Refs #145 -- Vouchers that grant discounts

src/pretix/base/migrations/0048_auto_20161129_1330.py

@@ -0,0 +1,30 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.3 on 2016-11-29 13:30
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0047_auto_20161126_1300'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='voucher',
+            name='price_mode',
+            field=models.CharField(choices=[('none', 'No effect'), ('set', 'Set product price to'), ('subtract', 'Subtract from product price'), ('percent', 'Reduce product price by (%)')], default='set', max_length=100, verbose_name='Price mode'),
+        ),
+        migrations.RenameField(
+            model_name='voucher',
+            old_name='price',
+            new_name='value',
+        ),
+        migrations.AlterField(
+            model_name='voucher',
+            name='value',
+            field=models.DecimalField(blank=True, decimal_places=2, max_digits=10, null=True, verbose_name='Voucher value'),
+        ),
+    ]

src/pretix/base/models/vouchers.py

@@ -1,10 +1,13 @@
+from decimal import Decimal
+
 from django.conf import settings
 from django.core.exceptions import ValidationError
 from django.db import models
 from django.utils.crypto import get_random_string
 from django.utils.timezone import now
 from django.utils.translation import ugettext_lazy as _
 
+from ..decimal import round_decimal
 from .base import LoggedModel
 from .event import Event
 from .items import Item, ItemVariation, Quota
@@ -59,6 +62,13 @@ class Voucher(LoggedModel):
     * You need to either select a quota or an item
     * If you select an item that has variations but do not select a variation, you cannot set block_quota
     """
+    PRICE_MODES = (
+        ('none', _('No effect')),
+        ('set', _('Set product price to')),
+        ('subtract', _('Subtract from product price')),
+        ('percent', _('Reduce product price by (%)')),
+    )
+
     event = models.ForeignKey(
         Event,
         on_delete=models.CASCADE,
@@ -98,10 +108,15 @@ class Voucher(LoggedModel):
             "If activated, a holder of this voucher code can buy tickets, even if there are none left."
         )
     )
-    price = models.DecimalField(
-        verbose_name=_("Set product price to"),
+    price_mode = models.CharField(
+        verbose_name=_("Price mode"),
+        max_length=100,
+        choices=PRICE_MODES,
+        default='set'
+    )
+    value = models.DecimalField(
+        verbose_name=_("Voucher value"),
         decimal_places=2, max_digits=10, null=True, blank=True,
-        help_text=_('If empty, the product will cost its normal price.')
     )
     item = models.ForeignKey(
         Item, related_name='vouchers',
@@ -208,3 +223,19 @@ def is_active(self):
         if self.valid_until and self.valid_until < now():
             return False
         return True
+
+    def calculate_price(self, original_price: Decimal) -> Decimal:
+        """
+        Returns how the price given in original_price would be modified if this
+        voucher is applied, i.e. replaced by a different price or reduced by a
+        certain percentage. If the voucher does not modify the price, the
+        original price will be returned.
+        """
+        if self.value:
+            if self.price_mode == 'set':
+                return self.value
+            elif self.price_mode == 'subtract':
+                return original_price - self.value
+            elif self.price_mode == 'percent':
+                return round_decimal(original_price * (Decimal('100.00') - self.value) / Decimal('100.00'))
+        return original_price

src/pretix/base/services/cart.py

@@ -168,11 +168,10 @@ def _add_new_items(event: Event, items: List[dict],
                         err = err or error_messages['in_part']
                     quota_ok = min(quota_ok, avail[1])
 
