Allow buttons to reuse cart (Z#23226853) (#6047)

* Allow buttons to reuse cart (Z#23226853)

* Always keep cart of buttons with items set

src/pretix/presale/urls.py

@@ -91,6 +91,9 @@ event_patterns = [
     re_path(r'w/(?P<cart_namespace>[a-zA-Z0-9]{16})/cart/add',
             csrf_exempt(pretix.presale.views.cart.CartAdd.as_view()),
             name='event.cart.add'),
+    re_path(r'w/(?P<cart_namespace>[a-zA-Z0-9]{16})/cart/create',
+            csrf_exempt(pretix.presale.views.cart.CartCreate.as_view()),
+            name='event.cart.create'),
 
     re_path(r'unlock/(?P<hash>[a-z0-9]{64})/$', pretix.presale.views.user.UnlockHashView.as_view(),
             name='event.payment.unlock'),

src/pretix/presale/views/cart.py

@@ -555,6 +555,18 @@ class CartClear(EventViewMixin, CartActionMixin, AsyncAction, View):
                        request.sales_channel.identifier, time_machine_now(default=None))
 
 
+@method_decorator(allow_cors_if_namespaced, 'dispatch')
+class CartCreate(EventViewMixin, CartActionMixin, View):
+    def get(self, request, *args, **kwargs):
+        if 'ajax' in self.request.GET:
+            cart_id = get_or_create_cart_id(self.request, create=True)
+            return JsonResponse({
+                'cart_id': cart_id,
+            })
+        else:
+            return redirect_to_url(self.get_success_url())
+
+
 @method_decorator(allow_frame_if_namespaced, 'dispatch')
 class CartExtendReservation(EventViewMixin, CartActionMixin, AsyncAction, View):
     task = extend_cart_reservation

src/pretix/static/pretixpresale/js/widget/widget.js

@@ -110,6 +110,10 @@ var setCookie = function (cname, cvalue, exdays) {
     var d = new Date();
     d.setTime(d.getTime() + (exdays * 24 * 60 * 60 * 1000));
     var expires = "expires=" + d.toUTCString();
+    if (!cvalue) {
+        var expires = "expires=Thu, 01 Jan 1970 00:00:00 GMT";
+        cvalue = "";
+    }
     document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
 };
 var getCookie = function (name) {
@@ -726,17 +730,16 @@ var shared_methods = {
     buy_callback: function (data) {
         if (data.redirect) {
             if (data.cart_id) {
-                this.$root.cart_id = data.cart_id;
+                this.$root.set_cart_id(data.cart_id);
-                setCookie(this.$root.cookieName, data.cart_id, 30);
             }
             if (data.redirect.substr(0, 1) === '/') {
                 data.redirect = this.$root.target_url.replace(/^([^\/]+:\/\/[^\/]+)\/.*$/, "$1") + data.redirect;
             }
             var url = data.redirect;
             if (url.indexOf('?')) {
-                url = url + '&iframe=1&locale=' + lang + '&take_cart_id=' + this.$root.cart_id;
+                url = url + '&iframe=1&locale=' + lang + '&take_cart_id=' + encodeURIComponent(this.$root.get_cart_id());
             } else {
-                url = url + '?iframe=1&locale=' + lang + '&take_cart_id=' + this.$root.cart_id;
+                url = url + '?iframe=1&locale=' + lang + '&take_cart_id=' + encodeURIComponent(this.$root.get_cart_id());
             }
             url += this.$root.consent_parameter;
             if (this.$root.additionalURLParams) {
@@ -779,15 +782,24 @@ var shared_methods = {
         }
     },
     resume: function () {
+        if (!this.$root.get_cart_id() && this.$root.keep_cart) {
+            // create an empty cart whose id we can persist
+            this.$root.create_cart(this.resume)
+            return;
+        }
         var redirect_url;
         redirect_url = this.$root.target_url + 'w/' + widget_id + '/';
-        if (this.$root.subevent && !this.$root.cart_id) {
+        if (this.$root.subevent && this.$root.is_button && this.$root.items.length === 0) {
             // button with subevent but no items
             redirect_url += this.$root.subevent + '/';
         }
         redirect_url += '?iframe=1&locale=' + lang;
-        if (this.$root.cart_id) {
+        if (this.$root.get_cart_id()) {
-            redirect_url += '&take_cart_id=' + this.$root.cart_id;
+            redirect_url += '&take_cart_id=' + encodeURIComponent(this.$root.get_cart_id());
+            if (this.$root.keep_cart) {
+                // make sure the cart-id is used, even if the cart is currently empty
+                redirect_url += '&ajax=1'
+            }
         }
         if (this.$root.widget_data) {
             redirect_url += '&widget_data=' + encodeURIComponent(this.$root.widget_data_json);
@@ -1864,12 +1876,11 @@ var shared_root_methods = {
         if (this.$root.variation_filter) {
             url += '&variations=' + encodeURIComponent(this.$root.variation_filter);
         }
-        var cart_id = getCookie(this.cookieName);
         if (this.$root.voucher_code) {
             url += '&voucher=' + encodeURIComponent(this.$root.voucher_code);
         }
-        if (cart_id) {
+        if (this.$root.get_cart_id()) {
-            url += "&cart_id=" + encodeURIComponent(cart_id);
+            url += "&cart_id=" + encodeURIComponent(this.$root.get_cart_id());
         }
         if (this.$root.date !== null) {
             url += "&date=" + this.$root.date.substr(0, 7);
@@ -1939,7 +1950,6 @@ var shared_root_methods = {
                 root.display_add_to_cart = data.display_add_to_cart;
                 root.waiting_list_enabled = data.waiting_list_enabled;
                 root.show_variations_expanded = data.show_variations_expanded || !!root.variation_filter;
-                root.cart_id = cart_id;
                 root.cart_exists = data.cart_exists;
                 root.vouchers_exist = data.vouchers_exist;
                 root.has_seating_plan = data.has_seating_plan;
@@ -2004,8 +2014,8 @@ var shared_root_methods = {
         if (this.$root.voucher_code) {
             redirect_url += '&voucher=' + encodeURIComponent(this.$root.voucher_code);
         }
-        if (this.$root.cart_id) {
+        if (this.$root.get_cart_id()) {
-            redirect_url += '&take_cart_id=' + this.$root.cart_id;
+            redirect_url += '&take_cart_id=' + encodeURIComponent(this.$root.get_cart_id());
         }
         if (this.$root.widget_data) {
             redirect_url += '&widget_data=' + encodeURIComponent(this.$root.widget_data_json);
@@ -2027,7 +2037,28 @@ var shared_root_methods = {
         this.$root.subevent = event.subevent;
         this.$root.loading++;
         this.$root.reload();
-    }
+    },
+    create_cart: function(callback) {
+        var url = this.$root.target_url + 'w/' + widget_id + '/cart/create?ajax=1';
+
+        this.$root.overlay.frame_loading = true;
+        api._getJSON(url, (data) => {
+            this.$root.set_cart_id(data.cart_id);
+            this.$root.overlay.frame_loading = false;
+            callback()
+        }, () => {
+            this.$root.overlay.error_message = strings['cart_error'];
+            this.$root.overlay.frame_loading = false;
+        })
+    },
+    get_cart_id: function() {
+        if (this.$root.keep_cart) {
+            return getCookie(this.$root.cookieName);
+        }
+    },
+    set_cart_id: function(newValue) {
+        setCookie(this.$root.cookieName, newValue, 30);
+    },
 };
 
