How to correctly write v-model for a multidimensional array of data in a form?

Question

Vue.js

I confess, I gave up, I'll try to find advice here.

I am rewriting the forms of the old site from php to vue. Work Schedule Module.

<div v-for="(city,index) in cities">
       <schedule
          :item="city"
          @form-saved="saveData">
      </schedule>
   </div>

in the form itself my trash begins (the habit of working with php and arrays .. in the old form it was like this.

<?php foreach ($data['days'] as $key=>$day): ?>
            <label> <?php echo $day['rus']; ?>
            </label>
            <input type="text" name="<?php echo $day['eng'];?>[open]" value="" class="time_input">---
            <input type="text" name="<?php echo $day['eng'];?>[close]" value="" class="time_input"><span class="extra">примечание</span>
            <input type="text" name="<?php echo $day['eng'];?>[extra]" value=""><?php endforeach; ?>

and then I sort of serialized it all through jquery.

Now I'm trying this way and that to form a more or less required array, but I can't manage to bind three fields to the day of the week and then to the city.

<div v-for="(day,index) in days" :key="day.engname">
                <label class="block bg-academy text-white"> {{day.rus}} </label>
                    <input type="text" v-model="city.open[index]"  class="time_input">---
                    <input type="text" v-model="city.close[index]" class="time_input"><span class="extra">примечание</span>
                    <input type="text" v-model="city.extra[index]" >
               </div>

v-model="city.close[index]" I already tried to bind in days. And so and so, but I just don’t understand apparently (

city:{
            id:this.item.id,
            open:[], //вот как сюда прикрутить дни недели?(
            close:[],
            extra:[]
        },

        days:[
            {rus:'Понедельник',
            engname:'monday',
            open:'', // это я привязывал к дням через v-model="days[index].open" но сюда никак город
            close:'',
            extra:''
            },
            {rus:'Вторник',
            engname:'tuesday',
             open:'',
            close:'',
            extra:''
            }
        ],

Now on an output such data I receive from the form.

"id": 1,
  "open": [
    "12-00", //это время понедельника
    "12-30" //это время вторника
  ],
  "close": [
    "21-30",
    "22-00"
  ],

but I would like
id:1
monday: {
open: ...,
close:...,
}.
I can’t master these complex forms in any way (advise, please.