Allow dependencies between questions (#1202)

- [x] data model
- [x] api
- [x] backend editor
- [x] backend validation logic
- [x] frontend display logic
- [x] frontend validation logic
- [x] test checkout step
- [x] test modify order in frontend
- [x] test modify order in backend
- [x] validation tests
- [x] correctly evaluate dependency tree in frontend?
- [x] copy events

doc/api/resources/questions.rst

@@ -46,6 +46,16 @@ options                               list of objects            In case of ques
 ├ identifier                          string                     An arbitrary string that can be used for matching with
                                                                  other sources.
 └ answer                              multi-lingual string       The displayed value of this option
+dependency_question                   integer                    Internal ID of a different question. The current
+                                                                 question will only be shown if the question given in
+                                                                 this attribute is set to the value given in
+                                                                 ``dependency_value``. This cannot be combined with
+                                                                 ``ask_during_checkin``.
+dependency_value                      string                     The value ``dependency_question`` needs to be set to.
+                                                                 If ``dependency_question`` is set to a boolean
+                                                                 question, this should be ``"True"`` or ``"False"``.
+                                                                 Otherwise, it should be the ``identifier`` of a
+                                                                 question option.
 ===================================== ========================== =======================================================
 
 .. versionchanged:: 1.12
@@ -100,6 +110,8 @@ Endpoints
             "position": 1,
             "identifier": "WY3TP9SL",
             "ask_during_checkin": false,
+            "dependency_question": null,
+            "dependency_value": null,
             "options": [
               {
                 "id": 1,
@@ -165,6 +177,8 @@ Endpoints
         "position": 1,
         "identifier": "WY3TP9SL",
         "ask_during_checkin": false,
+        "dependency_question": null,
+        "dependency_value": null,
         "options": [
           {
             "id": 1,
@@ -214,6 +228,8 @@ Endpoints
         "items": [1, 2],
         "position": 1,
         "ask_during_checkin": false,
+        "dependency_question": null,
+        "dependency_value": null,
         "options": [
           {
             "answer": {"en": "S"}
@@ -245,6 +261,8 @@ Endpoints
         "position": 1,
         "identifier": "WY3TP9SL",
         "ask_during_checkin": false,
+        "dependency_question": null,
+        "dependency_value": null,
         "options": [
           {
             "id": 1,
@@ -314,6 +332,8 @@ Endpoints
         "position": 2,
         "identifier": "WY3TP9SL",
         "ask_during_checkin": false,
+        "dependency_question": null,
+        "dependency_value": null,
         "options": [
           {
             "id": 1,

src/pretix/api/serializers/item.py

@@ -159,12 +159,20 @@ class QuestionSerializer(I18nAwareModelSerializer):
     class Meta:
         model = Question
         fields = ('id', 'question', 'type', 'required', 'items', 'options', 'position',
-                  'ask_during_checkin', 'identifier')
+                  'ask_during_checkin', 'identifier', 'dependency_question', 'dependency_value')
 
     def validate_identifier(self, value):
         Question._clean_identifier(self.context['event'], value, self.instance)
         return value
 
+    def validate_dependency_question(self, value):
+        if value:
+            if value.type not in (Question.TYPE_CHOICE, Question.TYPE_BOOLEAN, Question.TYPE_CHOICE_MULTIPLE):
+                raise ValidationError('Question dependencies can only be set to boolean or choice questions.')
+        if value == self.instance:
+            raise ValidationError('A question cannot depend on itself.')
+        return value
+
     def validate(self, data):
         data = super().validate(data)
         if self.instance and 'options' in data:
@@ -176,6 +184,18 @@ class QuestionSerializer(I18nAwareModelSerializer):
         full_data = self.to_internal_value(self.to_representation(self.instance)) if self.instance else {}
         full_data.update(data)
 
+        if full_data.get('ask_during_checkin') and full_data.get('dependency_question'):
+            raise ValidationError('Dependencies are not supported during check-in.')
+
+        dep = full_data.get('dependency_question')
+        if dep:
+            seen_ids = {self.instance.pk} if self.instance else set()
+            while dep:
+                if dep.pk in seen_ids:
+                    raise ValidationError(_('Circular dependency between questions detected.'))
+                seen_ids.add(dep.pk)
+                dep = dep.dependency_question
+
         Question.clean_items(event, full_data.get('items'))
         return data
 

src/pretix/base/forms/questions.py

@@ -17,7 +17,7 @@ from pretix.base.forms.widgets import (
     BusinessBooleanRadio, DatePickerWidget, SplitDateTimePickerWidget,
     TimePickerWidget, UploadedFileWidget,
 )
-from pretix.base.models import InvoiceAddress, Question
+from pretix.base.models import InvoiceAddress, Question, QuestionOption
 from pretix.base.models.tax import EU_COUNTRIES
 from pretix.base.settings import PERSON_NAME_SCHEMES
 from pretix.base.templatetags.rich_text import rich_text
@@ -145,6 +145,7 @@ class BaseQuestionsForm(forms.Form):
         item = pos.item
         questions = pos.item.questions_to_ask
         event = kwargs.pop('event')
+        self.all_optional = kwargs.pop('all_optional', False)
 
         super().__init__(*args, **kwargs)
 
@@ -173,6 +174,7 @@ class BaseQuestionsForm(forms.Form):
             tz = pytz.timezone(event.settings.timezone)
             help_text = rich_text(q.help_text)
             label = escape(q.question)  # django-bootstrap3 calls mark_safe
+            required = q.required and not self.all_optional
             if q.type == Question.TYPE_BOOLEAN:
                 if q.required:
                     # For some reason, django-bootstrap3 does not set the required attribute
@@ -187,26 +189,26 @@ class BaseQuestionsForm(forms.Form):
                     initialbool = False
 
                 field = forms.BooleanField(
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
                     initial=initialbool, widget=widget,
                 )
             elif q.type == Question.TYPE_NUMBER:
                 field = forms.DecimalField(
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=q.help_text,
                     initial=initial.answer if initial else None,
                     min_value=Decimal('0.00'),
                 )
             elif q.type == Question.TYPE_STRING:
                 field = forms.CharField(
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
                     initial=initial.answer if initial else None,
                 )
             elif q.type == Question.TYPE_TEXT:
                 field = forms.CharField(
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
                     widget=forms.Textarea,
                     initial=initial.answer if initial else None,
@@ -214,44 +216,46 @@ class BaseQuestionsForm(forms.Form):
             elif q.type == Question.TYPE_CHOICE:
                 field = forms.ModelChoiceField(
                     queryset=q.options,
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
                     widget=forms.Select,
+                    to_field_name='identifier',
                     empty_label='',
                     initial=initial.options.first() if initial else None,
                 )
             elif q.type == Question.TYPE_CHOICE_MULTIPLE:
                 field = forms.ModelMultipleChoiceField(
                     queryset=q.options,
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
+                    to_field_name='identifier',
                     widget=forms.CheckboxSelectMultiple,
                     initial=initial.options.all() if initial else None,
                 )
             elif q.type == Question.TYPE_FILE:
                 field = forms.FileField(
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
                     initial=initial.file if initial else None,
                     widget=UploadedFileWidget(position=pos, event=event, answer=initial),
                 )
             elif q.type == Question.TYPE_DATE:
                 field = forms.DateField(
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
                     initial=dateutil.parser.parse(initial.answer).date() if initial and initial.answer else None,
                     widget=DatePickerWidget(),
                 )
             elif q.type == Question.TYPE_TIME:
                 field = forms.TimeField(
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
                     initial=dateutil.parser.parse(initial.answer).time() if initial and initial.answer else None,
                     widget=TimePickerWidget(time_format=get_format_without_seconds('TIME_INPUT_FORMATS')),
                 )
             elif q.type == Question.TYPE_DATETIME:
                 field = SplitDateTimeField(
-                    label=label, required=q.required,
+                    label=label, required=required,
                     help_text=help_text,
                     initial=dateutil.parser.parse(initial.answer).astimezone(tz) if initial and initial.answer else None,
                     widget=SplitDateTimePickerWidget(time_format=get_format_without_seconds('TIME_INPUT_FORMATS')),
@@ -260,6 +264,15 @@ class BaseQuestionsForm(forms.Form):
             if answers:
                 # Cache the answer object for later use
                 field.answer = answers[0]
+
+            if q.dependency_question_id:
+                field.widget.attrs['data-question-dependency'] = q.dependency_question_id
+                field.widget.attrs['data-question-dependency-value'] = q.dependency_value
+                if q.type != 'M':
+                    field.widget.attrs['required'] = q.required and not self.all_optional
+                    field._required = q.required and not self.all_optional
+                field.required = False
+
             self.fields['question_%s' % q.id] = field
 
         responses = question_form_fields.send(sender=event, position=pos)
@@ -270,6 +283,40 @@ class BaseQuestionsForm(forms.Form):
                 self.fields[key] = value
                 value.initial = data.get('question_form_data', {}).get(key)
 
