Shredder: Only force download for tax-relevant data (#1801)

src/pretix/base/services/shredder.py

@@ -75,16 +75,19 @@ def shred(event: Event, fileid: str, confirm_code: str) -> None:
         indexdata = json.loads(zipfile.read('index.json').decode())
     if indexdata['organizer'] != event.organizer.slug or indexdata['event'] != event.slug:
         raise ShredError(_("This file is from a different event."))
-    if indexdata['confirm_code'] != confirm_code:
+    shredders = []
-        raise ShredError(_("The confirm code you entered was incorrect."))
-    if event.logentry_set.filter(datetime__gte=parse(indexdata['time'])):
-        raise ShredError(_("Something happened in your event after the export, please try again."))
-
     for s in indexdata['shredders']:
         shredder = known_shredders.get(s)
         if not shredder:
             continue
+        shredders.append(shredder)
+    if any(shredder.require_download_confirmation for shredder in shredders):
+        if indexdata['confirm_code'] != confirm_code:
+            raise ShredError(_("The confirm code you entered was incorrect."))
+    if event.logentry_set.filter(datetime__gte=parse(indexdata['time'])):
+        raise ShredError(_("Something happened in your event after the export, please try again."))
 
+    for shredder in shredders:
         shredder.shred_data()
 
     cf.file.delete(save=False)

src/pretix/base/shredder.py

@@ -82,6 +82,14 @@ class BaseDataShredder:
         """
         return False
 
+    @property
+    def require_download_confirmation(self):
+        """
+        Indicates whether the data of this shredder needs to be downloaded, before it is actually shredded. By default
+        this value is equal to the tax relevant flag.
+        """
+        return self.tax_relevant
+
     @property
     def verbose_name(self) -> str:
         """

src/pretix/control/templates/pretixcontrol/shredder/download.html

@@ -11,12 +11,16 @@
           method="post" class="form-horizontal" data-asynctask>
         {% csrf_token %}
         <fieldset>
-            <legend>{% trans "Step 1: Download data" %}</legend>
+            {% if download_on_shred %}
+                <legend>{% trans "Step 1: Download data" %}</legend>
+            {% else %}
+                <legend>{% trans "(Optional) Step 1: Download data" %}</legend>
+            {% endif %}
             <p>
                 {% blocktrans trimmed %}
                     You are about to permanently delete data from the server, even though you might be required to
                     keep
-                    some of this data on file. You should therefore download the following file and store it in a safe
+                    some of this data on file. You can therefore download the following file and store it in a safe
                     place:
                 {% endblocktrans %}
             </p>
@@ -27,18 +31,7 @@
             </p>
         </fieldset>
         <fieldset>
-            <legend>{% trans "Step 2: Confirm download" %}</legend>
+            <legend>{% trans "Step 2: Confirm deletion" %}</legend>
-            <p>
-                {% blocktrans trimmed %}
-                    In the downloaded file, there is a text file named "CONFIRM_CODE.txt" with a six-character code.
-                    Please enter this code here to confirm that you successfully downloaded the file.
-                {% endblocktrans %}
-            </p>
-            <input type="text" class="form-control" name="confirm_code" required placeholder="{% trans "Confirmation code" %}">
-            <br>
-        </fieldset>
-        <fieldset>
-            <legend>{% trans "Step 3: Confirm deletion" %}</legend>
             <p>
                 {% blocktrans trimmed with event=request.event.name slug=request.event.slug %}
                 Please re-check that you are fully certain that you want to delete the selected categories of data from the event <strong>{{ event }}</strong>.
@@ -46,7 +39,21 @@
                 {% endblocktrans %}
             </p>
             <input type="text" class="form-control" name="slug" required placeholder="{% trans "Event short name" %}">
+            <br>
         </fieldset>
+        {% if download_on_shred %}
+            <fieldset>
+                <legend>{% trans "Step 3: Confirm download" %}</legend>
+                <p>
+                    {% blocktrans trimmed %}
+                        In the downloaded file, there is a text file named "CONFIRM_CODE.txt" with a six-character code.
+                        Please enter this code here to confirm that you successfully downloaded the file.
+                    {% endblocktrans %}
+                </p>
+                <input type="text" class="form-control" name="confirm_code" required placeholder="{% trans "Confirmation code" %}">
+                <br>
+            </fieldset>
+        {% endif %}
         <input type="hidden" name="file" value="{{ file.pk }}">
         <div class="form-group submit-group">
             <button type="submit" class="btn btn-primary btn-save">

src/pretix/control/views/shredder.py

@@ -1,5 +1,7 @@
+import json
 import logging
 from collections import OrderedDict
+from zipfile import ZipFile
 
 from django.shortcuts import get_object_or_404
 from django.urls import reverse
@@ -43,8 +45,27 @@ class ShredDownloadView(RecentAuthenticationRequiredMixin, EventPermissionRequir
     template_name = 'pretixcontrol/shredder/download.html'
 
     def get_context_data(self, **kwargs):
+        try:
+            cf = CachedFile.objects.get(pk=kwargs['file'])
+        except CachedFile.DoesNotExist:
+            raise ShredError(_("The download file could no longer be found on the server, please try to start again."))
+
+        with ZipFile(cf.file.file, 'r') as zipfile:
+            indexdata = json.loads(zipfile.read('index.json').decode())
+
+        if indexdata['organizer'] != kwargs['organizer'] or indexdata['event'] != kwargs['event']:
+            raise ShredError(_("This file is from a different event."))
+
+        shredders = []
+        for s in indexdata['shredders']:
+            shredder = self.shredders.get(s)
+            if not shredder:
+                continue
+            shredders.append(shredder)
+
         ctx = super().get_context_data(**kwargs)
         ctx['shredders'] = self.shredders
+        ctx['download_on_shred'] = any(shredder.require_download_confirmation for shredder in shredders)
         ctx['file'] = get_object_or_404(CachedFile, pk=kwargs.get("file"))
         return ctx