vue-form

Form validation for Vue.js 2.2+

Install

Available through npm as vue-form.

import VueForm from 'vue-form';
// or var VueForm = require('vue-form') or window.VueForm if you are linking directly to the dist file
 
// install globally
Vue.use(VueForm);
Vue.use(VueForm, options);
 
// or use the mixin
...
mixins: [VueForm]
...
mixins: [new VueForm(options)]
...

Usage

Once installed you have access to four components (vue-form, validate, field, field-messages) for managing form state, validating form fields and displaying validation messages.

Live examples

• Configured to work with Bootstrap styles: https://jsfiddle.net/fergal_doyle/zfqt4yhq/
• Matching passwords and password strength: https://jsfiddle.net/fergal_doyle/9rn5kLkw/
• Field error messages based on submitted state (labels tied to inputs with auto-label): https://jsfiddle.net/fergal_doyle/bqys2p5y/

Example

<div id="app">
  <vue-form :state="formstate" @submit.prevent="onSubmit">
 
    <validate tag="label">
      <span>Name *</span>
      <input v-model="model.name" required name="name" />
 
      <field-messages name="name">
        <div>Success!</div>
        <div slot="required">Name is a required field</div>
      </field-messages>
    </validate>
 
    <validate tag="label">
      <span>Email</span>
      <input v-model="model.email" name="email" type="email" required />
 
      <field-messages name="email">
        <div slot="required">Email is a required field</div>
        <div slot="email">Email is not valid</div>
      </field-messages>
    </validate>
 
    <button type="submit">Submit</button>
  </vue-form>
  <pre>{{ formstate }}</pre>
</div>

Vue.use(VueForm);
 
new Vue({
  el: '#app',
  data: {
    formstate: {},
    model: {
      name: '',
      email: 'invalid-email'
    }
  },
  methods: {
    onSubmit: function () {
      if(this.formstate.$invalid) {
        // alert user and exit early
        return;
      }
      // otherwise submit form
    }
  }
});

The output of formstate will be:

{
  "$dirty": false,
  "$pristine": true,
  "$valid": false,
  "$invalid": true,
  "$submitted": false,
  "$touched": false,
  "$untouched": true,
  "$focused": false,
  "$pending": false,
  "$error": {
    // fields with errors are copied into this object
  },
  "$submittedState": {
    // each form sumbit, state is cloned into this object
  },
  "name": {
    "$name": "name",
    "$dirty": false,
    "$pristine": true,
    "$valid": false,
    "$invalid": true,
    "$touched": false,
    "$untouched": true,
    "$focused": false,
    "$pending": false,
    "$error": {
      "required": true
    }
  },
  "email": {
    "$name": "email",
    "$dirty": false,
    "$pristine": true,
    "$valid": false,
    "$invalid": true,
    "$touched": false,
    "$untouched": true,
    "$focused": false,
    "$pending": false,
    "$error": {
      "email": true
    }
  }
}

Displaying messages

Display validation errors or success messages with field-messages.

The show prop supports simple expressions which specifiy when messages should be displayed based on the current state of the field, e.g: $dirty, $dirty && $touched, $dirty || $touched, $touched || $submitted, $focused && ($dirty || $submitted)

<field-messages name="name" show="$dirty && $touched">
  <div slot="errorKeyA">Error message A</div>
  <div slot="errorKeyB">Error message B</div>
</field-messages>

Or use scoped templates:

<field-messages name="fieldName">
  <span>Success</span>
  <template slot="required" scope="state">
    <span v-if="state.$touched || state.$submitted">Name is a required field</span>
  </template>
  <template slot="errorKeyB" scope="state">
    <span v-if="state.$touched || state.$dirty">Error message B</span>
  </template>
</field-messages>

Validators

type="email"
type="url"
type="number"
required
minlength
maxlength
pattern
min (for type="number")
max (for type="number")

You can use static validation attributes or bindings. If it is a binding, the input will be re-validated every binding update meaning you can have inputs which are conditionally required etc.

<!-- static validators -->
<validate>
  <input type="email" name="email" v-model="model.email" required />
</validate>
<validate>
  <input type="text" name="name" v-model="model.name" maxlength="25" minlength="5" />
</validate>
 
<!-- bound validators -->
<validate>
  <input type="email" name="email" v-model="model.email" :required="isRequired" />
</validate>
<validate>
  <input type="text" name="name" v-model="model.name" :maxlength="maxLen" :minlength="minLen" />
</validate>

Custom validators

You can register global and local custom validators.

Global custom validator

 
var options = {
  validators: {
    'my-custom-validator': function (value, attrValue, vnode) {
      // return true to set input as $valid, false to set as $invalid
      return value === 'custom';
    }
  }
}
 
Vue.use(VueForm, options);
// or
// mixins: [new VueForm(options)]

<validate>
  <input v-model="something" name="something" my-custom-validator />
  <!--
    slot name inside field-messages would be: <div slot="my-custom-validator">...</div>
  -->
</validate>

Local custom validator

// ...
methods: {
  customValidator: function (value) {
    // return true to set input as $valid, false to set as $invalid
    return value === 'custom';
  }
},
// local custom validator can also be a data or computed property
computed: {
  isEmailAvailable: function () {
    // return true to set input as $valid, false to set as $invalid
  }
}
// ...

<validate :custom="{customValidator: customValidator, 'email-available': isEmailAvailable}">
  <input v-model="something" name="something" />
  <!--
    slot name inside field-messages would be: <div slot="customValidator">...</div>
  -->
</validate>

Async validators:

Async validators are custom validators which return a Promise. resolve() true or false to set field validity.

// ...
methods: {
  customValidator (value) {
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        resolve(value === 'ajax');
      }, 100);
    });
  }
}
// ...

Async validator with debounce (example uses lodash debounce)

methods: {
  debounced: _.debounce(function (value, resolve, reject) {
    fetch('https://httpbin.org/get').then(function(response){
      resolve(response.isValid);
    });
  }, 500),
  customValidator (value) {
    return new Promise((resolve, reject) => {
      this.debounced(value, resolve, reject);
    });
  }
}

Reset state

<vue-form ref="form" :state="formstate">

resetState: function () {
  this.formstate._reset();
  // or
  this.$refs.form.reset();
}

State classes

As form and input validation states change, state classes are added and removed

Possible form classes:

vf-form-dirty, vf-form-pristine, vf-form-valid, vf-form-invalid, vf-form-submitted, vf-form-focused- vf-form-pending

Possible input classes:

vf-dirty, vf-pristine, vf-valid, vf-invalid, vf-focused, vf-pending

// also for every validation error, a class will be added, e.g.
vf-invalid-required, vf-invalid-minlength, vf-invalid-max, etc

Input wrappers (e.g. the tag the validate component renders) will also get state classes, but with the field prefix, e.g.

vf-field-dirty, vf-field-pristine, vf-field-valid, vf-field-invalid, vf-field-focused, vf-field-pending

Custom components

When writing custom form field components, e.g. <my-checkbox v-model="foo"></my-checkbox> you should trigger the focus and blur events after user interaction either by triggering native dom events on the root node of your component, or emitting Vue events (this.$emit('focus)) so the validate component can detect and set the $dirty and $touched states on the field.

Component props

vue-form

• state Object on which form state is set
• tag String, defaults to form
• show-messages String, applies to all child field-messages, show errors dependant on form field state e.g. $touched, $dirty || $touched, '$touched || $submitted'

validate

• state Optional way of passing in the form state. If omitted form state will be found in the $parent
• custom Object containing one or many custom validators. {validatorName: validatorFunction}
• tag String which specifies what element tag should be rendered by the validate component, defaults to span
• auto-label: Boolean, defaults to false. Automatically set for and id attributes of label and input elements found inside the validate component
• debounce Number, defaults to none, which specifies the delay (milliseconds) before validation takes place.

field-messages

• state Optional way of passing in the form state. If omitted form state will be found in the $parent
• name String which specifies the related field name
• tag String, defaults to div
• show String, show error dependant on form field state e.g. $touched, $dirty || $touched, '$touched || $submitted'
• auto-label Boolean, defaults to false. Automatically set the for attribute of labels found inside the field-messages component

field

• tag String, defaults to div
• auto-label Boolean, defaults to true. Automatically set for and id attributes of label and input elements found inside the validate component

Config

Set config options when using Vue.use(VueForm, options), or when using a mixin mixins: [new VueForm(options)] defaults:

{
    validators: {},
    formComponent: 'vueForm',
    formTag: 'form',
    messagesComponent: 'fieldMessages',
    messagesTag: 'div',
    showMessages: '',
    validateComponent: 'validate',
    validateTag: 'div',
    fieldComponent: 'field',
    fieldTag: 'div',
    formClasses: {
      dirty: 'vf-form-dirty',
      pristine: 'vf-form-pristine',
      valid: 'vf-form-valid',
      invalid: 'vf-form-invalid',
      touched: 'vf-form-touched',
      untouched: 'vf-form-untouched',
      focused: 'vf-form-focused',
      submitted: 'vf-form-submitted',
      pending: 'vf-form-pending'
    },
    validateClasses: {
      dirty: 'vf-field-dirty',
      pristine: 'vf-field-pristine',
      valid: 'vf-field-valid',
      invalid: 'vf-field-invalid',
      touched: 'vf-field-touched',
      untouched: 'vf-field-untouched',
      focused: 'vf-field-focused',
      submitted: 'vf-field-submitted',
      pending: 'vf-field-pending'
    },
    inputClasses: {
      dirty: 'vf-dirty',
      pristine: 'vf-pristine',
      valid: 'vf-valid',
      invalid: 'vf-invalid',
      touched: 'vf-touched',
      untouched: 'vf-untouched',
      focused: 'vf-focused',
      submitted: 'vf-submitted',
      pending: 'vf-pending'
    },
    Promise: typeof Promise === 'function' ? Promise : null
}