How to make vue JS 3 vue-next-select component as required

I want to make it required select list

     <vue-select  v-on:change="form.inputno = $event.target.value" v-model="form.input[index]" :options="trains" clear-on-select searchable close-on-select label-by="inputno" class="text-left h-10 sinput" search-placeholder="Search Input No" placeholder="Input No"  track-by="inputno"></vue-select>