[ADD] user friendly error handling for restricted qty on ecommerce app

sale_restricted_qty_website_sale/__init__.py

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+from . import models

sale_restricted_qty_website_sale/__manifest__.py

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+# Copyright 2026 Elabore ()
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+{
+    "name": "sale_restricted_qty_website_sale",
+    "version": "16.0.1.0.0",
+    "author": "Elabore",
+    "website": "https://elabore.coop",
+    "maintainer": "Elabore",
+    "license": "AGPL-3",
+    "category": "Sales",
+    "summary": "Improve UX handling on e-commerce product page",
+    # any module necessary for this one to work correctly
+    "depends": [
+        "sale_restricted_qty","website_sale",
+    ],
+    "qweb": [],
+    "external_dependencies": {
+        "python": [],
+    },
+    # always loaded
+    "data": [
+        "views/restricted_qty_website_sale_view.xml"
+    ],
+    "assets": {
+        "web.assets_frontend": [
+            "sale_restricted_qty_website_sale/static/src/js/add_to_cart.js",
+        ],
+    },
+    "installable": True,
+    # Install this module automatically if all dependency have been previously
+    # and independently installed.  Used for synergetic or glue modules.
+    "auto_install": True,
+    "application": False,
+}

sale_restricted_qty_website_sale/i18n/fr.po

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+# Translation of Odoo Server.
+# This file contains the translation of the following modules:
+# 	* elabore_website_sale_restricted_qty
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Odoo Server 16.0\n"
+"Report-Msgid-Bugs-To: \n"
+"PO-Revision-Date: 2026-08-18 00:00+0000\n"
+"Last-Translator: Élabore <https://elabore.coop>\n"
+"Language-Team: \n"
+"Language: fr\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n > 1);\n"
+
+#. module: elabore_website_sale_restricted_qty
+#. odoo-python
+#: code:addons/elabore_website_sale_restricted_qty/models/sale_order_line.py:0
+#, python-format
+msgid ""
+"The selected quantity is not available for sale:\n"
+"\n"
+"%s\n"
+"\n"
+"Please adjust the quantity."
+msgstr ""
+"La quantité choisie n'est pas disponible à la vente :\n"
+"\n"
+"%s\n"
+"\n"
+"Merci d'ajuster la quantité."
+
+#. module: elabore_website_sale_restricted_qty
+#. odoo-python
+#: code:addons/elabore_website_sale_restricted_qty/models/sale_order_line.py:0
+#, python-format
+msgid "%(product)s: minimum order quantity is %(qty)s."
+msgstr "%(product)s : quantité minimum de commande %(qty)s."
+
+#. module: elabore_website_sale_restricted_qty
+#. odoo-python
+#: code:addons/elabore_website_sale_restricted_qty/models/sale_order_line.py:0
+#, python-format
+msgid "%(product)s: maximum order quantity is %(qty)s."
+msgstr "%(product)s : quantité maximum de commande %(qty)s."
+
+#. module: elabore_website_sale_restricted_qty
+#. odoo-python
+#: code:addons/elabore_website_sale_restricted_qty/models/sale_order_line.py:0
+#, python-format
+msgid "%(product)s: must be ordered in multiples of %(qty)s."
+msgstr "%(product)s : à commander par multiples de %(qty)s."
+
+#. module: elabore_website_sale_restricted_qty
+#. odoo-python
+#: code:addons/elabore_website_sale_restricted_qty/models/product_restricted_qty_mixin.py:0
+#, python-format
+msgid "minimum order: %(qty)s %(uom)s"
+msgstr "commande minimum : %(qty)s %(uom)s"
+
+#. module: elabore_website_sale_restricted_qty
+#. odoo-python
+#: code:addons/elabore_website_sale_restricted_qty/models/product_restricted_qty_mixin.py:0
+#, python-format
+msgid "in multiples of %(qty)s %(uom)s"
+msgstr "par multiples de %(qty)s %(uom)s"
+
+#. module: elabore_website_sale_restricted_qty
+#. odoo-python
+#: code:addons/elabore_website_sale_restricted_qty/models/product_restricted_qty_mixin.py:0
+#, python-format
+msgid "maximum: %(qty)s %(uom)s"
+msgstr "maximum : %(qty)s %(uom)s"
+
+#. module: elabore_website_sale_restricted_qty
+#: model:ir.ui.view,name:elabore_website_sale_restricted_qty.product_restricted_qty_info
+msgid "Restricted Quantity Information"
+msgstr "Information sur les quantités restreintes"

sale_restricted_qty_website_sale/models/__init__.py

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+from . import product_restricted_qty_mixin
+from . import sale_order_line

