Validation

Vue Bootstrap 5 Validation

Provide valuable, actionable feedback to your users with Vue form validation, via browser default behaviors or custom styles and JavaScript.

Note: We currently recommend using custom validation styles, as native browser default validation messages are not consistently exposed to assistive technologies in all browsers (most notably, Chrome on desktop and mobile).

Basic example

For custom MDB form validation messages, you’ll need to add the novalidate boolean attribute to your <form>. This disables the browser default feedback tooltips, but still provides access to the form validation APIs in JavaScript. Try to submit the form below; our JavaScript will intercept the submit button and relay feedback to you. When attempting to submit, you’ll see the :invalid and :valid styles applied to your form controls.

Custom feedback styles apply custom colors, borders, focus styles, and background icons to better communicate feedback.

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How it works

Note: Our validation can be used together with packages specializing in form validation. Check out this tutorial to see how to painlessly integrate MDB Vue with VeeValidate.

Here’s how form validation works with MDB:

  • HTML form validation is applied via CSS’s two pseudo-classes, :invalid and :valid. It applies to <MDBInput> and <MDBTextarea> elements.
  • MDB scopes the :invalid and :valid styles to parent .was-validated class, usually applied to the <form>. Otherwise, any required field without a value shows up as invalid on page load. This way, you may choose when to activate them (typically after form submission is attempted).
  • To reset the appearance of the form (for instance, in the case of dynamic form submissions using AJAX), remove the .was-validated class from the <form> again after submission.
  • As a fallback, isValid and isValidated properties may be used on validated components instead of the pseudo-classes for server-side validation. They do not require a .was-validated parent class.
  • Due to constraints in how CSS works, we cannot (at present) apply styles to a <label> that comes before a form control in the DOM without the help of custom JavaScript.
  • All modern browsers support the constraint validation API, a series of JavaScript methods for validating form controls.
  • Feedback messages may utilize the browser defaults (different for each browser, and unstylable via CSS) or our custom feedback styles with additional HTML and CSS.
  • You may provide custom validity messages with validFeedback and invalidFeedback properties for validated components.

With that in mind, consider the following demos for our custom form validation styles, optional server-side classes, and browser defaults.

Browser defaults

Not interested in custom validation feedback messages or writing JavaScript to change form behaviors? All good, you can use the browser defaults. Try submitting the form below. