Add QR codes for pseudonymization ID

src/pretix/base/migrations/0093_auto_20180528_1432.py

@@ -0,0 +1,45 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.13 on 2018-05-28 14:32
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+from django.utils.crypto import get_random_string
+
+
+def set_pids(apps, schema_editor):
+    OrderPosition = apps.get_model('pretixbase', 'OrderPosition')  # noqa
+    taken = set()
+    charset = list('ABCDEFGHJKLMNPQRSTUVWXYZ3789')
+    for op in OrderPosition.objects.iterator():
+        while True:
+            code = get_random_string(length=10, allowed_chars=charset)
+            if code not in taken:
+                op.pseudonymization_id = code
+                taken.add(code)
+                break
+        op.save(update_fields=['pseudonymization_id'])
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0092_auto_20180511_1224'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='orderposition',
+            name='pseudonymization_id',
+            field=models.CharField(db_index=True, max_length=16, null=True, unique=True),
+        ),
+        migrations.RunPython(
+            set_pids,
+            migrations.RunPython.noop,
+        ),
+        migrations.AlterField(
+            model_name='orderposition',
+            name='pseudonymization_id',
+            field=models.CharField(db_index=True, default='', max_length=16, unique=True),
+            preserve_default=False,
+        ),
+    ]

src/pretix/base/models/orders.py

@@ -835,6 +835,11 @@ class OrderPosition(AbstractPosition):
         verbose_name=_('Tax value')
     )
     secret = models.CharField(max_length=64, default=generate_position_secret, db_index=True)
+    pseudonymization_id = models.CharField(
+        max_length=16,
+        unique=True,
+        db_index=True
+    )
 
     class Meta:
         verbose_name = _("Order position")
@@ -916,8 +921,24 @@ class OrderPosition(AbstractPosition):
         if self.pk is None:
             while OrderPosition.objects.filter(secret=self.secret).exists():
                 self.secret = generate_position_secret()
+
+        if not self.pseudonymization_id:
+            self.assign_pseudonymization_id()
+
         return super().save(*args, **kwargs)
 
+    def assign_pseudonymization_id(self):
+        # This omits some character pairs completely because they are hard to read even on screens (1/I and O/0)
+        # and includes only one of two characters for some pairs because they are sometimes hard to distinguish in
+        # handwriting (2/Z, 4/A, 5/S, 6/G). This allows for better detection e.g. in incoming wire transfers that
+        # might include OCR'd handwritten text
+        charset = list('ABCDEFGHJKLMNPQRSTUVWXYZ3789')
+        while True:
+            code = get_random_string(length=10, allowed_chars=charset)
+            if not OrderPosition.objects.filter(pseudonymization_id=code).exists():
+                self.pseudonymization_id = code
+                return
+
 
 class CartPosition(AbstractPosition):
     """

src/pretix/base/pdf.py

@@ -211,8 +211,14 @@ class Renderer:
                 pdfmetrics.registerFont(TTFont(family + ' B I', finders.find(styles['bolditalic']['truetype'])))
 
     def _draw_barcodearea(self, canvas: Canvas, op: OrderPosition, o: dict):
+        content = o.get('content', 'secret')
+        if content == 'secret':
+            content = op.secret
+        elif content == 'pseudonymization_id':
+            content = op.pseudonymization_id
+
         reqs = float(o['size']) * mm
-        qrw = QrCodeWidget(op.secret, barLevel='H', barHeight=reqs, barWidth=reqs)
+        qrw = QrCodeWidget(content, barLevel='H', barHeight=reqs, barWidth=reqs)
         d = Drawing(reqs, reqs)
         d.add(qrw)
         qr_x = float(o['left']) * mm