+    def clean(self):
+        d = super().clean()
+
+        question_cache = {f.question.pk: f.question for f in self.fields.values() if getattr(f, 'question', None)}
+
+        def question_is_visible(parentid, qval):
+            parentq = question_cache[parentid]
+            if parentq.dependency_question_id and not question_is_visible(parentq.dependency_question_id, parentq.dependency_value):
+                return False
+            if 'question_%d' % parentid not in d:
+                return False
+            dval = d.get('question_%d' % parentid)
+            if qval == 'True':
+                return dval
+            elif qval == 'False':
+                return not dval
+            elif isinstance(dval, QuestionOption):
+                return dval.identifier == qval
+            else:
+                return qval in [o.identifier for o in dval]
+
+        def question_is_required(q):
+            return (
+                q.required and
+                (not q.dependency_question_id or question_is_visible(q.dependency_question_id, q.dependency_value))
+            )
+
+        if not self.all_optional:
+            for q in question_cache.values():
+                if question_is_required(q) and not d.get('question_%d' % q.pk):
+                    raise ValidationError({'question_%d' % q.pk: [_('This field is required')]})
+
+        return d
+
 
 class BaseInvoiceAddressForm(forms.ModelForm):
     vat_warning = False

src/pretix/base/migrations/0113_auto_20190312_0942.py

@@ -0,0 +1,27 @@
+# Generated by Django 2.1.5 on 2019-03-12 09:42
+
+import django.db.models.deletion
+import jsonfallback.fields
+from django.db import migrations, models
+
+import pretix.base.models.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0112_auto_20190304_1726'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='question',
+            name='dependency_question',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='dependent_questions', to='pretixbase.Question'),
+        ),
+        migrations.AddField(
+            model_name='question',
+            name='dependency_value',
+            field=models.TextField(blank=True, null=True),
+        ),
+    ]

src/pretix/base/models/event.py

@@ -515,6 +515,10 @@ class Event(EventMixin, LoggedModel):
                 o.question = q
                 o.save()
 
+        for q in self.questions.filter(dependency_question__isnull=False):
+            q.dependency_question = question_map[q.dependency_question_id]
+            q.save(update_fields=['dependency_question'])
+
         for cl in other.checkin_lists.filter(subevent__isnull=True).prefetch_related('limit_products'):
             items = list(cl.limit_products.all())
             cl.pk = None

src/pretix/base/models/items.py

@@ -702,6 +702,10 @@ class Question(LoggedModel):
     :type ask_during_checkin: bool
     :param identifier: An arbitrary, internal identifier
     :type identifier: str
+    :param dependency_question: This question will only show up if the referenced question is set to `dependency_value`.
+    :type dependency_question: Question
+    :param dependency_value: The value that `dependency_question` needs to be set to for this question to be applicable.
+    :type dependency_value: str
     """
     TYPE_NUMBER = "N"
     TYPE_STRING = "S"
@@ -771,6 +775,10 @@ class Question(LoggedModel):
                     'pretixdesk 0.2 or newer.'),
         default=False
     )
+    dependency_question = models.ForeignKey(
+        'Question', null=True, blank=True, on_delete=models.SET_NULL, related_name='dependent_questions'
+    )
+    dependency_value = models.TextField(null=True, blank=True)
 
     class Meta:
         verbose_name = _("Question")

src/pretix/base/views/mixins.py

@@ -17,6 +17,7 @@ from pretix.base.models import (
 
 class BaseQuestionsViewMixin:
     form_class = BaseQuestionsForm
+    all_optional = False
 
     @staticmethod
     def _keyfunc(pos):
@@ -47,6 +48,7 @@ class BaseQuestionsViewMixin:
                                    prefix=cr.id,
                                    cartpos=cartpos,
                                    orderpos=orderpos,
+                                   all_optional=self.all_optional,
                                    data=(self.request.POST if self.request.method == 'POST' else None),
                                    files=(self.request.FILES if self.request.method == 'POST' else None))
             form.pos = cartpos or orderpos
@@ -154,7 +156,7 @@ class OrderQuestionsViewMixin(BaseQuestionsViewMixin):
 
     @cached_property
     def positions(self):
-        qqs = Question.objects.all()
+        qqs = self.request.event.questions.all()
         if self.only_user_visible:
             qqs = qqs.filter(ask_during_checkin=False)
         return list(self.order.positions.select_related(
@@ -173,7 +175,7 @@ class OrderQuestionsViewMixin(BaseQuestionsViewMixin):
                              Question.objects.none(),
                              to_attr='dummy'
                          )))
-                     ),
+                     ).select_related('dependency_question'),
                      to_attr='questions_to_ask')
         ))
 

src/pretix/control/forms/item.py

@@ -36,14 +36,39 @@ class CategoryForm(I18nModelForm):
 class QuestionForm(I18nModelForm):
     question = I18nFormField(
         label=_("Question"),
-        widget_kwargs={'attrs': {'rows': 5}},
+        widget_kwargs={'attrs': {'rows': 2}},
         widget=I18nTextarea
     )
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.fields['items'].queryset = self.instance.event.items.all()
+        self.fields['dependency_question'].queryset = self.instance.event.questions.filter(
+            type__in=(Question.TYPE_BOOLEAN, Question.TYPE_CHOICE, Question.TYPE_CHOICE_MULTIPLE)
+        )
+        if self.instance.pk:
+            self.fields['dependency_question'].queryset = self.fields['dependency_question'].queryset.exclude(
+                pk=self.instance.pk
+            )
         self.fields['identifier'].required = False
+        self.fields['help_text'].widget.attrs['rows'] = 3
+
+    def clean_dependency_question(self):
+        dep = val = self.cleaned_data.get('dependency_question')
+        if dep:
+            seen_ids = {self.instance.pk} if self.instance else set()
+            while dep:
+                if dep.pk in seen_ids:
+                    raise ValidationError(_('Circular dependency between questions detected.'))
+                seen_ids.add(dep.pk)
+                dep = dep.dependency_question
+        return val
+
+    def clean(self):
+        d = super().clean()
+        if d.get('dependency_question') and not d.get('dependency_value'):
+            raise ValidationError({'dependency_value': [_('This field is required')]})
+        return d
 
     class Meta:
         model = Question
@@ -55,12 +80,15 @@ class QuestionForm(I18nModelForm):
             'required',
             'ask_during_checkin',
             'identifier',
-            'items'
+            'items',
+            'dependency_question',
+            'dependency_value'
         ]
         widgets = {
             'items': forms.CheckboxSelectMultiple(
                 attrs={'class': 'scrolling-multiple-choice'}
             ),
+            'dependency_value': forms.Select,
         }
 
 

src/pretix/control/templates/pretixcontrol/base.html

@@ -33,6 +33,7 @@
             <script type="text/javascript" src="{% static "charts/morris.js" %}"></script>
             <script type="text/javascript" src="{% static "clipboard/clipboard.js" %}"></script>
             <script type="text/javascript" src="{% static "rrule/rrule.js" %}"></script>
+            <script type="text/javascript" src="{% static "pretixpresale/js/ui/questions.js" %}"></script>
             <script type="text/javascript" src="{% static "pretixcontrol/js/jquery.qrcode.min.js" %}"></script>
             <script type="text/javascript" src="{% static "pretixcontrol/js/clipboard.js" %}"></script>
             <script type="text/javascript" src="{% static "pretixcontrol/js/menu.js" %}"></script>
@@ -70,7 +71,10 @@
 	</head>
 	<body data-datetimeformat="{{ js_datetime_format }}" data-timeformat="{{ js_time_format }}"
             data-dateformat="{{ js_date_format }}" data-datetimelocale="{{ js_locale }}"
+            data-pretixlocale="{{ request.LANGUAGE_CODE }}"
             data-payment-weekdays-disabled="{{ js_payment_weekdays_disabled }}"
+            {% if request.organizer %}data-organizer="{{ request.organizer.slug }}"{% endif %}
+            {% if request.event %}data-event="{{ request.event.slug }}"{% endif %}
             data-select2-locale="{{ select2locale }}" data-longdateformat="{{ js_long_date_format }}" class="nojs">
         <div id="wrapper">
             <nav class="navbar navbar-inverse navbar-static-top" role="navigation">

src/pretix/control/templates/pretixcontrol/items/question_edit.html

@@ -21,15 +21,9 @@
         <fieldset>
             <legend>{% trans "General information" %}</legend>
             {% bootstrap_field form.question layout="control" %}
-            {% bootstrap_field form.help_text layout="control" %}
             {% bootstrap_field form.type layout="control" %}
-            {% bootstrap_field form.identifier layout="control" %}
-            {% bootstrap_field form.ask_during_checkin layout="control" %}
-            {% bootstrap_field form.required layout="control" %}
-        </fieldset>
-        <fieldset>
-            <legend>{% trans "Apply to products" %}</legend>
             {% bootstrap_field form.items layout="control" %}
+            {% bootstrap_field form.required layout="control" %}
         </fieldset>
         <div class="alert alert-info alert-required-boolean">
             {% blocktrans trimmed %}
@@ -110,6 +104,26 @@
                 </p>
             </div>
         </fieldset>
+        <fieldset>
+            <legend>{% trans "Advanced settings" %}</legend>
+            {% bootstrap_field form.help_text layout="control" %}
+            {% bootstrap_field form.identifier layout="control" %}
+            {% bootstrap_field form.ask_during_checkin layout="control" %}
+
+            <div class="form-group">
+                <label class="col-md-3 control-label" for="id_dependency_question">
+                    {% trans "Question dependency" %}
+                    <br><span class="optional">{% trans "Optional" context "form" %}</span>
+                </label>
+                <div class="col-md-4">
+                    {% bootstrap_field form.dependency_question layout="inline" form_group_class="inner" %}
+                </div>
+                <div class="col-md-5">
+                    <script type="text/plain" id="dependency_value_val">{{ form.instance.dependency_value }}</script>
+                    {% bootstrap_field form.dependency_value layout="inline" form_group_class="inner" %}
+                </div>
+            </div>
+        </fieldset>
         <div class="form-group submit-group">
             <button type="submit" class="btn btn-primary btn-save">
                 {% trans "Save" %}

src/pretix/presale/checkoutflow.py

@@ -414,10 +414,34 @@ class QuestionsStep(QuestionsViewMixin, CartMixin, TemplateFlowStep):
 
         for cp in self._positions_for_questions:
             answ = {
-                aw.question_id: aw.answer for aw in cp.answerlist
+                aw.question_id: aw for aw in cp.answerlist
             }
+            question_cache = {
+                q.pk: q for q in cp.item.questions_to_ask
+            }
+
+            def question_is_visible(parentid, qval):
+                parentq = question_cache[parentid]
+                if parentq.dependency_question_id and not question_is_visible(parentq.dependency_question_id, parentq.dependency_value):
+                    return False
+                if parentid not in answ:
+                    return False
+                if qval == 'True':
+                    return answ[parentid].answer == 'True'
+                elif qval == 'False':
+                    return answ[parentid].answer == 'False'
+                else:
+                    return qval in [o.identifier for o in answ[parentid].options.all()]
+
+            def question_is_required(q):
+                return (
+                    q.required and
+                    (not q.dependency_question_id or question_is_visible(q.dependency_question_id, q.dependency_value))
+                )
+
             for q in cp.item.questions_to_ask:
-                if q.required and q.id not in answ:
+                print("question", q, "is required", question_is_required(q), "has answer", q.id in answ)
+                if question_is_required(q) and not answ.get(q.id):
                     if warn:
                         messages.warning(request, _('Please fill in answers to all required questions.'))
                     return False

src/pretix/presale/templates/pretixpresale/base.html

@@ -26,6 +26,7 @@
         <script type="text/javascript" src="{% static "bootstrap/js/bootstrap.js" %}"></script>
         <script type="text/javascript" src="{% static "datetimepicker/bootstrap-datetimepicker.js" %}"></script>
         <script type="text/javascript" src="{% static "pretixcontrol/js/jquery.qrcode.min.js" %}"></script>
+        <script type="text/javascript" src="{% static "pretixpresale/js/ui/questions.js" %}"></script>
         <script type="text/javascript" src="{% static "pretixpresale/js/ui/main.js" %}"></script>
         <script type="text/javascript" src="{% static "pretixbase/js/asynctask.js" %}"></script>
         <script type="text/javascript" src="{% static "pretixbase/js/details.js" %}"></script>

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

@@ -65,7 +65,7 @@
                         </h4>
                     </summary>
                     <div>
-                        <div class="panel-body" data-idx="{{ forloop.counter0 }}">
+                        <div class="panel-body questions-form" data-idx="{{ forloop.counter0 }}">
                             {% if pos.addons.all %}
                                 <div class="form-group">
                                     <label class="col-md-3 control-label">
@@ -97,7 +97,7 @@
                                     {# Add-Ons #}
                                     <legend>+ {{ form.pos.item }}</legend>
                                 {% endif %}
-                                {% bootstrap_form form layout="horizontal" %}
+                                {% bootstrap_form form layout="checkout" %}
                             {% endfor %}
                         </div>
                     </div>

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

@@ -53,13 +53,13 @@
                         </h4>
                     </summary>
                     <div id="cp{{ pos.id }}">
-                        <div class="panel-body">
+                        <div class="panel-body questions-form">
                             {% for form in forms %}
                                 {% if form.pos.item != pos.item %}
                                     {# Add-Ons #}
                                     <legend>+ {{ form.pos.item }}</legend>
                                 {% endif %}
-                                {% bootstrap_form form layout="horizontal" %}
+                                {% bootstrap_form form layout="checkout" %}
                             {% endfor %}
                         </div>
                     </div>

src/pretix/presale/views/questions.py

@@ -13,7 +13,7 @@ class QuestionsViewMixin(BaseQuestionsViewMixin):
 
     @cached_property
     def _positions_for_questions(self):
-        qqs = Question.objects.all()
+        qqs = self.request.event.questions.all()
         if self.only_user_visible:
             qqs = qqs.filter(ask_during_checkin=False)
         cart = get_cart(self.request).select_related(
@@ -33,7 +33,7 @@ class QuestionsViewMixin(BaseQuestionsViewMixin):
                              Question.objects.none(),
                              to_attr='dummy'
                          )))
-                     ),
+                     ).select_related('dependency_question'),
                      to_attr='questions_to_ask')
         )
         return sorted(list(cart), key=self._keyfunc)

src/pretix/static/pretixcontrol/js/ui/main.js

@@ -1,13 +1,5 @@
 /*global $,gettext*/
 
-function question_page_toggle_view() {
-    var show = $("#id_type").val() == "C" || $("#id_type").val() == "M";
-    $("#answer-options").toggle(show);
-
-    show = $("#id_type").val() == "B" && $("#id_required").prop("checked");
-    $(".alert-required-boolean").toggle(show);
-}
-
 var waitingDialog = {
     show: function (message) {
         "use strict";
@@ -34,6 +26,26 @@ var ajaxErrDialog = {
     }
 };
 