-        if voucher and voucher.price is not None:
-            price = voucher.price
-        else:
-            price = item.default_price if variation is None else (
-                variation.default_price if variation.default_price is not None else item.default_price)
+        price = item.default_price if variation is None else (
+            variation.default_price if variation.default_price is not None else item.default_price)
+        if voucher:
+            price = voucher.calculate_price(price)
 
         if item.free_price and 'price' in i and i['price'] is not None and i['price'] != "":
             custom_price = i['price']

src/pretix/base/services/orders.py

@@ -233,8 +233,7 @@ def _check_positions(event: Event, now_dt: datetime, positions: List[CartPositio
                 err = err or error_messages['voucher_expired']
                 cp.delete()
                 continue
-            if cp.voucher.price is not None:
-                price = cp.voucher.price
+            price = cp.voucher.calculate_price(price)
 
         if price != cp.price and not (cp.item.free_price and cp.price > price):
             positions[i] = cp

src/pretix/control/forms/vouchers.py

@@ -22,8 +22,8 @@ class Meta:
         model = Voucher
         localized_fields = '__all__'
         fields = [
-            'code', 'valid_until', 'block_quota', 'allow_ignore_quota', 'price', 'tag',
-            'comment', 'max_usages'
+            'code', 'valid_until', 'block_quota', 'allow_ignore_quota', 'value', 'tag',
+            'comment', 'max_usages', 'price_mode'
         ]
         widgets = {
             'valid_until': forms.DateTimeInput(attrs={'class': 'datetimepicker'}),
@@ -187,8 +187,8 @@ class Meta:
         model = Voucher
         localized_fields = '__all__'
         fields = [
-            'valid_until', 'block_quota', 'allow_ignore_quota', 'price', 'tag', 'comment',
-            'max_usages'
+            'valid_until', 'block_quota', 'allow_ignore_quota', 'value', 'tag', 'comment',
+            'max_usages', 'price_mode'
         ]
         widgets = {
             'valid_until': forms.DateTimeInput(attrs={'class': 'datetimepicker'}),

src/pretix/control/templates/pretixcontrol/vouchers/bulk.html

@@ -33,7 +33,15 @@ <h1>{% trans "Create multiple voucher" %}</h1>
             {% bootstrap_field form.valid_until layout="horizontal" %}
             {% bootstrap_field form.block_quota layout="horizontal" %}
             {% bootstrap_field form.allow_ignore_quota layout="horizontal" %}
-            {% bootstrap_field form.price layout="horizontal" %}
+            <div class="form-group">
+                <label class="col-md-3 control-label" for="id_tag">{% trans "Price effect" %}</label>
+                <div class="col-md-5">
+                    {% bootstrap_field form.price_mode show_label=False form_group_class="" %}
+                </div>
+                <div class="col-md-4">
+                    {% bootstrap_field form.value show_label=False form_group_class="" %}
+                </div>
+            </div>
             {% bootstrap_field form.itemvar layout="horizontal" %}
             <div class="form-group">
                 <div class="col-md-9 col-md-offset-3">

src/pretix/control/templates/pretixcontrol/vouchers/detail.html

@@ -27,7 +27,15 @@ <h1>{% trans "Voucher" %}</h1>
             {% bootstrap_field form.valid_until layout="horizontal" %}
             {% bootstrap_field form.block_quota layout="horizontal" %}
             {% bootstrap_field form.allow_ignore_quota layout="horizontal" %}
-            {% bootstrap_field form.price layout="horizontal" %}
+            <div class="form-group">
+                <label class="col-md-3 control-label" for="id_tag">{% trans "Price effect" %}</label>
+                <div class="col-md-5">
+                    {% bootstrap_field form.price_mode show_label=False form_group_class="" %}
+                </div>
+                <div class="col-md-4">
+                    {% bootstrap_field form.value show_label=False form_group_class="" %}
+                </div>
+            </div>
             {% bootstrap_field form.itemvar layout="horizontal" %}
             <div class="form-group">
                 <div class="col-md-9 col-md-offset-3">

src/pretix/control/views/vouchers.py

@@ -59,7 +59,7 @@ def _download_csv(self):
 
         headers = [
             _('Voucher code'), _('Valid until'), _('Product'), _('Reserve quota'), _('Bypass quota'),
-            _('Price'), _('Tag'), _('Redeemed'), _('Maximum usages')
+            _('Price effect'), _('Value'), _('Tag'), _('Redeemed'), _('Maximum usages')
         ]
         writer.writerow(headers)
 
