v-model with checkboxes in Vue - Mini Project: Build & Apply

Using v-model with Checkboxes in Vue

📖 Scenario: You are building a simple preferences form for a website where users can select their favorite fruits using checkboxes.

🎯 Goal: Create a Vue component that uses v-model to bind an array of selected fruits to multiple checkboxes. The component should update the array automatically when checkboxes are checked or unchecked.

📋 What You'll Learn

Create a Vue component with a reactive array called selectedFruits initialized as empty.

Add a list of fruit names as checkboxes in the template.

Use v-model on each checkbox to bind it to selectedFruits.

Display the currently selected fruits below the checkboxes.

💡 Why This Matters

🌍 Real World

Checkbox groups are common in forms where users select multiple options, such as preferences, filters, or interests.

💼 Career

Understanding how to bind multiple checkboxes to a reactive array with v-model is essential for building interactive forms in Vue applications.

1

Set up the initial data array

Create a Vue component with a reactive array called selectedFruits initialized as an empty array [] inside the setup() function using ref.

Vue

// Create a reactive array called selectedFruits initialized as []
// Your code here



  

Hint

Use import { ref } from 'vue' and then const selectedFruits = ref([]) inside <script setup>.

2

Add a list of fruit checkboxes

In the <template>, add three checkboxes with labels: Apple, Banana, and Cherry. Use input elements of type checkbox with value attributes set to the fruit names.

Vue

import { ref } from 'vue'

const selectedFruits = ref([])



  
  

Hint

Use three input elements with type="checkbox" and value set to each fruit name.

3

Bind checkboxes with v-model

Add v-model="selectedFruits" to each checkbox input to bind them to the reactive array selectedFruits.

Vue

import { ref } from 'vue'

const selectedFruits = ref([])



  
  
     Apple
  
  
     Banana
  
  
     Cherry
  

Hint

Add v-model="selectedFruits" to each checkbox input to link them to the reactive array.

4

Display selected fruits

Below the checkboxes, add a <div> that shows the text Selected fruits: followed by the joined list of fruits in selectedFruits using {{ selectedFruits.join(', ') }}.

Vue

import { ref } from 'vue'

const selectedFruits = ref([])



  
     Apple
  
  
     Banana
  
  
     Cherry
  
  
    
    
  

Hint

Use {{ selectedFruits.join(', ') }} inside a <div> to display the selected fruits separated by commas.

Practice

1. What type of data should you use with v-model when binding to multiple checkboxes in Vue?

easy

A. A string representing the last selected checkbox

B. A boolean to represent true or false

C. An array to hold the selected values

D. A number counting how many checkboxes are checked

Solution

1. Step 1: Understand checkbox binding

   When multiple checkboxes are bound with v-model, Vue expects an array to store all selected values.

2. Step 2: Compare data types for checkboxes

   A boolean is used for single checkboxes, but for multiple checkboxes, an array collects all checked values.

3. Final Answer:

   An array to hold the selected values -> Option C

4. Quick Check:

   Multiple checkboxes = array [OK]

Hint: Multiple checkboxes always bind to an array [OK]

Common Mistakes:

• Using a boolean for multiple checkboxes
• Binding to a string instead of an array
• Expecting a number to track checked boxes

2. Which of the following is the correct syntax to bind a single checkbox with v-model in Vue?

easy

A. <input type='checkbox' v-model='checked' />

B. <input type='checkbox' :value='checked' />

C. <input type='checkbox' v-bind='checked' />

D. <input type='checkbox' v-model:value='checked' />

Solution

1. Step 1: Identify correct binding directive

   The v-model directive binds the checkbox's checked state to a data property.

2. Step 2: Check syntax correctness

   <input type='checkbox' v-model='checked' /> uses v-model='checked' which is the correct and simplest syntax for binding a single checkbox.

