Check-in rule editor: Fix reactivity issue in select2 component

src/pretix/static/pretixcontrol/js/ui/checkinrules/lookup-select2.vue

@@ -10,9 +10,14 @@
         '        <slot></slot>\n' +
         '      </select>'),
     mounted: function () {
+      this.build();
+    },
+    methods: {
+      build: function () {
         var vm = this;
         var multiple = this.multiple;
         $(this.$el)
+            .empty()
             .select2(this.opts())
             .val(this.value || "")
             .trigger("change")
@@ -28,7 +33,6 @@
         }
         $(vm.$el).trigger("change");
       },
-    methods: {
       opts: function () {
         return {
           theme: "bootstrap",
@@ -60,17 +64,29 @@
     },
     watch: {
       placeholder: function (val) {
-        $(this.$el).empty().select2(this.opts());
+        $(this.$el).select2("destroy");
         this.build();
       },
       required: function (val) {
-        $(this.$el).empty().select2(this.opts());
+        $(this.$el).select2("destroy");
         this.build();
       },
       url: function (val) {
-        $(this.$el).empty().select2(this.opts());
+        $(this.$el).select2("destroy");
         this.build();
       },
+      value: function (newval, oldval) {
+        if (JSON.stringify(newval) !== JSON.stringify(oldval)) {
+          $(this.$el).empty();
+          if (newval) {
+            for (var i = 0; i < newval["objectList"].length; i++) {
+              var option = new Option(newval["objectList"][i]["lookup"][2], newval["objectList"][i]["lookup"][1], true, true);
+              $(this.$el).append(option);
+            }
+          }
+          $(this.$el).trigger("change");
+        }
+      },
     },
     destroyed: function () {
       $(this.$el)