.getAll();
+        var i, len;
+        for (i = 0, len = trackers.length; i < len; i += 1) {
+            if (trackers[i].get('trackingId') === tracking_id) {
+                return trackers[i].get('clientId');
+            }
+        }
+    } catch (e) {
+    }
+    return null;
+}
+
 var create_widget = function (element) {
     var event_url = element.attributes.event.value;
     if (!event_url.match(/\/$/)) {
@@ -766,6 +799,13 @@ var create_widget = function (element) {
     var subevent = element.attributes.subevent ? element.attributes.subevent.value : null;
     var skip_ssl = element.attributes["skip-ssl-check"] ? true : false;
     var disable_vouchers = element.attributes["disable-vouchers"] ? true : false;
+    var widget_data = JSON.parse(JSON.stringify(window.PretixWidget.widget_data));
+    for (var i = 0; i < element.attributes.length; i++) {
+        var attrib = element.attributes[i];
+        if (attrib.name.match(/^data-.*$/)) {
+            widget_data[attrib.name.replace(/^data-/, '')] = attrib.value;
+        }
+    }
 
     if (element.tagName !== "pretix-widget") {
         element.innerHTML = "<pretix-widget></pretix-widget>";
@@ -786,6 +826,7 @@ var create_widget = function (element) {
                 skip_ssl: skip_ssl,
                 error: null,
                 display_add_to_cart: false,
+                widget_data: widget_data,
                 loading: 1,
                 widget_id: 'pretix-widget-' + widget_id,
                 vouchers_exist: false,
@@ -815,6 +856,13 @@ var create_button = function (element) {
     var raw_items = element.attributes.items ? element.attributes.items.value : "";
     var skip_ssl = element.attributes["skip-ssl-check"] ? true : false;
     var button_text = element.innerHTML;
+    var widget_data = JSON.parse(JSON.stringify(window.PretixWidget.widget_data));
+    for (var i = 0; i < element.attributes.length; i++) {
+        var attrib = element.attributes[i];
+        if (attrib.name.match(/^data-.*$/)) {
+            widget_data[attrib.name.replace(/^data-/, '')] = attrib.value;
+        }
+    }
 
     if (element.tagName !== "pretix-button") {
         element.innerHTML = "<pretix-button>" + element.innerHTML + "</pretix-button>";
@@ -840,6 +888,7 @@ var create_button = function (element) {
                 voucher_code: voucher,
                 items: items,
                 error: null,
+                widget_data: widget_data,
                 widget_id: 'pretix-widget-' + widget_id,
                 button_text: button_text
             }
@@ -856,27 +905,35 @@ var create_button = function (element) {
 /* Find all widgets on the page and render them */
 widgetlist = [];
 buttonlist = [];
-document.createElement("pretix-widget");
+window.PretixWidget.buildWidgets = function () {
-document.createElement("pretix-button");
+    document.createElement("pretix-widget");
-docReady(function () {
+    document.createElement("pretix-button");
-    var widgets = document.querySelectorAll("pretix-widget, div.pretix-widget-compat");
+    docReady(function () {
-    var wlength = widgets.length;
+        var widgets = document.querySelectorAll("pretix-widget, div.pretix-widget-compat");
-    for (var i = 0; i < wlength; i++) {
+        var wlength = widgets.length;
-        var widget = widgets[i];
+        for (var i = 0; i < wlength; i++) {
-        widgetlist.push(create_widget(widget));
+            var widget = widgets[i];
-    }
+            widgetlist.push(create_widget(widget));
+        }
 
-    var buttons = document.querySelectorAll("pretix-button, div.pretix-button-compat");
+        var buttons = document.querySelectorAll("pretix-button, div.pretix-button-compat");
-    var blength = buttons.length;
+        var blength = buttons.length;
-    for (var i = 0; i < blength; i++) {
+        for (var i = 0; i < blength; i++) {
-        var button = buttons[i];
+            var button = buttons[i];
-        buttonlist.push(create_button(button));
+            buttonlist.push(create_button(button));
-    }
+        }
-});
+    });
+};
+if (typeof window.pretixWidgetCallback !== "undefined") {
+    window.pretixWidgetCallback();
+}
+if (window.PretixWidget.build_widgets) {
+    window.PretixWidget.buildWidgets();
+}
 
