pretix_cgo/src/pretix/api/serializers/__init__.py

#
# This file is part of pretix (Community Edition).
#
# Copyright (C) 2014-2020  Raphael Michel and contributors
# Copyright (C) 2020-today pretix GmbH and contributors
#
# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
# Public License as published by the Free Software Foundation in version 3 of the License.
#
# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
# this file, see <https://pretix.eu/about/en/license>.
#
# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
# <https://www.gnu.org/licenses/>.
#
import json
import re

from django.db.models import prefetch_related_objects
from rest_framework import serializers
from rest_framework.exceptions import ValidationError


class AsymmetricField(serializers.Field):
    def __init__(self, read, write, **kwargs):
        self.read = read
        self.write = write
        super().__init__(
            required=self.write.required,
            default=self.write.default,
            initial=self.write.initial,
            source=self.write.source if self.write.source != self.write.field_name else None,
            label=self.write.label,
            allow_null=self.write.allow_null,
            error_messages=self.write.error_messages,
            validators=self.write.validators,
            **kwargs
        )

    def to_internal_value(self, data):
        return self.write.to_internal_value(data)

    def to_representation(self, value):
        return self.read.to_representation(value)

    def run_validation(self, data=serializers.empty):
        return self.write.run_validation(data)


class CompatibleJSONField(serializers.JSONField):
    def to_internal_value(self, data):
        try:
            return json.dumps(data)
        except (TypeError, ValueError):
            self.fail('invalid')

    def to_representation(self, value):
        if value:
            return json.loads(value)
        return value


class SalesChannelMigrationMixin:
    """
    Translates between the old field "sales_channels" and the new field combo "all_sales_channels"/"limit_sales_channels".
    """

    @property
    def organizer(self):
        if "organizer" in self.context:
            return self.context["organizer"]
        elif "event" in self.context:
            return self.context["event"].organizer
        else:
            raise ValueError("organizer not in context")

    def to_internal_value(self, data):
        if "sales_channels" in data:
            if data["sales_channels"] is None:
                raise ValidationError({
                    "sales_channels": [
                        "The legacy attribute 'sales_channels' cannot be set to None, it must be a list."
                    ]
                })

            prefetch_related_objects([self.organizer], "sales_channels")
            all_channels = {
                s.identifier for s in
                self.organizer.sales_channels.all()
            }

            if data.get("all_sales_channels") and set(data["sales_channels"]) != all_channels:
                raise ValidationError({
                    "all_sales_channels": [
                        "If 'all_sales_channels' is set, the legacy attribute 'sales_channels' must not be set or set to "
                        "the list of all sales channels."
                    ]
                })

            if data.get("limit_sales_channels") and set(data["sales_channels"]) != set(data["limit_sales_channels"]):
                raise ValidationError({
                    "limit_sales_channels": [
                        "If 'limit_sales_channels' is set, the legacy attribute 'sales_channels' must not be set or set to "
                        "the same list."
                    ]
                })

            if set(data["sales_channels"]) == all_channels:
                data["all_sales_channels"] = True
                data["limit_sales_channels"] = []
            else:
                data["all_sales_channels"] = False
                data["limit_sales_channels"] = data["sales_channels"]

            del data["sales_channels"]

        if data.get("all_sales_channels"):
            data["limit_sales_channels"] = []

        return super().to_internal_value(data)

    def to_representation(self, value):
        value = super().to_representation(value)
        if value.get("all_sales_channels"):
            prefetch_related_objects([self.organizer], "sales_channels")
            value["sales_channels"] = sorted([
                s.identifier for s in
                self.organizer.sales_channels.all()
            ])
        else:
            value["sales_channels"] = value["limit_sales_channels"]
        return value


class CompatDecimalField(serializers.DecimalField):
    """
    Historically, pretix recorded tax rates as decimals with two places. Today, pretix supports tax rates with up to
    four places. Since our API outputs decimals with the stored precision, this would have changed the API output from
    "19.00" to "19.0000" without warning. While this is semantically the same thing, we need to assume some pretix API
    users might run into trouble, either because they treat the value as a string and then map something
    (e.g. ``if tax_rate == "19.00"``) or process it with a language where this is a significant difference. For example,
    while in Python ``Decimal("19.00") == Decimal("19.0000")`` is true, in Java
    ``(new BigDecimal("19.00")).equals(new BigDecimal("19.0000"))`` is false and only
    ``(new BigDecimal("19.00")).compareTo(new BigDecimal("19.0000")) == 0`` is true.

    Therefore, we stay backwards compatible by outputting two decimal places *as long as the trailing digits are zero-valued.
    """

    regex = re.compile(r"^([0-9]+\.[0-9]{2})0+$")

    def to_representation(self, value):
        if self.localize:
            raise ValueError("localization not supported")
        value = super().to_representation(value)
        if value and "." not in value:
            return f"{value}.00"
        if m := self.regex.match(value):
            return m.group(1)
        return value