fix: keep only first user for default value on converting single

packages/nc-gui/components/smartsheet/column/DefaultValue.vue

@@ -34,6 +34,13 @@ const updateCdfValue = (cdf: string | null) => {
 onMounted(() => {
   updateCdfValue(vModel.value?.cdf ? vModel.value.cdf : null)
 })
+
+watch(
+  () => vModel.value.cdf,
+  (newValue) => {
+    cdfValue.value = newValue
+  },
+)
 </script>
 
 <template>

packages/nc-gui/components/smartsheet/column/UserOptions.vue

@@ -32,12 +32,19 @@ vModel.value.meta = {
 onMounted(() => {
   initialIsMulti.value = vModel.value.meta.is_multi
 })
+
+const updateIsMulti = (e) => {
+  vModel.value.meta.is_multi = e.target.checked
+  if (!vModel.value.meta.is_multi) {
+    vModel.value.cdf = vModel.value.cdf?.split(',')[0] || null
+  }
+}
 </script>
 
 <template>
   <div class="flex flex-col">
     <div>
-      <a-checkbox v-if="vModel.meta" v-model:checked="vModel.meta.is_multi" class="ml-1 mb-1">
+      <a-checkbox v-if="vModel.meta" :checked="vModel.meta.is_multi" class="ml-1 mb-1" @change="updateIsMulti">
         <span class="text-[10px] text-gray-600">Allow adding multiple users</span>
       </a-checkbox>
     </div>