Resolving Error Issues

You may have mistakenly connected properties to nothingness. This is evident with the use of :required in

<select class="form-control" v-model="selected" :required @change="changeLocation">

and :selected in

<option :selected>Choose Province</option>

To rectify this issue, revise your code as follows:

<template>
  <select class="form-control" v-model="selected" :required @change="changeLocation">
    <option>Choose Province</option>
    <option v-for="option in options" v-bind:value="option.id" >{{ option.name }}</option>
 </select>
</template>

Setting Default Values for Select Tags

1. In order for v-model to function correctly, you must create a data property named selected. Do so by implementing:

   {
     data () {
       return {
         selected: "Choose Province"
       }
     }
   }
   

2. If the above method seems complex, an alternate approach involves:

   <template>
     <select class="form-control" :required="true" @change="changeLocation">
      <option :selected="true">Choose Province</option>
      <option v-for="option in options" v-bind:value="option.id" >{{ option.name }}</option>
     </select>
   </template>
   

Determining the Suitable Methodology

1. Utilize the v-model method if your default value is dependent on a data property.

2. Select the second method if your initial selection should be the first option.

3. For programmatic control, opt for the following technique:

   <select class="form-control" :required="true">
     <option 
      v-for="option in options" 
      v-bind:value="option.id"
      :selected="option == '<the default value you want>'"
     >{{ option }}</option>
   </select>
   

To simplify things, you can choose to either set the selected option as true or false.

<option :selected="selectedDay === 1" value="1">1</option>

In this scenario, the data object looks like:

data() {
    return {
        selectedDay: '1',
        // [1, 2, 3, ..., 31]
        days: Array.from({ length: 31 }, (v, i) => i).slice(1)
    }
}

This snippet demonstrates setting the selected month day:

<select v-model="selectedDay" style="width:10%;">
    <option v-for="day in days" :selected="selectedDay === day">{{ day }}</option>
</select>

Within your dataset:

{
    data() {
        selectedDay: 1,
        // [1, 2, 3, ..., 31]
        days: Array.from({ length: 31 }, (v, i) => i).slice(1)
    },
    mounted () {
        let selectedDay = new Date();
        this.selectedDay = selectedDay.getDate(); // Updates selectedDay to today's date
    }
}

<select v-model="challan.warehouse_id">
<option value="">Select Warehouse</option>
<option v-for="warehouse in warehouses" v-bind:value="warehouse.id"  >
   {{ warehouse.name }}
</option>

You can assign the value of "challan.warehouse_id" from the data retrieved from the API call to edit a challan:

editChallan: function() {
    let that = this;
    axios.post('/api/challan_list/get_challan_data', {
    challan_id: that.challan_id
 })
 .then(function (response) {
    that.challan = response.data;
 })
 .catch(function (error) {
    that.errors = error;
  }); 
 }

To fix the issue, you just have to eliminate v-bind (:) from selected and required attributes. Here's how you should modify it:

<template>
    <select class="form-control" v-model="selected" required @change="changeLocation">
        <option selected>Choose Province</option>
        <option v-for="option in options" :value="option.id" >{{ option.name }}</option>
    </select>
</template>

The reason for the error is that these attributes are not actually binding anything to the Vue instance.

Here is my code snippet for implementing reactive multiselect functionality:

data() {
    return {
        article: {title: 'aaaaa', 'categoriesIds': [1,3], ...},
        selectCategories: {1: 'xxx', 2: 'www', 3: 'yyy', 4: 'zzz'},
    }
},

This is the template section where the multiselect feature is defined:

<div class="form-group">
     <label for="content">Categories</label>
     <select name="categories" 
         v-model="article.categoriesIds" 
         id="categories" 
         multiple 
         class="form-control col-md-5" 
         size="6">
         <option v-for="(category, key) in selectCategories" 
             :key="key" 
             v-bind:value="key">{{category}}</option>
     </select>
</div>

The selected items from the multiselect are linked to the article.categoriesIds array.

One effective method that I frequently rely on is to incorporate a directive into your VueJS initialization in app.js or wherever you are setting up VueJS, for example:

Vue.directive('attr', (el, binding) => {
  if (binding.value === true) binding.value = ''
  if (binding.value === '' || binding.value) {
    el.setAttribute(binding.arg, binding.value)
  }
})

You can then use v-attr to define an attribute, for instance:

<option value="Western Australia" v-attr:selected="form.state == 'Western Australia'">Western Australia</option>

My understanding is that the primary objective here is to designate "Choose Province" as the default option. After experimenting with different approaches, I found that sticking to a simple solution yielded the best results for me:

<template>
    <select class="form-control" v-model="selected" :required @change="changeLocation">
        <option>Choose Province</option> # just an option with no pre-selected or assigned value
        <option v-for="option in options" v-bind:value="option.id" >{{ option.name }}</option>
    </select>
</template>  

To implement this, utilize the v-model attribute within the select tag and incorporate the useForm library from Vue. Set the default value of form.category to 'choose' or any other preferred default value.

<script setup>
import { Head, Link, useForm } from '@inertiajs/vue3';
const form = useForm({
    category: 'choose',
    file: null,
});
</script>

<template>

                    <div class="grid grid-cols-1 gap-5">
                        <label for="category" class="font-black">Choose A Category</label>
                        <select id="category" v-model="form.category" required >
                            <option value="choose" disabled>choose</option>
                            <option value="Other">other</option>
                        </select>
                        <div class="bg-red-200 rounded-lg p-2" v-if="form.errors.category">
                            {{ form.errors.category }}
                        </div>
                    </div>


</template>