title | type | order |
---|---|---|
Form Input Bindings |
guide |
10 |
You can use the v-model
directive to create two-way data bindings on form input, textarea, and select elements. It automatically picks the correct way to update the element based on the input type. Although a bit magical, v-model
is essentially syntax sugar for updating data on user input events, plus special care for some edge cases.
`v-model` will ignore the initial `value`, `checked` or `selected` attributes found on any form elements. It will always treat the Vue instance data as the source of truth. You should declare the initial value on the JavaScript side, inside the `data` option of your component.
v-model
internally uses different properties and emits different events for different input elements:
- text and textarea elements use
value
property andinput
event; - checkboxes and radiobuttons use
checked
property andchange
event; - select fields use
value
as a prop andchange
as an event.
For languages that require an [IME](https://en.wikipedia.org/wiki/Input_method) (Chinese, Japanese, Korean etc.), you'll notice that `v-model` doesn't get updated during IME composition. If you want to cater for these updates as well, use `input` event instead.
<input v-model="message" placeholder="edit me">
<p>Message is: {{ message }}</p>
{% raw %}
Message is: {{ message }}
<span>Multiline message is:</span>
<p style="white-space: pre-line;">{{ message }}</p>
<br>
<textarea v-model="message" placeholder="add multiple lines"></textarea>
{% raw %}
{{ message }}
<textarea v-model="message" placeholder="add multiple lines"></textarea>
{% raw %}
Interpolation on textareas (<textarea>{{text}}</textarea>
) won't work. Use v-model
instead.
Single checkbox, boolean value:
<input type="checkbox" id="checkbox" v-model="checked">
<label for="checkbox">{{ checked }}</label>
{% raw %}
Multiple checkboxes, bound to the same Array:
<div id='example-3'>
<input type="checkbox" id="jack" value="Jack" v-model="checkedNames">
<label for="jack">Jack</label>
<input type="checkbox" id="john" value="John" v-model="checkedNames">
<label for="john">John</label>
<input type="checkbox" id="mike" value="Mike" v-model="checkedNames">
<label for="mike">Mike</label>
<br>
<span>Checked names: {{ checkedNames }}</span>
</div>
new Vue({
el: '#example-3',
data: {
checkedNames: []
}
})
{% raw %}
Checked names: {{ checkedNames }}
<input type="radio" id="one" value="One" v-model="picked">
<label for="one">One</label>
<br>
<input type="radio" id="two" value="Two" v-model="picked">
<label for="two">Two</label>
<br>
<span>Picked: {{ picked }}</span>
{% raw %}
Two
Picked: {{ picked }}
Single select:
<select v-model="selected">
<option disabled value="">Please select one</option>
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<span>Selected: {{ selected }}</span>
new Vue({
el: '...',
data: {
selected: ''
}
})
{% raw %}
If the initial value of your `v-model` expression does not match any of the options, the `` element will render in an "unselected" state. On iOS this will cause the user not being able to select the first item because iOS does not fire a change event in this case. It is therefore recommended to provide a disabled option with an empty value, as demonstrated in the example above.
Multiple select (bound to Array):
<select v-model="selected" multiple>
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<br>
<span>Selected: {{ selected }}</span>
{% raw %}
A
B
C
Selected: {{ selected }}
<script>
new Vue({
el: '#example-6',
data: {
selected: []
}
})
</script>
{% endraw %}
Dynamic options rendered with v-for
:
<select v-model="selected">
<option v-for="option in options" v-bind:value="option.value">
{{ option.text }}
</option>
</select>
<span>Selected: {{ selected }}</span>
new Vue({
el: '...',
data: {
selected: 'A',
options: [
{ text: 'One', value: 'A' },
{ text: 'Two', value: 'B' },
{ text: 'Three', value: 'C' }
]
}
})
{% raw %}
For radio, checkbox and select options, the v-model
binding values are usually static strings (or booleans for checkbox):
<!-- `picked` is a string "a" when checked -->
<input type="radio" v-model="picked" value="a">
<!-- `toggle` is either true or false -->
<input type="checkbox" v-model="toggle">
<!-- `selected` is a string "abc" when the first option is selected -->
<select v-model="selected">
<option value="abc">ABC</option>
</select>
But sometimes we may want to bind the value to a dynamic property on the Vue instance. We can use v-bind
to achieve that. In addition, using v-bind
allows us to bind the input value to non-string values.
<input
type="checkbox"
v-model="toggle"
true-value="yes"
false-value="no"
>
// when checked:
vm.toggle === 'yes'
// when unchecked:
vm.toggle === 'no'
The `true-value` and `false-value` attributes don't affect the input's `value` attribute, because browsers don't include unchecked boxes in form submissions. To guarantee that one of two values is submitted in a form (e.g. "yes" or "no"), use radio inputs instead.
<input type="radio" v-model="pick" v-bind:value="a">
// when checked:
vm.pick === vm.a
<select v-model="selected">
<!-- inline object literal -->
<option v-bind:value="{ number: 123 }">123</option>
</select>
// when selected:
typeof vm.selected // => 'object'
vm.selected.number // => 123
By default, v-model
syncs the input with the data after each input
event (with the exception of IME composition as stated above). You can add the lazy
modifier to instead sync after change
events:
<!-- synced after "change" instead of "input" -->
<input v-model.lazy="msg">
If you want user input to be automatically typecast as a number, you can add the number
modifier to your v-model
managed inputs:
<input v-model.number="age" type="number">
This is often useful, because even with type="number"
, the value of HTML input elements always returns a string. If the value cannot be parsed with parseFloat()
, then the original value is returned.
If you want whitespace from user input to be trimmed automatically, you can add the trim
modifier to your v-model
-managed inputs:
<input v-model.trim="msg">
If you're not yet familiar with Vue's components, you can skip this for now.
HTML's built-in input types won't always meet your needs. Fortunately, Vue components allow you to build reusable inputs with completely customized behavior. These inputs even work with v-model
! To learn more, read about custom inputs in the Components guide.