Replace Item.hidden_if_available with relationship to other Item (#3686)

* draft

* Implementation that is closer to old one

* Fix tests

* Add tests

* Update src/pretix/control/forms/item.py

Co-authored-by: Richard Schreiber <schreiber@rami.io>

* Review notes

---------

Co-authored-by: Richard Schreiber <schreiber@rami.io>

src/pretix/control/forms/item.py

@@ -45,7 +45,7 @@ from django.db.models import Max
 from django.forms.formsets import DELETION_FIELD_NAME
 from django.urls import reverse
 from django.utils.functional import cached_property
-from django.utils.html import escape
+from django.utils.html import escape, format_html
 from django.utils.safestring import mark_safe
 from django.utils.translation import (
     gettext as __, gettext_lazy as _, pgettext_lazy,
@@ -387,6 +387,7 @@ class ItemCreateForm(I18nModelForm):
                 'allow_waitinglist',
                 'show_quota_left',
                 'hidden_if_available',
+                'hidden_if_item_available',
                 'require_bundling',
                 'require_membership',
                 'grant_membership_type',
@@ -550,19 +551,43 @@ class ItemUpdateForm(I18nModelForm):
             widget=forms.CheckboxSelectMultiple
         )
         change_decimal_field(self.fields['default_price'], self.event.currency)
-        self.fields['hidden_if_available'].queryset = self.event.quotas.all()
-        self.fields['hidden_if_available'].widget = Select2(
+
+        if self.instance.hidden_if_available_id:
+            self.fields['hidden_if_available'].queryset = self.event.quotas.all()
+            self.fields['hidden_if_available'].help_text = format_html(
+                "<strong>{}</strong> {}",
+                _("This option is deprecated. For new products, use the newer option below that refers to another "
+                  "product instead of a quota."),
+                self.fields['hidden_if_available'].help_text
+            )
+            self.fields['hidden_if_available'].widget = Select2(
+                attrs={
+                    'data-model-select2': 'generic',
+                    'data-select2-url': reverse('control:event.items.quotas.select2', kwargs={
+                        'event': self.event.slug,
+                        'organizer': self.event.organizer.slug,
+                    }),
+                    'data-placeholder': _('Shown independently of other products')
+                }
+            )
+            self.fields['hidden_if_available'].widget.choices = self.fields['hidden_if_available'].choices
+            self.fields['hidden_if_available'].required = False
+        else:
+            del self.fields['hidden_if_available']
+
+        self.fields['hidden_if_item_available'].queryset = self.event.items.exclude(id=self.instance.id)
+        self.fields['hidden_if_item_available'].widget = Select2(
             attrs={
                 'data-model-select2': 'generic',
-                'data-select2-url': reverse('control:event.items.quotas.select2', kwargs={
+                'data-select2-url': reverse('control:event.items.select2', kwargs={
                     'event': self.event.slug,
                     'organizer': self.event.organizer.slug,
                 }),
                 'data-placeholder': _('Shown independently of other products')
             }
         )
-        self.fields['hidden_if_available'].widget.choices = self.fields['hidden_if_available'].choices
-        self.fields['hidden_if_available'].required = False
+        self.fields['hidden_if_item_available'].widget.choices = self.fields['hidden_if_item_available'].choices
+        self.fields['hidden_if_item_available'].required = False
 
         self.fields['category'].queryset = self.instance.event.categories.all()
         self.fields['category'].widget = Select2(
@@ -683,6 +708,7 @@ class ItemUpdateForm(I18nModelForm):
             'require_bundling',
             'show_quota_left',
             'hidden_if_available',
+            'hidden_if_item_available',
             'issue_giftcard',
             'require_membership',
             'require_membership_types',
@@ -709,6 +735,7 @@ class ItemUpdateForm(I18nModelForm):
             'validity_fixed_from': SplitDateTimeField,
             'validity_fixed_until': SplitDateTimeField,
             'hidden_if_available': SafeModelChoiceField,
+            'hidden_if_item_available': SafeModelChoiceField,
             'grant_membership_type': SafeModelChoiceField,
             'require_membership_types': SafeModelMultipleChoiceField,
         }

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

@@ -32,6 +32,14 @@
             {% endblocktrans %}
         </div>
     {% endif %}
+    {% if not request.event.has_subevents and object.hidden_if_item_available and object.hidden_if_item_available.check_quotas.0 == 100 %}
+        <div class="alert alert-warning">
+            {% blocktrans trimmed %}
+                This product is currently not being shown since you configured below that it should only be visible
+                if a certain other product is already sold out.
+            {% endblocktrans %}
+        </div>
+    {% endif %}
 
     {% block inside %}
     {% endblock %}

src/pretix/control/templates/pretixcontrol/item/index.html

@@ -169,7 +169,10 @@
                         {% endif %}
                         {% bootstrap_field form.allow_cancel layout="control" %}
                         {% bootstrap_field form.allow_waitinglist layout="control" %}
-                        {% bootstrap_field form.hidden_if_available layout="control" %}
+                        {% if form.hidden_if_available %}
+                            {% bootstrap_field form.hidden_if_available layout="control" %}
+                        {% endif %}
+                        {% bootstrap_field form.hidden_if_item_available layout="control" %}
                     </fieldset>
                     {% for v in formsets.values %}
                         <fieldset>