odoo-membership-addons/membership_initial_discount/models/product_template.py

# License AGPL-3 - See https://www.gnu.org/licenses/agpl-3.0
from odoo import models, fields, api, _
from odoo.exceptions import ValidationError

DISCOUNTS = [
    ("none", "No initial discount"),
    ("fixed", "Fixed amount"),
    ("percent", "Percentage of the price"),
]


class ProductTemplate(models.Model):
    _inherit = "product.template"

    initial_discount = fields.Selection(
        selection=DISCOUNTS,
        default="none",
        string="Initial discount",
        required=True,
    )
    fixed_discount = fields.Float(
        string="Discount amount",
        digits="Product Price",
    )
    percent_discount = fields.Float(
        string="Discount (%)",
        digits=(12, 2),
    )

    @api.constrains("list_price", "initial_discount", "fixed_discount")
    def check_fixed_discount(self):
        for product in self:
            if (
                product.initial_discount == "fixed"
                and product.list_price <= product.fixed_discount
            ):
                raise ValidationError(
                    _(
                        "Fixed discount for 1st membership must be less than the product template, or any of its variants, sale price."
                    )
                )

    @api.constrains("initial_discount", "percent_discount")
    def check_percent_discount(self):
        for product in self:
            if product.initial_discount == "percent" and product.percent_discount < 0.0:
                raise ValidationError(
                    _(
                        'Percent discount cannot handle a negative value.\nIf you wan to apply extra fees, please install "Membership initial fee" module (OCA/vertical-association)'
                    )
                )
            elif (
                product.initial_discount == "percent"
                and product.percent_discount >= 100.0
            ):
                raise ValidationError(
                    _("Percent discount must handle a value smaller than 100%.")
                )