sale_restricted_qty_website_sale/models/product_restricted_qty_mixin.py

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+# Copyright 2026 Élabore (https://elabore.coop)
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import _, models
+from odoo.tools import float_is_zero
+from odoo.tools.misc import formatLang
+
+
+class ProductRestrictedQtyMixin(models.AbstractModel):
+    """Extending the OCA abstract mixin makes these helpers available at once
+    on product.product, product.template and product.category."""
+
+    _inherit = "product.restricted.qty.mixin"
+
+    def _format_restricted_qty(self, qty):
+        """Short form: 6 rather than 6.0, and a locale-aware separator
+        for decimals."""
+        if float_is_zero(qty - int(qty), precision_digits=3):
+            return str(int(qty))
+        return formatLang(self.env, qty)
+
+    def _get_restricted_qty_hint(self):
+        """Sentence shown to the customer. Empty when nothing restricts him.
+
+        OCA semantics: `force_sale_min_qty` / `force_sale_max_qty` set to Yes
+        make the bound purely indicative -- the constraint does not block, so
+        we announce nothing rather than promising a rule that does not exist.
+        """
+        self.ensure_one()
+        uom = self.uom_id.name if "uom_id" in self._fields else ""
+        parts = []
+        if self.sale_min_qty and not self.force_sale_min_qty:
+            parts.append(
+                _(
+                    "minimum order: %(qty)s %(uom)s",
+                    qty=self._format_restricted_qty(self.sale_min_qty),
+                    uom=uom,
+                )
+            )
+        if self.sale_multiple_qty:
+            parts.append(
+                _(
+                    "in multiples of %(qty)s %(uom)s",
+                    qty=self._format_restricted_qty(self.sale_multiple_qty),
+                    uom=uom,
+                )
+            )
+        if self.sale_max_qty and not self.force_sale_max_qty:
+            parts.append(
+                _(
+                    "maximum: %(qty)s %(uom)s",
+                    qty=self._format_restricted_qty(self.sale_max_qty),
+                    uom=uom,
+                )
+            )
+        if not parts:
+            return ""
+        hint = " · ".join(parts)
+        return hint[0].upper() + hint[1:]

sale_restricted_qty_website_sale/models/sale_order_line.py

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+from odoo import _, api, models
+from odoo.exceptions import ValidationError
+
+
+class SaleOrderLine(models.Model):
+    _inherit = "sale.order.line"
+
+    @api.constrains(
+        "product_uom_qty", "sale_min_qty", "sale_max_qty", "sale_multiple_qty"
+    )
+    def check_constraint_restricted_qty(self):
+        """Rewrite the error message raised by `sale_restricted_qty`.
+
+        The upstream message is written for a salesperson: it dumps the
+        offending products and explains how to tick "force min quantity" on
+        the product form. Unreadable for an eCommerce customer.
+
+        Detection is left to the OCA module -- the `is_qty_*` fields stay the
+        single source of truth. Only the wording is replaced, so an upstream
+        change to the rules is followed without breaking anything.
+        """
+        try:
+            return super().check_constraint_restricted_qty()
+        except ValidationError:
+            raise ValidationError(self._get_restricted_qty_error_message()) from None
+
+    def _get_restricted_qty_error_message(self):
+        """Customer-facing message, one line per unmet restriction."""
+        details = []
+        for line in self:
+            product = line.product_id
+            if not product.force_sale_min_qty and line.is_qty_less_min_qty:
+                details.append(
+                    _(
+                        "%(product)s: minimum order quantity is %(qty)s.",
+                        product=product.display_name,
+                        qty=product._format_restricted_qty(line.sale_min_qty),
+                    )
+                )
+            if not product.force_sale_max_qty and line.is_qty_bigger_max_qty:
+                details.append(
+                    _(
+                        "%(product)s: maximum order quantity is %(qty)s.",
+                        product=product.display_name,
+                        qty=product._format_restricted_qty(line.sale_max_qty),
+                    )
+                )
+            if line.is_qty_not_multiple_qty:
+                details.append(
+                    _(
+                        "%(product)s: must be ordered in multiples of %(qty)s.",
+                        product=product.display_name,
+                        qty=product._format_restricted_qty(line.sale_multiple_qty),
+                    )
+                )
+
+        return _(
+            "The selected quantity is not available for sale:\n\n"
+            "%s\n\n"
+            "Please adjust the quantity.",
+            "\n".join(details),
+        )

sale_restricted_qty_website_sale/static/src/js/add_to_cart.js

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+odoo.define("sale_restricted_qty_website_sale.add_to_cart", function (require) {
+    "use strict";
+
+    const publicWidget = require("web.public.widget");
+    const wSaleUtils = require("website_sale.utils");
+    const WebsiteSale = require("website_sale.website_sale").WebsiteSale;
+
+    WebsiteSale.include({
+        /**
+         *
+         * @override
+         */
+        _addToCartInPage: function () {
+            return this._super.apply(this, arguments).catch((error) => {
+                const message = this._getRestrictedQtyMessage(error);
+                if (!message) {
+                    // Not a quantity restriction: let the real error surface.
+                    return Promise.reject(error);
+                }
+                if (error && error.event && error.event.preventDefault) {
+                    // Legacy convention: tells the crash manager the error is
+                    // handled, so it does not open its own dialog on top.
+                    error.event.preventDefault();
+                }
+                wSaleUtils.showWarning(message);
+            });
+        },
+ 
+        /**
+         * @private
+         * @param {Object} error rejection from the legacy RPC
+         * @returns {string|false} the message, or false to re-throw
+         */
+        _getRestrictedQtyMessage: function (error) {
+            const data =
+                (error && error.message && error.message.data) ||
+                (error && error.data);
+            if (!data || data.name !== "odoo.exceptions.ValidationError") {
+                return false;
+            }
+            return data.message;
+        },
+    });
+
+});

