Add field internal_reference to invoice addresses

src/pretix/base/invoice.py

@@ -331,6 +331,12 @@ class ClassicInvoiceRenderer(BaseReportlabInvoiceRenderer):
             NextPageTemplate('OtherPages'),
         ]
 
+        if self.invoice.internal_reference:
+            story.append(Paragraph(
+                pgettext('invoice', 'Your reference: {reference}').format(reference=self.invoice.internal_reference),
+                self.stylesheet['Normal']
+            ))
+
         if self.invoice.introductory_text:
             story.append(Paragraph(self.invoice.introductory_text, self.stylesheet['Normal']))
             story.append(Spacer(1, 10 * mm))

src/pretix/base/migrations/0082_invoiceaddress_internal_reference.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.2 on 2017-10-26 22:13
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0081_quota_cached_availability_paid_orders'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='invoiceaddress',
+            name='internal_reference',
+            field=models.TextField(blank=True, help_text='This reference will be printed on your invoice for your convenience.', verbose_name='Internal reference'),
+        ),
+        migrations.AddField(
+            model_name='invoice',
+            name='internal_reference',
+            field=models.TextField(blank=True),
+        ),
+    ]

src/pretix/base/models/invoices.py

@@ -81,6 +81,7 @@ class Invoice(models.Model):
     foreign_currency_rate = models.DecimalField(decimal_places=4, max_digits=10, null=True, blank=True)
     foreign_currency_rate_date = models.DateField(null=True, blank=True)
     file = models.FileField(null=True, blank=True, upload_to=invoice_filename)
+    internal_reference = models.TextField(blank=True)
 
     @staticmethod
     def _to_numeric_invoice_number(number):

src/pretix/base/models/orders.py

@@ -881,6 +881,11 @@ class InvoiceAddress(models.Model):
     vat_id = models.CharField(max_length=255, blank=True, verbose_name=_('VAT ID'),
                               help_text=_('Only for business customers within the EU.'))
     vat_id_validated = models.BooleanField(default=False)
+    internal_reference = models.TextField(
+        verbose_name=_('Internal reference'),
+        help_text=_('This reference will be printed on your invoice for your convenience.'),
+        blank=True
+    )
 
 
 def cachedticket_name(instance, filename: str) -> str:

src/pretix/base/services/invoices.py

@@ -54,13 +54,14 @@ def build_invoice(invoice: Invoice) -> Invoice:
 {i.zipcode} {i.city}
 {country}""")
             invoice.invoice_to = addr_template.format(
-                i=invoice.order.invoice_address,
-                country=invoice.order.invoice_address.country.name if invoice.order.invoice_address.country else invoice.order.invoice_address.country_old
+                i=ia,
+                country=ia.country.name if ia.country else ia.country_old
             ).strip()
-            if invoice.order.invoice_address.vat_id:
-                invoice.invoice_to += "\n" + pgettext("invoice", "VAT-ID: %s") % invoice.order.invoice_address.vat_id
+            invoice.internal_reference = ia.internal_reference
+            if ia.vat_id:
+                invoice.invoice_to += "\n" + pgettext("invoice", "VAT-ID: %s") % ia.vat_id
 
-            cc = str(invoice.order.invoice_address.country)
+            cc = str(ia.country)
 
             if cc in EU_CURRENCIES and EU_CURRENCIES[cc] != invoice.event.currency:
                 invoice.foreign_currency_display = EU_CURRENCIES[cc]