+var apiGET = function (url, callback) {
+    $.getJSON(url, function (data) {
+        callback(data);
+    });
+};
+
+var i18nToString = function (i18nstring) {
+    var locale = $("body").attr("data-pretixlocale");
+    if (i18nstring[locale]) {
+        return i18nstring[locale];
+    } else if (i18nstring["en"]) {
+        return i18nstring["en"];
+    }
+    for (key in i18nstring) {
+        if (i18nstring[key]) {
+            return i18nstring[key];
+        }
+    }
+};
+
 $(document).ajaxError(function (event, jqXHR, settings, thrownError) {
     waitingDialog.hide();
     var c = $(jqXHR.responseText).filter('.container');
@@ -423,6 +435,9 @@ var form_handlers = function (el) {
             }
         );
     });
+
+    el.find("input[name*=question], select[name*=question]").change(questions_toggle_dependent);
+    questions_toggle_dependent();
 };
 
 $(function () {
@@ -491,14 +506,6 @@ $(function () {
         window.location.hash = e.target.hash;
     });
 
-    // Question editor
-    if ($("#answer-options").length) {
-
-        $("#id_type").change(question_page_toggle_view);
-        $("#id_required").change(question_page_toggle_view);
-        question_page_toggle_view();
-    }
-
     // Event wizard
     $("#event-slug-random-generate").click(function () {
         var url = $(this).attr("data-rng-url");

src/pretix/static/pretixcontrol/js/ui/question.js

@@ -1,5 +1,6 @@
 /*global $, Morris, gettext*/
 $(function () {
+    // Question view
     if (!$("#question-stats").length) {
         return;
     }
@@ -73,3 +74,66 @@ $(function () {
 
     // N, S, T
 });
+
+$(function () {
+    // Question editor
+
+    if (!$("#answer-options").length) {
+        return;
+    }
+
+    // Question editor
+    $("#id_type").change(question_page_toggle_view);
+    $("#id_required").change(question_page_toggle_view);
+    question_page_toggle_view();
+
+    function question_page_toggle_view() {
+        var show = $("#id_type").val() == "C" || $("#id_type").val() == "M";
+        $("#answer-options").toggle(show);
+
+        show = $("#id_type").val() == "B" && $("#id_required").prop("checked");
+        $(".alert-required-boolean").toggle(show);
+    }
+
+    var $val = $("#id_dependency_value");
+    var $dq = $("#id_dependency_question");
+    var oldval = $("#dependency_value_val").text();
+    function update_dependency_options() {
+        $val.parent().find(".loading-indicator").remove();
+        $("#id_dependency_value option").remove();
+        $("#id_dependency_value").prop("required", false);
+
+        var val = $dq.children("option:selected").val();
+        if (!val) {
+            $("#id_dependency_value").show();
+            $val.show();
+            return;
+        }
+
+        $("#id_dependency_value").prop("required", true);
+        $val.hide();
+        $val.parent().append("<div class=\"help-block loading-indicator\"><span class=\"fa" +
+            " fa-cog fa-spin\"></span></div>");
+
+        apiGET('/api/v1/organizers/' + $("body").attr("data-organizer") + '/events/' + $("body").attr("data-event") + '/questions/' + val + '/', function (data) {
+            if (data.type === "B") {
+                $val.append($("<option>").attr("value", "True").text(gettext("Ja")));
+                $val.append($("<option>").attr("value", "False").text(gettext("Nein")));
+            } else {
+                for (var i = 0; i < data.options.length; i++) {
+                    var opt = data.options[i];
+                    var $opt = $("<option>").attr("value", opt.identifier).text(i18nToString(opt.answer));
+                    $val.append($opt);
+                }
+            }
+            if (oldval) {
+                $val.val(oldval);
+            }
+            $val.parent().find(".loading-indicator").remove();
+            $val.show();
+        });
+    }
+
+    update_dependency_options();
+    $dq.change(update_dependency_options);
+});

src/pretix/static/pretixpresale/js/ui/main.js

@@ -6,6 +6,7 @@ function gettext(msgid) {
     }
     return msgid;
 }
+
 function ngettext(singular, plural, count) {
     if (typeof django !== 'undefined' && typeof django.ngettext !== 'undefined') {
         return django.ngettext(singular, plural, count);
@@ -14,7 +15,7 @@ function ngettext(singular, plural, count) {
 }
 
 var form_handlers = function (el) {
-    el.find(".datetimepicker").each(function() {
+    el.find(".datetimepicker").each(function () {
         $(this).datetimepicker({
             format: $("body").attr("data-datetimeformat"),
             locale: $("body").attr("data-datetimelocale"),
@@ -37,7 +38,7 @@ var form_handlers = function (el) {
         }
     });
 
-    el.find(".datepickerfield").each(function() {
+    el.find(".datepickerfield").each(function () {
         var opts = {
             format: $("body").attr("data-dateformat"),
             locale: $("body").attr("data-datetimelocale"),
@@ -71,7 +72,7 @@ var form_handlers = function (el) {
         }
     });
 
-    el.find(".timepickerfield").each(function() {
+    el.find(".timepickerfield").each(function () {
         var opts = {
             format: $("body").attr("data-timeformat"),
             locale: $("body").attr("data-datetimelocale"),
@@ -90,7 +91,7 @@ var form_handlers = function (el) {
             }
         };
         $(this).datetimepicker(opts);
-	});
+    });
 
     el.find("script[data-replace-with-qr]").each(function () {
         var $div = $("<div>");
@@ -104,7 +105,10 @@ var form_handlers = function (el) {
             }
         );
     });
-}
+
+    el.find("input[name*=question], select[name*=question]").change(questions_toggle_dependent);
+    questions_toggle_dependent();
+};
 
 
 $(function () {
@@ -130,7 +134,7 @@ $(function () {
         $("#voucher-box").slideDown();
         $("#voucher-toggle").slideUp();
     });
-    
+
     $('[data-toggle="tooltip"]').tooltip();
 
     $("#ajaxerr").on("click", ".ajaxerr-close", ajaxErrDialog.hide);
@@ -140,7 +144,7 @@ $(function () {
     $('.toggle-variation-description').click(function () {
         $(this).parent().find('.addon-variation-description').slideToggle();
     });
-    
+
     // Copy answers
     $(".js-copy-answers").click(function (e) {
         e.preventDefault();
@@ -153,7 +157,7 @@ $(function () {
     // Subevent choice
     if ($(".subevent-toggle").length) {
         $(".subevent-list").hide();
-        $(".subevent-toggle").css("display", "block").click(function() {
+        $(".subevent-toggle").css("display", "block").click(function () {
             $(".subevent-list").slideToggle(300);
         });
     }
@@ -165,7 +169,7 @@ $(function () {
     var update_cart_form = function () {
         var is_enabled = $(".product-row input[type=checkbox]:checked, .variations input[type=checkbox]:checked, .product-row input[type=radio]:checked, .variations input[type=radio]:checked").length;
         if (!is_enabled) {
-            $(".input-item-count").each(function() {
+            $(".input-item-count").each(function () {
                 if ($(this).val() && $(this).val() !== "0") {
                     is_enabled = true;
                 }
@@ -185,18 +189,18 @@ $(function () {
 
     // Invoice address form
     $("input[data-required-if]").each(function () {
-      var dependent = $(this),
-        dependency = $($(this).attr("data-required-if")),
-        update = function (ev) {
-          var enabled = (dependency.attr("type") === 'checkbox' || dependency.attr("type") === 'radio') ? dependency.prop('checked') : !!dependency.val();
-          if (!dependent.is("[data-no-required-attr]")) {
-              dependent.prop('required', enabled);
-          }
-          dependent.closest('.form-group').toggleClass('required', enabled);
-        };
-      update();
-      dependency.closest('.form-group').find('input[name=' + dependency.attr("name") + ']').on("change", update);
-      dependency.closest('.form-group').find('input[name=' + dependency.attr("name") + ']').on("dp.change", update);
+        var dependent = $(this),
+            dependency = $($(this).attr("data-required-if")),
+            update = function (ev) {
+                var enabled = (dependency.attr("type") === 'checkbox' || dependency.attr("type") === 'radio') ? dependency.prop('checked') : !!dependency.val();
+                if (!dependent.is("[data-no-required-attr]")) {
+                    dependent.prop('required', enabled);
+                }
+                dependent.closest('.form-group').toggleClass('required', enabled);
+            };
+        update();
+        dependency.closest('.form-group').find('input[name=' + dependency.attr("name") + ']').on("change", update);
+        dependency.closest('.form-group').find('input[name=' + dependency.attr("name") + ']').on("dp.change", update);
     });
 