 /* Set a global variable for debugging. In DEBUG mode, siteglobals will be window, otherwise it will be something
    unnamed. */
-siteglobals.pretixwidget = {
+siteglobals.pretixwidget_debug = {
     'Vue': Vue,
     'widgets': widgetlist,
     'buttons': buttonlist

src/tests/presale/test_cart.py

@@ -1,4 +1,5 @@
 import datetime
+import json
 from datetime import timedelta
 from decimal import Decimal
 
@@ -107,6 +108,91 @@ class CartTest(CartTestMixin, TestCase):
         self.assertIsNone(objs[0].variation)
         self.assertEqual(objs[0].price, 23)
 
+    def test_widget_data_post(self):
+        self.event.settings.attendee_names_asked = True
+        self.event.settings.attendee_emails_asked = True
+        q = self.event.questions.create(
+            event=self.event, question='What is your shoe size?', type=Question.TYPE_NUMBER,
+            required=True
+        )
+        q.items.add(self.ticket)
+        response = self.client.post('/%s/%s/cart/add' % (self.orga.slug, self.event.slug), {
+            'item_%d' % self.ticket.id: '1',
+            'widget_data': json.dumps({
+                'attendee-name-full-name': 'John Doe',
+                'email': 'foo@example.com',
+                'question-' + q.identifier: '43'
+            })
+        }, follow=True)
+        self.assertRedirects(response, '/%s/%s/?require_cookie=true' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+        objs = list(CartPosition.objects.filter(cart_id=self.session_key, event=self.event))
+        self.assertEqual(len(objs), 1)
+        self.assertEqual(objs[0].item, self.ticket)
+        self.assertIsNone(objs[0].variation)
+        self.assertEqual(objs[0].price, 23)
+        self.assertEqual(objs[0].attendee_email, "foo@example.com")
+        self.assertEqual(objs[0].attendee_name, "John Doe")
+        a = objs[0].answers.first()
+        self.assertEqual(a.answer, "43")
+        self.assertEqual(a.question, q)
+
+    def test_widget_data_ignored_unknown_or_unasked(self):
+        self.event.settings.attendee_names_asked = False
+        self.event.settings.attendee_emails_asked = False
+        q = self.event.questions.create(
+            event=self.event, question='What is your shoe size?', type=Question.TYPE_NUMBER,
+            required=True
+        )
+        q.items.add(self.ticket)
+        response = self.client.post('/%s/%s/cart/add' % (self.orga.slug, self.event.slug), {
+            'item_%d' % self.ticket.id: '1',
+            'widget_data': json.dumps({
+                'attendee-name-full-name': 'John Doe',
+                'email': 'foo@example.com',
+                'question-' + q.identifier: 'bla'
+            })
+        }, follow=True)
+        self.assertRedirects(response, '/%s/%s/?require_cookie=true' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+        objs = list(CartPosition.objects.filter(cart_id=self.session_key, event=self.event))
+        self.assertEqual(len(objs), 1)
+        self.assertEqual(objs[0].item, self.ticket)
+        self.assertIsNone(objs[0].variation)
+        self.assertEqual(objs[0].price, 23)
+        assert not objs[0].attendee_email
+        assert not objs[0].attendee_name
+        assert not objs[0].answers.exists()
+
+    def test_widget_data_session(self):
+        self.event.settings.attendee_names_asked = True
+        self.event.settings.attendee_emails_asked = True
+        q = self.event.questions.create(
+            event=self.event, question='What is your shoe size?', type=Question.TYPE_NUMBER,
+            required=True
+        )
+        q.items.add(self.ticket)
+        self._set_session('widget_data', {
+            'attendee-name': 'John Doe',
+            'email': 'foo@example.com',
+            'question-' + q.identifier: '43'
+        })
+        response = self.client.post('/%s/%s/cart/add' % (self.orga.slug, self.event.slug), {
+            'item_%d' % self.ticket.id: '1',
+        }, follow=True)
+        self.assertRedirects(response, '/%s/%s/?require_cookie=true' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+        objs = list(CartPosition.objects.filter(cart_id=self.session_key, event=self.event))
+        self.assertEqual(len(objs), 1)
+        self.assertEqual(objs[0].item, self.ticket)
+        self.assertIsNone(objs[0].variation)
+        self.assertEqual(objs[0].price, 23)
+        self.assertEqual(objs[0].attendee_email, "foo@example.com")
+        self.assertEqual(objs[0].attendee_name, "John Doe")
+        a = objs[0].answers.first()
+        self.assertEqual(a.answer, "43")
+        self.assertEqual(a.question, q)
+
     def _set_session(self, key, value):
         session = self.client.session
         session['carts'][get_cart_session_key(self.client, self.event)][key] = value