@@ -77,7 +77,8 @@ def _download_csv(self):
                 prod,
                 _("Yes") if v.block_quota else _("No"),
                 _("Yes") if v.allow_ignore_quota else _("No"),
-                str(v.price) if v.price else "",
+                v.get_price_mode_display(),
+                str(v.value) if v.value else "",
                 v.tag,
                 str(v.redeemed),
                 str(v.max_usages)

src/pretix/presale/views/cart.py

@@ -198,20 +198,16 @@ def get_context_data(self, **kwargs):
                     item.cached_availability = (Quota.AVAILABILITY_OK, 1)
                 else:
                     item.cached_availability = item.check_quotas()
-                if self.voucher.price is not None:
-                    item.price = self.voucher.price
-                else:
-                    item.price = item.default_price
+                item.price = self.voucher.calculate_price(item.default_price)
             else:
                 for var in item.available_variations:
                     if self.voucher.allow_ignore_quota or self.voucher.block_quota:
                         var.cached_availability = (Quota.AVAILABILITY_OK, 1)
                     else:
                         var.cached_availability = list(var.check_quotas())
-                    if self.voucher.price is not None:
-                        var.price = self.voucher.price
-                    else:
-                        var.price = var.default_price if var.default_price is not None else item.default_price
+                    var.price = self.voucher.calculate_price(
+                        var.default_price if var.default_price is not None else item.default_price
+                    )
 
                 if len(item.available_variations) > 0:
                     item.min_price = min([v.price for v in item.available_variations])

src/tests/base/test_models.py

@@ -1,6 +1,7 @@
 import datetime
 import sys
 from datetime import timedelta
+from decimal import Decimal
 
 import pytest
 from django.conf import settings
@@ -406,6 +407,29 @@ def test_voucher_no_item_but_variation(self):
             v.clean()
 
 
+class VoucherTestCase(BaseQuotaTestCase):
+
+    def test_calculate_price_none(self):
+        v = Voucher.objects.create(event=self.event, price_mode='none', value=Decimal('10.00'))
+        v.calculate_price(Decimal('23.42')) == Decimal('23.42')
+
+    def test_calculate_price_set_empty(self):
+        v = Voucher.objects.create(event=self.event, price_mode='set')
+        v.calculate_price(Decimal('23.42')) == Decimal('23.42')
+
+    def test_calculate_price_set(self):
+        v = Voucher.objects.create(event=self.event, price_mode='set', value=Decimal('10.00'))
+        v.calculate_price(Decimal('23.42')) == Decimal('10.00')
+
+    def test_calculate_price_subtract(self):
+        v = Voucher.objects.create(event=self.event, price_mode='subtract', value=Decimal('10.00'))
+        v.calculate_price(Decimal('23.42')) == Decimal('13.42')
+
+    def test_calculate_price_percent(self):
+        v = Voucher.objects.create(event=self.event, price_mode='percent', value=Decimal('23.00'))
+        v.calculate_price(Decimal('100.00')) == Decimal('77.00')
+
+
 class OrderTestCase(BaseQuotaTestCase):
     def setUp(self):
         super().setUp()

src/tests/control/test_vouchers.py

@@ -80,9 +80,9 @@ def test_list(self):
     def test_csv(self):
         self.event.vouchers.create(item=self.ticket, code='ABCDEFG')
         doc = self.client.get('/control/event/%s/%s/vouchers/?download=yes' % (self.orga.slug, self.event.slug))
-        assert doc.content.strip() == '"Voucher code","Valid until","Product","Reserve quota","Bypass quota","Price",' \
-                                      '"Tag","Redeemed","Maximum usages"\r\n"ABCDEFG","","Early-bird ticket","No",' \
-                                      '"No","","","0","1"'.encode('utf-8')
+        assert doc.content.strip() == '"Voucher code","Valid until","Product","Reserve quota","Bypass quota",' \
+                                      '"Price effect","Value","Tag","Redeemed","Maximum usages"\r\n"ABCDEFG","",' \
+                                      '"Early-bird ticket","No","No","Set product price to","","","0","1"'.encode('utf-8')
 
     def test_filter_status_valid(self):
         v = self.event.vouchers.create(item=self.ticket)