     $("input[data-display-dependency]").each(function () {
@@ -219,16 +223,16 @@ $(function () {
         dependency.closest('.form-group').find('input[name=' + dependency.attr("name") + ']').on("dp.change", update);
     });
 
-	form_handlers($("body"));
+    form_handlers($("body"));
 
     // Lightbox
     lightbox.init();
 });
 
-function copy_answers(idx) {    
-    var elements = $('*[data-idx="'+idx+'"] input, *[data-idx="'+idx+'"] select, *[data-idx="'+idx+'"] textarea');
+function copy_answers(idx) {
+    var elements = $('*[data-idx="' + idx + '"] input, *[data-idx="' + idx + '"] select, *[data-idx="' + idx + '"] textarea');
     var firstAnswers = $('*[data-idx="0"] input, *[data-idx="0"] select, *[data-idx="0"] textarea');
-    elements.each(function(index){
+    elements.each(function (index) {
         var input = $(this),
             tagName = input.prop('tagName').toLowerCase(),
             attributeType = input.attr('type'),
@@ -250,14 +254,20 @@ function copy_answers(idx) {
                         break;
                     case "checkbox":
                     case "radio":
-                        input.prop("checked", firstAnswers.filter("[name$=" + suffix + "]").prop("checked"));
+                        if (input.attr('value')) {
+                            input.prop("checked", firstAnswers.filter("[name$=" + suffix + "][value=" + input.attr('value') + "]").prop("checked"));
+                        } else {
+                            input.prop("checked", firstAnswers.filter("[name$=" + suffix + "]").prop("checked"));
+                        }
                         break;
                     default:
                         input.val(firstAnswers.filter("[name$=" + suffix + "]").val());
-                } 
+                }
                 break;
             default:
                 input.val(firstAnswers.filter("[name$=" + suffix + "]").val());
-        } 
+        }
     });
+    questions_toggle_dependent(true);
 }
+

src/pretix/static/pretixpresale/js/ui/questions.js

@@ -0,0 +1,71 @@
+/*global $ */
+
+function questions_toggle_dependent(ev) {
+    function q_should_be_shown($el) {
+        if (!$el.attr('data-question-dependency')) {
+            return true;
+        }
+
+        var dependency_name = $el.attr("name").split("_")[0] + "_" + $el.attr("data-question-dependency");
+        var dependency_value = $el.attr("data-question-dependency-value");
+        var $dependency_el;
+
+        if ($("select[name=" + dependency_name + "]").length) {
+            // dependency is type C
+            $dependency_el = $("select[name=" + dependency_name + "]");
+            if (!$dependency_el.closest(".form-group").hasClass("dependency-hidden")) {  // do not show things that depend on hidden things
+                return q_should_be_shown($dependency_el) && $dependency_el.val() === dependency_value;
+            }
+        } else if ($("input[type=checkbox][name=" + dependency_name + "]").length) {
+            // dependency type is B or M
+            if (dependency_value === "True" || dependency_value === "False") {
+                $dependency_el = $("input[name=" + dependency_name + "]");
+                if (!$dependency_el.closest(".form-group").hasClass("dependency-hidden")) {  // do not show things that depend on hidden things
+                    if (dependency_value === "True") {
+                        return q_should_be_shown($dependency_el) && $dependency_el.prop('checked');
+                    } else {
+                        return q_should_be_shown($dependency_el) && !$dependency_el.prop('checked');
+                    }
+                }
+            } else {
+                $dependency_el = $("input[value=" + dependency_value + "][name=" + dependency_name + "]");
+                if (!$dependency_el.closest(".form-group").hasClass("dependency-hidden")) {  // do not show things that depend on hidden things
+                    return q_should_be_shown($dependency_el) && $dependency_el.prop('checked');
+                }
+            }
+        }
+    }
+
+    $("[data-question-dependency]").each(function () {
+        var $dependent = $(this).closest(".form-group");
+        var is_shown = !$dependent.hasClass("dependency-hidden");
+        var should_be_shown = q_should_be_shown($(this));
+
+        if (should_be_shown && !is_shown) {
+            $dependent.stop().removeClass("dependency-hidden");
+            if (!ev) {
+                $dependent.show();
+            } else {
+                $dependent.slideDown();
+            }
+            $dependent.find("input.required-hidden, select.required-hidden, textarea.required-hidden").each(function () {
+                $(this).prop("required", true).removeClass("required-hidden");
+            });
+        } else if (!should_be_shown && is_shown) {
+            if ($dependent.hasClass("has-error") || $dependent.find(".has-error").length) {
+                // Do not hide things with invalid validation
+                return;
+            }
+            $dependent.stop().addClass("dependency-hidden");
+            if (!ev) {
+                $dependent.hide();
+            } else {
+                $dependent.slideUp();
+            }
+            $dependent.find("input[required], select[required], textarea[required]").each(function () {
+                $(this).prop("required", false).addClass("required-hidden");
+            });
+        }
+
+    });
+}

src/tests/api/test_items.py

@@ -1302,6 +1302,8 @@ TEST_QUESTION_RES = {
     "ask_during_checkin": False,
     "identifier": "ABC",
     "position": 0,
+    "dependency_question": None,
+    "dependency_value": None,
     "options": [
         {
             "id": 0,
@@ -1418,6 +1420,65 @@ def test_question_create(token_client, organizer, event, event2, item):
     assert resp.status_code == 400
     assert resp.content.decode() == '{"identifier":["This identifier is already used for a different question."]}'
 
+    resp = token_client.post(
+        '/api/v1/organizers/{}/events/{}/questions/'.format(organizer.slug, event.slug),
+        {
+            "question": "What's your name?",
+            "type": "S",
+            "required": True,
+            "items": [item.pk],
+            "position": 0,
+            "ask_during_checkin": False,
+            "dependency_question": question.pk,
+            "dependency_value": "1",
+            "identifier": None
+        },
+        format='json'
+    )
+    assert resp.status_code == 400
+    assert resp.content.decode() == '{"dependency_question":["Question dependencies can only be set to boolean or choice questions."]}'
+
+    question.type = Question.TYPE_BOOLEAN
+    question.save()
+    resp = token_client.post(
+        '/api/v1/organizers/{}/events/{}/questions/'.format(organizer.slug, event.slug),
+        {
+            "question": "What's your name?",
+            "type": "S",
+            "required": True,
+            "items": [item.pk],
+            "position": 0,
+            "ask_during_checkin": True,
+            "dependency_question": question.pk,
+            "dependency_value": "1",
+            "identifier": None
+        },
+        format='json'
+    )
+    assert resp.status_code == 400
+    assert resp.content.decode() == '{"non_field_errors":["Dependencies are not supported during check-in."]}'
+
+    question.type = Question.TYPE_BOOLEAN
+    question.save()
+    resp = token_client.post(
+        '/api/v1/organizers/{}/events/{}/questions/'.format(organizer.slug, event.slug),
+        {
+            "question": "What's your name?",
+            "type": "S",
+            "required": True,
+            "items": [item.pk],
+            "position": 0,
+            "ask_during_checkin": False,
+            "dependency_question": question.pk,
+            "dependency_value": "1",
+            "identifier": None
+        },
+        format='json'
+    )
+    assert resp.status_code == 201
+    q2 = Question.objects.get(pk=resp.data['id'])
+    assert q2.dependency_question == question
+
 
 @pytest.mark.django_db
 def test_question_update(token_client, organizer, event, question):
@@ -1429,13 +1490,26 @@ def test_question_update(token_client, organizer, event, question):
         },
         format='json'
     )
-    print(resp.content)
     assert resp.status_code == 200
     question = Question.objects.get(pk=resp.data['id'])
     assert question.question == "What's your shoe size?"
     assert question.type == "N"
 
