add website_membership_signup_required: force to create user before add to cart a membership product

website_membership_signup_required/models/website.py

@@ -0,0 +1,33 @@
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import fields, models
+
+
+class Website(models.Model):
+    _inherit = "website"
+
+    membership_signup_required = fields.Boolean(
+        string="Force signup for membership products",
+        help="When enabled, anonymous users trying to add a membership product "
+             "to cart are redirected to /web/signup before the product is "
+             "added. Only affects the e-commerce flow.",
+        default=True,
+    )
+
+    def _membership_signup_required_for(self, product_id, is_public):
+        """Decide whether the given `product_id` requires forcing a signup
+        step before it can be added to cart by an anonymous visitor.
+
+        Centralised here (model layer) so it can be unit-tested without HTTP
+        and reused by future extensions. The controller delegates to this
+        helper.
+        """
+        self.ensure_one()
+        if not self.membership_signup_required:
+            return False
+        if not is_public:
+            return False
+        if not product_id:
+            return False
+        product = self.env["product.product"].sudo().browse(int(product_id)).exists()
+        return bool(product and product.product_tmpl_id.membership)