 var shared_root_computed = {
@@ -2049,9 +2080,8 @@ var shared_root_computed = {
     },
     voucherFormTarget: function () {
         var form_target = this.target_url + 'w/' + widget_id + '/redeem?iframe=1&locale=' + lang;
-        var cookie = getCookie(this.cookieName);
+        if (this.get_cart_id()) {
-        if (cookie) {
+            form_target += "&take_cart_id=" + encodeURIComponent(this.get_cart_id());
-            form_target += "&take_cart_id=" + cookie;
         }
         if (this.subevent) {
             form_target += "&subevent=" + this.subevent;
@@ -2091,9 +2121,8 @@ var shared_root_computed = {
             checkout_url += '?' + this.$root.additionalURLParams;
         }
         var form_target = this.target_url + 'w/' + widget_id + '/cart/add?iframe=1&next=' + encodeURIComponent(checkout_url);
-        var cookie = getCookie(this.cookieName);
+        if (this.get_cart_id()) {
-        if (cookie) {
+            form_target += "&take_cart_id=" + encodeURIComponent(this.get_cart_id());
-            form_target += "&take_cart_id=" + cookie;
         }
         form_target += this.$root.consent_parameter
         return form_target
@@ -2329,6 +2358,7 @@ var create_widget = function (element, html_id=null) {
                 has_seating_plan: false,
                 has_seating_plan_waitinglist: false,
                 meta_filter_fields: [],
+                keep_cart: true,
             }
         },
         created: function () {
@@ -2366,6 +2396,7 @@ var create_button = function (element, html_id=null) {
     var raw_items = element.attributes.items ? element.attributes.items.value : "";
     var skip_ssl = element.attributes["skip-ssl-check"] ? true : false;
     var disable_iframe = element.attributes["disable-iframe"] ? true : false;
+    var keep_cart = element.attributes["keep-cart"] ? true : false;
     var button_text = element.innerHTML;
     var widget_data = JSON.parse(JSON.stringify(window.PretixWidget.widget_data));
     for (var i = 0; i < element.attributes.length; i++) {
@@ -2417,7 +2448,8 @@ var create_button = function (element, html_id=null) {
                 widget_data: widget_data,
                 widget_id: 'pretix-widget-' + widget_id,
                 html_id: html_id,
-                button_text: button_text
+                button_text: button_text,
+                keep_cart: keep_cart || items.length > 0,
             }
         },
         created: function () {
@@ -2426,7 +2458,7 @@ var create_button = function (element, html_id=null) {
             observer.observe(this.$el, observerOptions);
         },
         computed: shared_root_computed,
-        methods: shared_root_methods
+        methods: shared_root_methods,
     });
     create_overlay(app);
     return app;
@@ -2492,13 +2524,14 @@ window.PretixWidget.open = function (target_url, voucher, subevent, items, widge
                 frame_dismissed: false,
                 widget_data: all_widget_data,
                 widget_id: 'pretix-widget-' + widget_id,
-                button_text: ""
+                button_text: "",
+                keep_cart: true
             }
         },
         created: function () {
         },
         computed: shared_root_computed,
-        methods: shared_root_methods
+        methods: shared_root_methods,
     });
     create_overlay(app);
     app.$nextTick(function () {