 
+@pytest.mark.django_db
+def test_question_update_circular_dependency(token_client, organizer, event, question):
+    q2 = event.questions.create(question="T-Shirt size", type="B", identifier="FOO", dependency_question=question)
+    resp = token_client.patch(
+        '/api/v1/organizers/{}/events/{}/questions/{}/'.format(organizer.slug, event.slug, question.pk),
+        {
+            "dependency_question": q2.pk
+        },
+        format='json'
+    )
+    assert resp.status_code == 400
+    assert resp.content.decode() == '{"non_field_errors":["Circular dependency between questions detected."]}'
+
+
 @pytest.mark.django_db
 def test_question_update_options(token_client, organizer, event, question, item):
     resp = token_client.patch(

src/tests/control/test_items.py

@@ -212,6 +212,45 @@ class QuestionsTest(ItemFormTest):
         tbl = doc.select('.container-fluid table.table-bordered tbody')[0]
         assert tbl.select('tr')[0].select('td')[0].text.strip() == '42'
 
+    def test_set_dependency(self):
+        q1 = Question.objects.create(event=self.event1, question="What country are you from?", type="C", required=True)
+        q2 = Question.objects.create(event=self.event1, question="What city are you from?", type="T", required=True)
+        o1 = q1.options.create(answer='Germany')
+        doc = self.get_doc('/control/event/%s/%s/questions/%s/change' % (self.orga1.slug, self.event1.slug, q2.id))
+        form_data = extract_form_fields(doc.select('.container-fluid form')[0])
+        form_data['dependency_question'] = q1.pk
+        form_data['dependency_value'] = o1.identifier
+        doc = self.post_doc('/control/event/%s/%s/questions/%s/change' % (self.orga1.slug, self.event1.slug, q2.id),
+                            form_data)
+        assert doc.select(".alert-success")
+        q2.refresh_from_db()
+        assert q2.dependency_question == q1
+        assert q2.dependency_value == o1.identifier
+
+    def test_set_dependency_circular(self):
+        q1 = Question.objects.create(event=self.event1, question="What country are you from?", type="C", required=True)
+        o1 = q1.options.create(answer='Germany')
+        q2 = Question.objects.create(event=self.event1, question="What city are you from?", type="C", required=True,
+                                     dependency_question=q1, dependency_value=o1.identifier)
+        doc = self.get_doc('/control/event/%s/%s/questions/%s/change' % (self.orga1.slug, self.event1.slug, q1.id))
+        form_data = extract_form_fields(doc.select('.container-fluid form')[0])
+        form_data['dependency_question'] = q2.pk
+        form_data['dependency_value'] = '1'
+        doc = self.post_doc('/control/event/%s/%s/questions/%s/change' % (self.orga1.slug, self.event1.slug, q1.id),
+                            form_data)
+        assert not doc.select(".alert-success")
+
+    def test_set_dependency_to_non_choice(self):
+        q1 = Question.objects.create(event=self.event1, question="What country are you from?", type="N", required=True)
+        q2 = Question.objects.create(event=self.event1, question="What city are you from?", type="T", required=True)
+        doc = self.get_doc('/control/event/%s/%s/questions/%s/change' % (self.orga1.slug, self.event1.slug, q2.id))
+        form_data = extract_form_fields(doc.select('.container-fluid form')[0])
+        form_data['dependency_question'] = q1.pk
+        form_data['dependency_value'] = '1'
+        doc = self.post_doc('/control/event/%s/%s/questions/%s/change' % (self.orga1.slug, self.event1.slug, q2.id),
+                            form_data)
+        assert not doc.select(".alert-success")
+
 
 class QuotaTest(ItemFormTest):
 

src/tests/presale/test_checkout.py

@@ -22,7 +22,7 @@ from pretix.base.models.items import ItemAddOn, ItemVariation, SubEventItem
 from pretix.testutils.sessions import get_cart_session_key
 
 
-class CheckoutTestCase(TestCase):
+class BaseCheckoutTestCase:
     def setUp(self):
         super().setUp()
         self.orga = Organizer.objects.create(name='CCC', slug='ccc')
@@ -60,6 +60,14 @@ class CheckoutTestCase(TestCase):
         self.workshopquota.variations.add(self.workshop2a)
         self.workshopquota.variations.add(self.workshop2b)
 
+    def _set_session(self, key, value):
+        session = self.client.session
+        session['carts'][get_cart_session_key(self.client, self.event)][key] = value
+        session.save()
+
+
+class CheckoutTestCase(BaseCheckoutTestCase, TestCase):
+
     def _enable_reverse_charge(self):
         self.tr19.eu_reverse_charge = True
         self.tr19.home_country = Country('DE')
@@ -76,135 +84,6 @@ class CheckoutTestCase(TestCase):
         self.assertRedirects(response, '/%s/%s/?require_cookie=true' % (self.orga.slug, self.event.slug),
                              target_status_code=200)
 
