Allow to adjust the order of products (closes #60)

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

@@ -3,6 +3,13 @@
 {% block title %}{% trans "Products" %}{% endblock %}
 {% block inside %}
 	<h1>{% trans "Products" %}</h1>
+    <p>
+        {% blocktrans trimmed %}
+            Below, you find a list of all available products. You can click on a product name to inspect and change
+            product details. You can also use the buttons on the right to change the order of products within a
+            give category.
+        {% endblocktrans %}
+    </p>
     <p>
         <a href="{% url "control:event.items.add" organizer=request.event.organizer.slug event=request.event.slug %}"
                 class="btn btn-default"><i class="fa fa-plus"></i> {% trans "Create new product" %}</a>
@@ -12,16 +19,24 @@
 			<tr>
 				<th>{% trans "Product name" %}</th>
 				<th>{% trans "Category" %}</th>
+                <th></th>
 			</tr>
 		</thead>
 		<tbody>
-			{% for i in items %}
-			<tr>
-				<td><strong><a href="
-				{% url "control:event.item" organizer=request.event.organizer.slug event=request.event.slug item=i.identity %}">{{ i.name }}</a></strong></td>
-				<td>{% if i.category %}{{ i.category.name }}{% endif %}</td>
-			</tr>
-			{% endfor %}
+            {% regroup items by category as cat_list %}
+            {% for c in cat_list %}
+                {% for i in c.list %}
+                <tr>
+                    <td><strong><a href="
+                    {% url "control:event.item" organizer=request.event.organizer.slug event=request.event.slug item=i.identity %}">{{ i.name }}</a></strong></td>
+                    <td>{% if i.category %}{{ i.category.name }}{% endif %}</td>
+                    <td>
+                        <a href="{% url "control:event.items.up" organizer=request.event.organizer.slug event=request.event.slug item=i.identity %}" class="btn btn-default btn-sm {% if forloop.counter0 == 0 %}disabled{% endif %}"><i class="fa fa-arrow-up"></i></a>
+                        <a href="{% url "control:event.items.down" organizer=request.event.organizer.slug event=request.event.slug item=i.identity %}" class="btn btn-default btn-sm {% if forloop.revcounter0 == 0 %}disabled{% endif %}"><i class="fa fa-arrow-down"></i></a>
+                    </td>
+                </tr>
+                {% endfor %}
+            {% endfor %}
 		</tbody>
 	</table>
     {% include "pretixcontrol/pagination.html" %}

src/pretix/control/urls.py

@@ -27,6 +27,8 @@ urlpatterns = [
             name='event.item.variations'),
         url(r'^items/(?P<item>[0-9a-f-]+)/restrictions$', item.ItemRestrictions.as_view(),
             name='event.item.restrictions'),
+        url(r'^items/(?P<item>[0-9a-f-]+)/up$', item.item_move_up, name='event.items.up'),
+        url(r'^items/(?P<item>[0-9a-f-]+)/down$', item.item_move_down, name='event.items.down'),
         url(r'^categories/$', item.CategoryList.as_view(), name='event.items.categories'),
         url(r'^categories/(?P<category>[0-9a-f-]+)/delete$', item.CategoryDelete.as_view(),
             name='event.items.categories.delete'),

src/pretix/control/views/item.py

@@ -27,7 +27,9 @@ from . import UpdateView, CreateView
 class ItemList(ListView):
     model = Item
     context_object_name = 'items'
-    paginate_by = 30
+    # paginate_by = 30
+    # Pagination is disabled as it is very unlikely to be necessary
+    # here and could cause problems with the "reorder-within-category" feature
     template_name = 'pretixcontrol/items/index.html'
 
     def get_queryset(self):
@@ -36,6 +38,49 @@ class ItemList(ListView):
         ).prefetch_related("category")
 
 
+def item_move(request, item, up=True):
+    """
+    This is a helper function to avoid duplicating code in item_move_up and
+    item_move_down. It takes an item and a direction and then tries to bring
+    all items for this category in a new order.
+    """
+    try:
+        item = request.event.items.current.get(
+            identity=item
+        )
+    except Item.DoesNotExist:
+        raise Http404(_("The requested product does not exist."))
+    items = list(request.event.items.current.filter(category=item.category).order_by("position"))
+
+    index = items.index(item)
+    if index != 0 and up:
+        items[index - 1], items[index] = items[index], items[index - 1]
+    elif index != len(items) - 1 and not up:
+        items[index + 1], items[index] = items[index], items[index + 1]
+
+    for i, item in enumerate(items):
+        if item.position != i:
+            item.position = i
+            item.save()  # TODO: Clone or document sloppiness?
+    messages.success(request, _('The order of items as been updated.'))
+
+
+@event_permission_required("can_change_items")
+def item_move_up(request, organizer, event, item):
+    item_move(request, item, up=True)
+    return redirect('control:event.items',
+                    organizer=request.event.organizer.slug,
+                    event=request.event.slug)
+
+
+@event_permission_required("can_change_items")
+def item_move_down(request, organizer, event, item):
+    item_move(request, item, up=False)
+    return redirect('control:event.items',
+                    organizer=request.event.organizer.slug,
+                    event=request.event.slug)
+
+
 class CategoryForm(VersionedModelForm):
 
     class Meta:
@@ -159,6 +204,7 @@ def category_move(request, category, up=True):
         if cat.position != i:
             cat.position = i
             cat.save()  # TODO: Clone or document sloppiness?
+    messages.success(request, _('The order of categories as been updated.'))
 
 
 @event_permission_required("can_change_items")