3. Final Answer:

   <input type='checkbox' v-model='checked' /> -> Option A

4. Quick Check:

   Single checkbox uses v-model='property' [OK]

Hint: Use v-model directly on checkbox for single binding [OK]

Common Mistakes:

• Using :value instead of v-model
• Using v-bind without specifying property
• Using v-model:value which is invalid

3. Given this Vue template code:

<template>
  <input type='checkbox' v-model='selected' value='apple' />
  <input type='checkbox' v-model='selected' value='banana' />
  <input type='checkbox' v-model='selected' value='cherry' />
  <p>Selected: {{ selected }}</p>
</template>

<script setup>
import { ref } from 'vue'
const selected = ref([])
</script>

What will be displayed after the user checks the boxes for "apple" and "cherry"?

medium

A. Selected: 'apple,cherry'

B. Selected: ['apple', 'cherry']

C. Selected: ['apple']

D. Selected: true

Solution

1. Step 1: Understand v-model with multiple checkboxes

   When multiple checkboxes share the same v-model bound to an array, Vue adds the checkbox's value to the array when checked.

2. Step 2: Check which boxes are selected

   User checked "apple" and "cherry", so the array contains ['apple', 'cherry'].

3. Final Answer:

   Selected: ['apple', 'cherry'] -> Option B

4. Quick Check:

   Checked boxes values collected in array [OK]

Hint: Multiple checkboxes with same v-model store values in array [OK]

Common Mistakes:

• Expecting a string instead of an array
• Thinking only last checked value is stored
• Confusing boolean with array for multiple checkboxes

4. What is wrong with this Vue checkbox binding?

<input type='checkbox' v-model='checked' value='yes' />

<script setup>
import { ref } from 'vue'
const checked = ref(false)
</script>

Why does checking the box not add 'yes' to checked?

medium

A. Because checked should be a string, not boolean

B. Because value attribute is missing

C. Because v-model cannot be used on checkboxes

D. Because checked is a boolean, not an array, so value is ignored

Solution

1. Step 1: Identify data type for v-model

   The variable checked is a boolean, so Vue treats the checkbox as a single toggle (true/false).

2. Step 2: Understand effect of value attribute

   When v-model is boolean, the value attribute is ignored; it only matters when binding to an array.

3. Final Answer:

   Because checked is a boolean, not an array, so value is ignored -> Option D

4. Quick Check:

   Boolean v-model ignores value attribute [OK]

Hint: Boolean v-model ignores value; use array for multiple values [OK]

Common Mistakes:

• Thinking value attribute always affects checkbox state
• Believing v-model can't be used on checkboxes
• Using string instead of boolean or array incorrectly

5. You want to create a group of checkboxes for selecting favorite fruits using v-model. The data property is favorites initialized as an empty array. Which code snippet correctly updates favorites when users check or uncheck fruits?

hard

A. <input type='checkbox' v-model='favorites' value='apple' />
<input type='checkbox' v-model='favorites' value='banana' />
<input type='checkbox' v-model='favorites' value='cherry' />

B. <input type='checkbox' v-model='favorites' :value='true' />
<input type='checkbox' v-model='favorites' :value='false' />

C. <input type='checkbox' v-model='favorites.apple' />
<input type='checkbox' v-model='favorites.banana' />

D. <input type='checkbox' v-model='favorites' value='true' />
<input type='checkbox' v-model='favorites' value='false' />

Solution

1. Step 1: Understand array binding for multiple checkboxes

   Binding multiple checkboxes to the same array with v-model and distinct value attributes collects checked values in the array.

2. Step 2: Evaluate each option's correctness

   <input type='checkbox' v-model='favorites' value='apple' /> <input type='checkbox' v-model='favorites' value='banana' /> <input type='checkbox' v-model='favorites' value='cherry' /> correctly uses v-model='favorites' with unique string values for each checkbox, so checked fruits are added or removed from the array.

3. Final Answer:

   <input type='checkbox' v-model='favorites' value='apple' /> <input type='checkbox' v-model='favorites' value='banana' /> <input type='checkbox' v-model='favorites' value='cherry' /> -> Option A

4. Quick Check:

   Multiple checkboxes + array + unique values = correct binding [OK]

Hint: Use array with unique values for multiple checkboxes [OK]

Common Mistakes:

• Using boolean values instead of unique strings
• Binding to object properties instead of array
• Using same value for all checkboxes