-    def test_timezone(self):
-        """ Test basic timezone change handling by date and time questions """
-        q1 = Question.objects.create(
-            event=self.event, question='When did you wake up today?', type=Question.TYPE_TIME,
-            required=True
-        )
-        q2 = Question.objects.create(
-            event=self.event, question='When was your last haircut?', type=Question.TYPE_DATE,
-            required=True
-        )
-        q3 = Question.objects.create(
-            event=self.event, question='When are you going to arrive?', type=Question.TYPE_DATETIME,
-            required=True
-        )
-        self.ticket.questions.add(q1)
-        self.ticket.questions.add(q2)
-        self.ticket.questions.add(q3)
-        cr = CartPosition.objects.create(
-            event=self.event, cart_id=self.session_key, item=self.ticket,
-            price=23, expires=now() + timedelta(minutes=10)
-        )
-        response = self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), {
-            '%s-question_%s' % (cr.id, q1.id): '06:30',
-            '%s-question_%s' % (cr.id, q2.id): '2005-12-31',
-            '%s-question_%s_0' % (cr.id, q3.id): '2018-01-01',
-            '%s-question_%s_1' % (cr.id, q3.id): '5:23',
-            'email': 'admin@localhost',
-        }, follow=True)
-        self.assertRedirects(response, '/%s/%s/checkout/payment/' % (self.orga.slug, self.event.slug), target_status_code=200)
-        self.event.settings.set('timezone', 'US/Central')
-        o1 = QuestionAnswer.objects.get(question=q1)
-        o2 = QuestionAnswer.objects.get(question=q2)
-        o3 = QuestionAnswer.objects.get(question=q3)
-        order = Order.objects.create(event=self.event, status=Order.STATUS_PAID,
-                                     expires=now() + timedelta(days=3),
-                                     total=4)
-        op = OrderPosition.objects.create(order=order, item=self.ticket, price=42)
-        o1.cartposition, o2.cartposition, o3.cartposition = None, None, None
-        o1.orderposition, o2.orderposition, o3.orderposition = op, op, op
-        # only time and date answers should be unaffected by timezone change
-        self.assertEqual(str(o1), '06:30')
-        self.assertEqual(str(o2), '2005-12-31')
-        o3date, o3time = str(o3).split(' ')
-        self.assertEqual(o3date, '2017-12-31')
-        self.assertEqual(o3time, '23:23')
-
-    def test_addon_questions(self):
-        q1 = Question.objects.create(
-            event=self.event, question='Age', type=Question.TYPE_NUMBER,
-            required=True
-        )
-        q1.items.add(self.ticket)
-        q1.items.add(self.workshop1)
-        ItemAddOn.objects.create(base_item=self.ticket, addon_category=self.workshopcat, min_count=1,
-                                 price_included=True)
-        cp1 = CartPosition.objects.create(
-            event=self.event, cart_id=self.session_key, item=self.ticket,
-            price=23, expires=now() + timedelta(minutes=10)
-        )
-        cp1.answers.create(question=q1, answer='12')
-        cp2 = CartPosition.objects.create(
-            event=self.event, cart_id=self.session_key, item=self.workshop1, addon_to=cp1,
-            price=0, expires=now() + timedelta(minutes=10)
-        )
-        cp2.answers.create(question=q1, answer='12')
-
-        self._set_session('payment', 'banktransfer')
-        response = self.client.post('/%s/%s/checkout/confirm/' % (self.orga.slug, self.event.slug), follow=True)
-        doc = BeautifulSoup(response.rendered_content, "lxml")
-        self.assertEqual(len(doc.select(".thank-you")), 1)
-        self.assertEqual(OrderPosition.objects.filter(item=self.ticket).first().answers.first().answer, '12')
-        self.assertEqual(OrderPosition.objects.filter(item=self.workshop1).first().answers.first().answer, '12')
-
-    def test_questions(self):
-        q1 = Question.objects.create(
-            event=self.event, question='Age', type=Question.TYPE_NUMBER,
-            required=True
-        )
-        q2 = Question.objects.create(
-            event=self.event, question='How have you heard from us?', type=Question.TYPE_STRING,
-            required=False
-        )
-        self.ticket.questions.add(q1)
-        self.ticket.questions.add(q2)
-        cr1 = CartPosition.objects.create(
-            event=self.event, cart_id=self.session_key, item=self.ticket,
-            price=23, expires=now() + timedelta(minutes=10)
-        )
-        cr2 = CartPosition.objects.create(
-            event=self.event, cart_id=self.session_key, item=self.ticket,
-            price=20, expires=now() + timedelta(minutes=10)
-        )
-        response = self.client.get('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), follow=True)
-        doc = BeautifulSoup(response.rendered_content, "lxml")
-
-        self.assertEqual(len(doc.select('input[name="%s-question_%s"]' % (cr1.id, q1.id))), 1)
-        self.assertEqual(len(doc.select('input[name="%s-question_%s"]' % (cr2.id, q1.id))), 1)
-        self.assertEqual(len(doc.select('input[name="%s-question_%s"]' % (cr1.id, q2.id))), 1)
-        self.assertEqual(len(doc.select('input[name="%s-question_%s"]' % (cr2.id, q2.id))), 1)
-
-        # Not all required fields filled out, expect failure
-        response = self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), {
-            '%s-question_%s' % (cr1.id, q1.id): '42',
-            '%s-question_%s' % (cr2.id, q1.id): '',
-            '%s-question_%s' % (cr1.id, q2.id): 'Internet',
-            '%s-question_%s' % (cr2.id, q2.id): '',
-            'email': 'admin@localhost'
-        }, follow=True)
-        doc = BeautifulSoup(response.rendered_content, "lxml")
-        self.assertGreaterEqual(len(doc.select('.has-error')), 1)
-
-        # Corrected request
-        response = self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), {
-            '%s-question_%s' % (cr1.id, q1.id): '42',
-            '%s-question_%s' % (cr2.id, q1.id): '23',
-            '%s-question_%s' % (cr1.id, q2.id): 'Internet',
-            '%s-question_%s' % (cr2.id, q2.id): '',
-            'email': 'admin@localhost'
-        }, follow=True)
-        self.assertRedirects(response, '/%s/%s/checkout/payment/' % (self.orga.slug, self.event.slug),
-                             target_status_code=200)
-
-        cr1 = CartPosition.objects.get(id=cr1.id)
-        cr2 = CartPosition.objects.get(id=cr2.id)
-        self.assertEqual(cr1.answers.filter(question=q1).count(), 1)
-        self.assertEqual(cr2.answers.filter(question=q1).count(), 1)
-        self.assertEqual(cr1.answers.filter(question=q2).count(), 1)
-        self.assertFalse(cr2.answers.filter(question=q2).exists())
-
     def test_reverse_charge(self):
         self.tr19.eu_reverse_charge = True
         self.tr19.home_country = Country('DE')
@@ -900,11 +779,6 @@ class CheckoutTestCase(TestCase):
         self.assertRedirects(response, '/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug),
                              target_status_code=200)
 