sale_restricted_qty_website_sale/tests/__init__.py

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+from . import test_restricted_qty_website_sale

sale_restricted_qty_website_sale/tests/test_restricted_qty_website_sale.py

@@ -0,0 +1,89 @@
+from lxml import html
+
+from odoo.exceptions import ValidationError
+from odoo.tests import HttpCase, tagged
+
+from odoo.addons.http_routing.models.ir_http import slug
+
+
+@tagged("post_install", "-at_install")
+class TestRestrictedQtyInfo(HttpCase):
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.partner = cls.env["res.partner"].create({"name": "eCommerce customer"})
+        cls.product_min = cls._create_product(
+            "Product min 6", manual_sale_min_qty=6.0
+        )
+        cls.product_free = cls._create_product("Unrestricted product")
+        # force = Yes -> purely indicative bound, nothing to tell the customer
+        cls.product_indicative = cls._create_product(
+            "Product min 6 indicative",
+            manual_sale_min_qty=6.0,
+            manual_force_sale_min_qty="force",
+        )
+
+    @classmethod
+    def _create_product(cls, name, **restrictions):
+        values = {
+            "name": name,
+            "type": "consu",
+            "list_price": 10.0,
+            "sale_ok": True,
+            "is_published": True,
+        }
+        values.update(restrictions)
+        return cls.env["product.template"].create(values).product_variant_id
+
+    # ------------------------------------------------------------------
+    # Error message
+    # ------------------------------------------------------------------
+
+    def _create_line(self, product, qty):
+        order = self.env["sale.order"].create({"partner_id": self.partner.id})
+        self.env["sale.order.line"].create(
+            {
+                "order_id": order.id,
+                "product_id": product.id,
+                "product_uom_qty": qty,
+            }
+        )
+        # @api.constrains are evaluated on flush, not on create().
+        self.env.flush_all()
+        return order
+
+    def test_error_message_is_customer_facing(self):
+        with self.assertRaises(ValidationError) as error:
+            self._create_line(self.product_min, 1)
+
+        message = str(error.exception)
+        self.assertIn("Product min 6", message)
+        self.assertIn("6", message)
+        self.assertNotIn("force min", message, "Upstream jargon still present")
+
+    def test_valid_quantity_raises_nothing(self):
+        self._create_line(self.product_min, 6)
+
+    def test_indicative_minimum_still_does_not_block(self):
+        self._create_line(self.product_indicative, 1)
+
+    # ------------------------------------------------------------------
+    # Product page display
+    # ------------------------------------------------------------------
+
+    def _hint_on_page(self, product):
+        response = self.url_open("/shop/%s" % slug(product.product_tmpl_id))
+        self.assertEqual(response.status_code, 200)
+        tree = html.fromstring(response.content)
+        return tree.xpath("//div[contains(@class, 'o_wsale_qty_restriction')]")
+
+    def test_hint_is_displayed(self):
+        hint = self._hint_on_page(self.product_min)
+        self.assertEqual(len(hint), 1)
+        self.assertIn("6", hint[0].text_content())
+
+    def test_no_hint_without_restriction(self):
+        self.assertFalse(self._hint_on_page(self.product_free))
+
+    def test_no_hint_for_an_indicative_minimum(self):
+        self.assertFalse(self._hint_on_page(self.product_indicative))

sale_restricted_qty_website_sale/views/restricted_qty_website_sale_view.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+
+    <!-- Product page: tell the customer about the orderable quantities,
+         right below the quantity selector and the add-to-cart button. -->
+    <template id="product_restricted_qty_info"
+              inherit_id="website_sale.product_quantity"
+              name="Restricted Quantity Information">
+        <xpath expr="//div[@id='add_to_cart_wrap']" position="after">
+            <t t-set="qty_hint" t-value="product._get_restricted_qty_hint()"/>
+            <div t-if="qty_hint"
+                 class="o_wsale_qty_restriction alert alert-info d-flex align-items-center w-100 mt-2 mb-0 py-2 px-3">
+                <i class="fa fa-info-circle me-2" role="img" aria-label="Information"/>
+                <span t-out="qty_hint"/>
+            </div>
+        </xpath>
+    </template>
+
+</odoo>