Re-work API for payment settings fields

src/pretix/base/payment.py

@@ -1,8 +1,12 @@
+from collections import OrderedDict
 from decimal import Decimal
+from django import forms
 
 from django.forms import Form
 from django.template import Context
 from django.template.loader import get_template
+from django.utils.translation import ugettext_lazy as _
+from pretix.base.forms import SettingsForm
 
 from pretix.base.settings import SettingsSandbox
 
@@ -20,45 +24,74 @@ class BasePaymentProvider:
         return self.identifier
 
     @property
-    def is_enabled(self):
+    def is_enabled(self) -> bool:
         """
         Returns, whether or whether not this payment provider is enabled.
-        By default, this is determined by the value of a setting.
+        By default, this is determined by the value of the ``_enabled`` setting.
         """
         return self.settings.get('_enabled', as_type=bool)
 
-    def calculate_fee(self, price):
+    def calculate_fee(self, price: Decimal) -> Decimal:
         """
         Calculate the fee for this payment provider which will be added to
-        the final price if the price before fees (but after taxes) is 'price'.
+        final price before fees (but after taxes). It should include any taxes.
+        The default implementation makes use of the setting ``_fee_abs`` for an
+        absolute fee and ``_fee_percent`` for a percentage.
+
+        :param price: The total value without the payment method fee, after taxes.
         """
         fee_abs = self.settings.get('_fee_abs', as_type=Decimal, default=0)
         fee_percent = self.settings.get('_fee_percent', as_type=Decimal, default=0)
-        return price * fee_percent / 100 + fee_abs
+        return Decimal(price * fee_percent / 100 + fee_abs)
 
     @property
     def verbose_name(self) -> str:
         """
-        A human-readable name for this payment provider
+        A human-readable name for this payment provider. This should
+        be short but self-explaining. Good examples include 'Bank transfer'
+        and 'Credit card via Stripe'.
         """
         raise NotImplementedError()  # NOQA
 
     @property
     def identifier(self) -> str:
         """
-        A unique identifier for this payment provider
+        A short and unique identifier for this payment provider.
+        This should only contain lowercase letters and in most
+        cases will be the same as your packagename.
         """
         raise NotImplementedError()  # NOQA
 
     @property
     def settings_form_fields(self) -> dict:
         """
+        When the event's administrator administrator visits the event configuration
+        page,
         A dictionary. The keys should be (unprefixed) EventSetting keys,
         the values should be corresponding django form fields.
 
         We suggest returning a collections.OrderedDict object instead of a dict.
         """
-        raise NotImplementedError()  # NOQA
+        return OrderedDict([
+            ('_enabled',
+             forms.ChoiceField(
+                 label=_('Enable payment method'),
+                 required=False,
+                 choices=SettingsForm.BOOL_CHOICES,
+             )),
+            ('_fee_abs',
+             forms.DecimalField(
+                 label=_('Additional fee'),
+                 help_text=_('Absolute value'),
+                 required=False
+             )),
+            ('_fee_percent',
+             forms.DecimalField(
+                 label=_('Additional fee'),
+                 help_text=_('Percentage'),
+                 required=False
+             )),
+        ])
 
     @property
     def checkout_form_fields(self) -> dict:

src/pretix/control/views/event.py

@@ -129,25 +129,6 @@ class PaymentSettings(EventPermissionRequiredMixin, TemplateView, SingleObjectMi
             )
             provider.form.fields = OrderedDict(
                 [
-                    ('payment_%s__enabled' % provider.identifier,
-                     forms.ChoiceField(
-                         label=_('Enable payment method'),
-                         required=False,
-                         choices=SettingsForm.BOOL_CHOICES,
-                     )),
-                    ('payment_%s__fee_abs' % provider.identifier,
-                     forms.DecimalField(
-                         label=_('Additional fee'),
-                         help_text=_('Absolute value'),
-                         required=False
-                     )),
-                    ('payment_%s__fee_percent' % provider.identifier,
-                     forms.DecimalField(
-                         label=_('Additional fee'),
-                         help_text=_('Percentage'),
-                         required=False
-                     )),
-                ] + [
                     ('payment_%s_%s' % (provider.identifier, k), v)
                     for k, v in provider.settings_form_fields.items()
                 ]

src/pretix/plugins/banktransfer/payment.py

@@ -10,14 +10,19 @@ from pretix.base.payment import BasePaymentProvider
 class BankTransfer(BasePaymentProvider):
     identifier = 'banktransfer'
     verbose_name = _('Bank transfer')
-    settings_form_fields = OrderedDict([
-        ('bank_details',
-         forms.CharField(
-             widget=forms.Textarea,
-             label=_('Bank account details'),
-             required=False
-         ))
-    ])
+
+    @property
+    def settings_form_fields(self):
+        return OrderedDict(
+            list(super().settings_form_fields.items()) + [
+                ('bank_details',
+                 forms.CharField(
+                     widget=forms.Textarea,
+                     label=_('Bank account details'),
+                     required=False
+                 ))
+            ]
+        )
 
     def checkout_form_render(self, request) -> str:
         template = get_template('pretixplugins/banktransfer/checkout_payment_form.html')

src/pretix/plugins/paypal/payment.py

@@ -22,31 +22,36 @@ class Paypal(BasePaymentProvider):
 
     identifier = 'paypal'
     verbose_name = _('PayPal')
-    settings_form_fields = OrderedDict([
-        ('endpoint',
-         forms.ChoiceField(
-             label=_('Endpoint'),
-             initial='live',
-             choices=(
-                 ('live', 'Live'),
-                 ('sandbox', 'Sandbox'),
-             ),
-             required=False
-         )),
-        ('client_id',
-         forms.CharField(
-             label=_('Client ID'),
-             required=False
-         )),
-        ('secret',
-         forms.CharField(
-             label=_('Secret'),
-             required=False
-         ))
-    ])
     checkout_form_fields = OrderedDict([
     ])
 
+    @property
+    def settings_form_fields(self):
+        return OrderedDict(
+            list(super().settings_form_fields.items()) + [
+                ('endpoint',
+                 forms.ChoiceField(
+                     label=_('Endpoint'),
+                     initial='live',
+                     choices=(
+                         ('live', 'Live'),
+                         ('sandbox', 'Sandbox'),
+                     ),
+                     required=False
+                 )),
+                ('client_id',
+                 forms.CharField(
+                     label=_('Client ID'),
+                     required=False
+                 )),
+                ('secret',
+                 forms.CharField(
+                     label=_('Secret'),
+                     required=False
+                 ))
+            ]
+        )
+
     def init_api(self):
         paypalrestsdk.set_config(
             mode="sandbox" if "sandbox" in self.settings.get('endpoint') else 'live',

src/pretix/plugins/stripe/payment.py

@@ -8,8 +8,6 @@ from pretix.base.payment import BasePaymentProvider
 class Stripe(BasePaymentProvider):
     identifier = 'stripe'
     verbose_name = _('Credit Card via Stripe')
-    settings_form_fields = OrderedDict([
-    ])
     checkout_form_fields = OrderedDict([
         ('cc_number',
          forms.CharField(