In use vee-validate library vue-select element does not work - validation

Question

In vuejs 2.5 application I use vee-validate library ( http://vee-validate.logaretm.com/examples.html ) with inputs like:
<template>
<section>
<form #submit.prevent="validateBeforeSubmit" class="form-horizontal">
<div class="row">
<div class="col-xs-12 form-group">
<label class="col-xs-12 col-sm-4 control-label" for="name">Name<span class="required"> * </span></label>
<div class="col-xs-12 col-sm-8">
<input v-validate="'required|max:255'" v-model="task.name"
:class="{ 'form-control':true, 'input': true, 'text-danger': vueErrorsList.has('name') }" name="name" id="name"
type="text" placeholder="name">
<span v-show="vueErrorsList.has('name')" class="text-danger">{{ vueErrorsList.first('name') }}</span>
</div>
</div>
</div>
<div class="row">
<div class="col-xs-12 form-group">
<label class="col-xs-12 col-sm-4 control-label" for="category_id">Category<span class="required"> * </span></label>
<div class="col-xs-12 col-sm-8">
<v-select v-validate="'required'" id="category_id" name="category_id" v-model="selection_category_id" :options=categoriesSelectionList></v-select>
<span v-show="vueErrorsList.has('category_id')" class="text-danger">{{ vueErrorsList.first('category_id') }}</span>
</div>
</div>
</div>
</form>
</section>
</template>
<script>
import {bus} from '../../app';
...
import vSelect from 'vue-select'
Vue.component('v-select', vSelect) // https://github.com/sagalbot/vue-select
import moment from 'moment';
...
export default {
created() {
this.$validator.localize(window.CURRENT_LANG, {
attributes: {
selection_category_id: 'category',
category_id: 'category',
...
}
});
}, // created() {
...
methods
:
{
validateBeforeSubmit()
{
this.$validator.validateAll().then((result) => {
if (result) {
this.updateTask()
} else {
this.showPopupMessage('Error ' + ( this.is_insert ? 'adding' : 'updating' ) + ' task. ', 'error');
}
})
}
, // validateBeforeSubmit() {
updateTask()
{
...
}
, // updateTask() {
} // methods:{
}
</script>
But In the code above the second input is vue-select element ( https://github.com/sagalbot/vue-select )
and it is not validated at all.
I put
v-validate="'required'"
to it but it does not work.
I use validateBeforeSubmit method and if there is a way to make some kind of custom validation, so I would check is value in
select input is selected?
Thank you!