Changing an element's ID with Vue.js

Question

I have a form where the user select a number between 1 and 4 with a select tag, with the property of v-model="screens".

According to the number selected, with v-for="screen in screens" new select tags with options between 1 and 3 are showed to the user. For example if the user select 3, then 3 select tags are showed.

Then if in the second select the user select the number 3, three inputs are showed to the user also with v-for.

The problem is that I don't know how to change the id of the inputs so I can save the user info to the database.

Vue.component('select-square', {
    template:'#select-square',
    components:{
        'square-template' : {
            template: '#square-template'
        }
    }
});

new Vue({
    el: 'body',

    data: {
        screens:'',
    }
});

<script src="http://cdnjs.cloudflare.com/ajax/libs/vue/1.0.16/vue.min.js"></script>
<select class="form-control" v-model="screens" number>
    <option>1</option>
    <option>2</option>
    <option>3</option>
</select>

<div v-for="screen in screens">
    <select-square></select-square>
</div>

<template id="select-square">
    <select class="form-control" v-model="squares" number>
        <option>1</option>
        <option>2</option>
        <option>3</option>
    </select>
    <square-template v-for="square in squares"></square-template>
</template>

<template id="square-template">
    <input>
</template>

Answer 1

Ok. I already figure it out. v-bind="{id: square}" make the trick

Vue.component('select-square', {
    template:'#select-square',

    data: function (){
        return {squares:''}
    },

    components:{
        'square-template' : {
            template: '#square-template'
        }
    }
});

new Vue({
    el: 'body',

    data: {
        screens:'',
    }
});

<script src="http://cdnjs.cloudflare.com/ajax/libs/vue/1.0.16/vue.min.js"></script>

<select class="form-control" v-model="screens" number>
    <option>1</option>
    <option>2</option>
    <option>3</option>
</select>

<div v-for="screen in screens">
    <select-square></select-square>
</div>

<template id="select-square">
    <select class="form-control" v-model="squares" number>
        <option>1</option>
        <option>2</option>
        <option>3</option>
    </select>
    <square-template v-bind="{id: square}" v-for="square in squares"></square-template>
</template>

<template id="square-template">
    <input>
</template>

Answer 2

Well, in your ready method you can watch for the screens changes like

data: function(){

  return {

    screens: 0,

    newSelectScreens: 0

  }

},

ready: function(){

    this.$watch('screens', function(){

    this.newSelectScreens = this.screens;

  });

}

Then for the new select screens

<select v-for="n in newSelectScreens">
  <options></options>
</select>