[FIX] website_event: unblock button when no reserve

The website_event_questions override EventRegistrationForm's method
on_click and expects the returns is a deferred.

This commit provides a deferred in all instances avoiding an error.

Also what was done in e9454e79 and enables back the Register Now
button if no ticket was selected.

opw-1850527

In 11.0, this change e9454e79 solved the use case of:

- opening the registration of a ticket
- discard

=> the page must be reloaded to register a ticket

A new report is that since 9.0, if we try to register 0 ticket we would
also have to reload the page.

This commit backports e9454e79 and solves the 0 ticket registration.
Also if website_event_questions was installed there was an error
preventing an error message to be displayed.

saas-15 version of 9.0's #24966
opw-1851622
closes #24967

addons/website_event/i18n/website_event.pot

@@ -421,6 +421,13 @@ msgstr ""
 msgid "Photos of Past Events"
 msgstr ""
 
+#. module: website_event
+#. openerp-web
+#: code:addons/website_event/static/src/js/website_event.js:37
+#, python-format
+msgid "Please select at least one ticket."
+msgstr ""
+
 #. module: website_event
 #: model:ir.ui.view,arch_db:website_event.registration_template
 msgid "Price"

addons/website_event/static/src/js/website_event.js

@@ -1,9 +1,12 @@
 odoo.define('website_event.website_event', function (require) {
 
 var ajax = require('web.ajax');
+var core = require('web.core');
 var Widget = require('web.Widget');
 var web_editor_base = require('web_editor.base')
 
+var _t = core._t;
+
 // Catch registration form event, because of JS for attendee details
 var EventRegistrationForm = Widget.extend({
     start: function() {
@@ -13,7 +16,6 @@ var EventRegistrationForm = Widget.extend({
                 .off('click')
                 .removeClass('a-submit')
                 .click(function (ev) {
-                    $(this).attr('disabled', true);
                     self.on_click(ev);
                 });
         });
@@ -23,23 +25,28 @@ var EventRegistrationForm = Widget.extend({
         ev.preventDefault();
         ev.stopPropagation();
         var $form = $(ev.currentTarget).closest('form');
+        var $button = $(ev.currentTarget).closest('[type="submit"]');
         var post = {};
+        $('#registration_form table').siblings('.alert').remove();
         $("#registration_form select").each(function() {
             post[$(this).attr('name')] = $(this).val();
         });
         var tickets_ordered = _.some(_.map(post, function(value, key) { return parseInt(value) }));
         if (! tickets_ordered) {
-            return $('#registration_form table').after(
-                '<div class="alert alert-info">Please select at least one ticket.</div>'
-            );
+            $('<div class="alert alert-info"/>')
+                .text(_t('Please select at least one ticket.'))
+                .insertAfter('#registration_form table');
+            return $.Deferred();
         }
         else {
+            $button.attr('disabled', true);
             return ajax.jsonRpc($form.attr('action'), 'call', post).then(function (modal) {
                 var $modal = $(modal);
                 $modal.find('.modal-body > div').removeClass('container'); // retrocompatibility - REMOVE ME in master / saas-19
-                $modal.after($form).modal();
+                $modal.insertAfter($form).modal();
                 $modal.on('click', '.js_goto_event', function () {
                     $modal.modal('hide');
+                    $button.prop('disabled', false);
                 });
             });
         }