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

website_membership_signup_required/static/src/js/website_membership_signup_required.js

@@ -0,0 +1,41 @@
+/** @odoo-module **/
+
+// Force-redirect handler for the membership signup flow.
+//
+// The `cart_update_json` controller override returns
+// `{ force_redirect: <signup_url> }` when an anonymous visitor tries to add a
+// membership product to the cart in "stay on page" mode
+// (`website.add_to_cart_action == 'stay'`), which is the JSON path used by
+// `_addToCartInPage` in the core `WebsiteSale` widget. The core handler only
+// reads `cart_quantity` / `notification_info` from that response and would
+// otherwise ignore `force_redirect`, leaving the membership intercept as a
+// silent no-op for the JSON path.
+//
+// The standard `#add_to_cart` button on the product page posts to
+// `/shop/cart/update` (HTTP), handled by `cart_update`, which already raises
+// an HTTP redirect — that path is unaffected here.
+//
+// Why a front-end handler and not an HTTP redirect raised from the controller:
+// `_addToCartInPage` calls `rpc("/shop/cart/update_json", ...)` and `rpc` does
+// `fetch(...).then(r => r.json())` with the default `redirect: "follow"`. A
+// `werkzeug.exceptions.Redirect` (3xx) from the JSON route would be silently
+// followed by `fetch`, the `/web/signup` HTML would be parsed as JSON, and the
+// frontend would break with an uncaught error. The front-end handler is
+// therefore the standard, non-intrusive approach (only acts when
+// `data.force_redirect` exists).
+
+import "@website_sale/js/website_sale";
+import publicWidget from "@web/legacy/js/public/public_widget";
+
+publicWidget.registry.WebsiteSale.include({
+    /**
+     * @override
+     */
+    async _addToCartInPage(params) {
+        const data = await this._super.apply(this, arguments);
+        if (data && data.force_redirect) {
+            window.location.href = data.force_redirect;
+        }
+        return data;
+    },
+});