-    def _set_session(self, key, value):
-        session = self.client.session
-        session['carts'][get_cart_session_key(self.client, self.event)][key] = value
-        session.save()
-
     def test_subevent(self):
         self.event.has_subevents = True
         self.event.save()
@@ -1831,3 +1705,279 @@ class CheckoutTestCase(TestCase):
         self.assertEqual(len(doc.select(".thank-you")), 1)
         assert not Order.objects.last().testmode
         assert "0" not in Order.objects.last().code
+
+
+class QuestionsTestCase(BaseCheckoutTestCase, TestCase):
+
+    def test_timezone(self):
+        """ Test basic timezone change handling by date and time questions """
+        q1 = Question.objects.create(
+            event=self.event, question='When did you wake up today?', type=Question.TYPE_TIME,
+            required=True
+        )
+        q2 = Question.objects.create(
+            event=self.event, question='When was your last haircut?', type=Question.TYPE_DATE,
+            required=True
+        )
+        q3 = Question.objects.create(
+            event=self.event, question='When are you going to arrive?', type=Question.TYPE_DATETIME,
+            required=True
+        )
+        self.ticket.questions.add(q1)
+        self.ticket.questions.add(q2)
+        self.ticket.questions.add(q3)
+        cr = CartPosition.objects.create(
+            event=self.event, cart_id=self.session_key, item=self.ticket,
+            price=23, expires=now() + timedelta(minutes=10)
+        )
+        response = self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), {
+            '%s-question_%s' % (cr.id, q1.id): '06:30',
+            '%s-question_%s' % (cr.id, q2.id): '2005-12-31',
+            '%s-question_%s_0' % (cr.id, q3.id): '2018-01-01',
+            '%s-question_%s_1' % (cr.id, q3.id): '5:23',
+            'email': 'admin@localhost',
+        }, follow=True)
+        self.assertRedirects(response, '/%s/%s/checkout/payment/' % (self.orga.slug, self.event.slug), target_status_code=200)
+        self.event.settings.set('timezone', 'US/Central')
+        o1 = QuestionAnswer.objects.get(question=q1)
+        o2 = QuestionAnswer.objects.get(question=q2)
+        o3 = QuestionAnswer.objects.get(question=q3)
+        order = Order.objects.create(event=self.event, status=Order.STATUS_PAID,
+                                     expires=now() + timedelta(days=3),
+                                     total=4)
+        op = OrderPosition.objects.create(order=order, item=self.ticket, price=42)
+        o1.cartposition, o2.cartposition, o3.cartposition = None, None, None
+        o1.orderposition, o2.orderposition, o3.orderposition = op, op, op
+        # only time and date answers should be unaffected by timezone change
+        self.assertEqual(str(o1), '06:30')
+        self.assertEqual(str(o2), '2005-12-31')
+        o3date, o3time = str(o3).split(' ')
+        self.assertEqual(o3date, '2017-12-31')
+        self.assertEqual(o3time, '23:23')
+
+    def test_addon_questions(self):
+        q1 = Question.objects.create(
+            event=self.event, question='Age', type=Question.TYPE_NUMBER,
+            required=True
+        )
+        q1.items.add(self.ticket)
+        q1.items.add(self.workshop1)
+        ItemAddOn.objects.create(base_item=self.ticket, addon_category=self.workshopcat, min_count=1,
+                                 price_included=True)
+        cp1 = CartPosition.objects.create(
+            event=self.event, cart_id=self.session_key, item=self.ticket,
+            price=23, expires=now() + timedelta(minutes=10)
+        )
+        cp1.answers.create(question=q1, answer='12')
+        cp2 = CartPosition.objects.create(
+            event=self.event, cart_id=self.session_key, item=self.workshop1, addon_to=cp1,
+            price=0, expires=now() + timedelta(minutes=10)
+        )
+        cp2.answers.create(question=q1, answer='12')
+
+        self._set_session('payment', 'banktransfer')
+        response = self.client.post('/%s/%s/checkout/confirm/' % (self.orga.slug, self.event.slug), follow=True)
+        doc = BeautifulSoup(response.rendered_content, "lxml")
+        self.assertEqual(len(doc.select(".thank-you")), 1)
+        self.assertEqual(OrderPosition.objects.filter(item=self.ticket).first().answers.first().answer, '12')
+        self.assertEqual(OrderPosition.objects.filter(item=self.workshop1).first().answers.first().answer, '12')
+
+    def test_questions(self):
+        q1 = Question.objects.create(
+            event=self.event, question='Age', type=Question.TYPE_NUMBER,
+            required=True
+        )
+        q2 = Question.objects.create(
+            event=self.event, question='How have you heard from us?', type=Question.TYPE_STRING,
+            required=False
+        )
+        self.ticket.questions.add(q1)
+        self.ticket.questions.add(q2)
+        cr1 = CartPosition.objects.create(
+            event=self.event, cart_id=self.session_key, item=self.ticket,
+            price=23, expires=now() + timedelta(minutes=10)
+        )
+        cr2 = CartPosition.objects.create(
+            event=self.event, cart_id=self.session_key, item=self.ticket,
+            price=20, expires=now() + timedelta(minutes=10)
+        )
+        response = self.client.get('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), follow=True)
+        doc = BeautifulSoup(response.rendered_content, "lxml")
+
+        self.assertEqual(len(doc.select('input[name="%s-question_%s"]' % (cr1.id, q1.id))), 1)
+        self.assertEqual(len(doc.select('input[name="%s-question_%s"]' % (cr2.id, q1.id))), 1)
+        self.assertEqual(len(doc.select('input[name="%s-question_%s"]' % (cr1.id, q2.id))), 1)
+        self.assertEqual(len(doc.select('input[name="%s-question_%s"]' % (cr2.id, q2.id))), 1)
+
+        # Not all required fields filled out, expect failure
+        response = self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), {
+            '%s-question_%s' % (cr1.id, q1.id): '42',
+            '%s-question_%s' % (cr2.id, q1.id): '',
+            '%s-question_%s' % (cr1.id, q2.id): 'Internet',
+            '%s-question_%s' % (cr2.id, q2.id): '',
+            'email': 'admin@localhost'
+        }, follow=True)
+        doc = BeautifulSoup(response.rendered_content, "lxml")
+        self.assertGreaterEqual(len(doc.select('.has-error')), 1)
+
+        # Corrected request
+        response = self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), {
+            '%s-question_%s' % (cr1.id, q1.id): '42',
+            '%s-question_%s' % (cr2.id, q1.id): '23',
+            '%s-question_%s' % (cr1.id, q2.id): 'Internet',
+            '%s-question_%s' % (cr2.id, q2.id): '',
+            'email': 'admin@localhost'
+        }, follow=True)
+        self.assertRedirects(response, '/%s/%s/checkout/payment/' % (self.orga.slug, self.event.slug),
+                             target_status_code=200)
+
+        cr1 = CartPosition.objects.get(id=cr1.id)
+        cr2 = CartPosition.objects.get(id=cr2.id)
+        self.assertEqual(cr1.answers.filter(question=q1).count(), 1)
+        self.assertEqual(cr2.answers.filter(question=q1).count(), 1)
+        self.assertEqual(cr1.answers.filter(question=q2).count(), 1)
+        self.assertFalse(cr2.answers.filter(question=q2).exists())
+
+    def _test_question_input(self, data, should_fail):
+        cr1 = CartPosition.objects.create(
+            event=self.event, cart_id=self.session_key, item=self.ticket,
+            price=23, expires=now() + timedelta(minutes=10)
+        )
+        pl = {
+            ('%s-question_%s' % (cr1.id, k.id)): v for k, v in data.items() if v != 'False'
+        }
+        pl['email'] = 'admin@localhost'
+        response = self.client.post('/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug), pl, follow=True)
+        if should_fail:
+            doc = BeautifulSoup(response.rendered_content, "lxml")
+            assert doc.select('.has-error')
+            assert doc.select('.alert-danger')
+        else:
+            self.assertRedirects(response, '/%s/%s/checkout/payment/' % (self.orga.slug, self.event.slug),
+                                 target_status_code=200)
+            cr1.answers.all().delete()
+
+        for k, v in data.items():
+            a = cr1.answers.create(question=k, answer=str(v))
+            if k.type in ('M', 'C'):
+                a.options.add(*k.options.filter(identifier__in=(v if isinstance(v, list) else [v])))
+
+        response = self.client.get('/%s/%s/checkout/payment/' % (self.orga.slug, self.event.slug), follow=True)
+        if should_fail:
+            self.assertRedirects(response, '/%s/%s/checkout/questions/' % (self.orga.slug, self.event.slug),
+                                 target_status_code=200)
+            doc = BeautifulSoup(response.rendered_content, "lxml")
+            assert doc.select('.alert-warning')
+        else:
+            assert response.status_code == 200
+            doc = BeautifulSoup(response.rendered_content, "lxml")
+            assert not doc.select('.alert-warning')
+
+    def _setup_dependency_questions(self):
+        self.q1 = self.event.questions.create(
+            event=self.event, question='What industry are you in?', type=Question.TYPE_CHOICE,
+            required=True
+        )
+        self.q1.options.create(answer='Tech', identifier='TECH')
+        self.q1.options.create(answer='Health', identifier='HEALTH')
+
+        self.q2a = self.event.questions.create(
+            event=self.event, question='What is your occupation?', type=Question.TYPE_CHOICE_MULTIPLE,
+            required=False, dependency_question=self.q1, dependency_value='TECH'
+        )
+        self.q2a.options.create(answer='Software developer', identifier='DEV')
+        self.q2a.options.create(answer='System administrator', identifier='ADMIN')
+
+        self.q2b = self.event.questions.create(
+            event=self.event, question='What is your occupation?', type=Question.TYPE_CHOICE_MULTIPLE,
+            required=True, dependency_question=self.q1, dependency_value='HEALTH'
+        )
+        self.q2b.options.create(answer='Doctor', identifier='DOC')
+        self.q2b.options.create(answer='Nurse', identifier='NURSE')
+
+        self.q3 = self.event.questions.create(
+            event=self.event, question='Do you like Python?', type=Question.TYPE_BOOLEAN,
+            required=False, dependency_question=self.q2a, dependency_value='DEV'
+        )
+        self.q4a = self.event.questions.create(
+            event=self.event, question='Why?', type=Question.TYPE_TEXT,
+            required=True, dependency_question=self.q3, dependency_value='True'
+        )
+        self.q4b = self.event.questions.create(
+            event=self.event, question='Why not?', type=Question.TYPE_TEXT,
+            required=True, dependency_question=self.q3, dependency_value='False'
+        )
+        self.ticket.questions.add(self.q1)
+        self.ticket.questions.add(self.q2a)
+        self.ticket.questions.add(self.q2b)
+        self.ticket.questions.add(self.q3)
+        self.ticket.questions.add(self.q4a)
+        self.ticket.questions.add(self.q4b)
+
+    def test_question_dependencies_first_path(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'HEALTH',
+            self.q2b: 'NURSE'
+        }, should_fail=False)
+
+    def test_question_dependencies_sidepath_ignored(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'HEALTH',
+            self.q2b: 'NURSE',
+            self.q2a: 'DEV',
+            self.q3: 'True',
+        }, should_fail=False)
+
+    def test_question_dependencies_first_path_required(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'HEALTH',
+        }, should_fail=True)
+
+    def test_question_dependencies_second_path(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'TECH',
+            self.q2a: 'DEV',
+            self.q3: 'True',
+            self.q4a: 'No curly braces!'
+        }, should_fail=False)
+
+    def test_question_dependencies_subitem_required(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'HEALTH',
+        }, should_fail=True)
+
+    def test_question_dependencies_subsubitem_required(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'TECH',
+            self.q2a: 'DEV',
+            self.q3: 'True',
+        }, should_fail=True)
+
+    def test_question_dependencies_parent_not_required(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'TECH',
+        }, should_fail=False)
+
+    def test_question_dependencies_conditional_require_bool(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'TECH',
+            self.q2a: 'DEV',
+            self.q3: 'False',
+            self.q4b: 'No curly braces!'
+        }, should_fail=False)
+
+    def test_question_dependencies_conditional_require_bool_fail(self):
+        self._setup_dependency_questions()
+        self._test_question_input({
+            self.q1: 'TECH',
+            self.q2a: 'DEV',
+            self.q3: 'False',
+        }, should_fail=True)