Fix addressform handling reloading address-info while XHR-request is still running (Z#23210723) (#5558)

* Fix handling answers with null-value

* fix handling re-requesting the same url while XHR is still running

src/pretix/static/pretixbase/js/addressform.js

@@ -95,10 +95,6 @@ $(function () {
         }
 
         const update = function (ev) {
-            if (xhr) {
-                xhr.abort();
-            }
-
             dependents.state.prop("data-selected-value", dependents.state.val());
             if (dependents.transmission_type) {
                 dependents.transmission_type.prop("data-selected-value", dependents.transmission_type.val());
@@ -119,17 +115,24 @@ $(function () {
                 url.searchParams.append("transmission_type_required", !dependents.transmission_type.find("option[value='-']").length);
             }
 
+            if (xhr && url in responseCache) {
+                if (responseCache[url] == xhr) {
+                    // already requested this, but XHR is still running and will resolve promise
+                    // only re-resolve promise for JSON-data in responseCache[url]
+                    return;
+                } else {
+                    // abort current xhr as it is not the one we want
+                    // aborting deletes responseCache[url] but async
+                    xhr.abort();
+                }
+            }
+
             if (!(url in responseCache)) {
-                responseCache[url] = new Promise((resolve, reject) => {
+                responseCache[url] = xhr = $.ajax({
-                    xhr = $.ajax({
+                    dataType: "json",
-                        dataType: "json",
+                    url: url,
-                        url: url,
+                    timeout: 3000,
-                        timeout: 3000,
+                });
-                        success: resolve,
-                    }).fail(function(){
-                        reject();
-                    });
-                })
             }
 
             Promise.resolve(responseCache[url]).then(function (data) {

src/pretix/static/pretixpresale/js/ui/questions.js

@@ -168,7 +168,7 @@ function questions_init_profiles(el) {
         for (var p of profiles) {
             data = {};
             for (var key of Object.keys(p)) {
-                if (key.startsWith("_")) {
+                if (key.startsWith("_") || p[key] === null) {
                     continue;
                 }
                 matched_field = getMatchingInput(key, p[key], scope);
@@ -230,6 +230,7 @@ function questions_init_profiles(el) {
         // _0 and _1 are e.g. for phone-fields. name-fields have their parts/keys already split
         var $fields = $('[name$="' + key + '"], [name$="' + key + '_0"], [name$="' + key + '_1"]', scope).not(":disabled");
         if ($fields.length) return $fields;
+        if (!answer) return null;
 
         if (answer.identifier) {
             $label = $('[data-identifier="' + answer.identifier + '"]', scope);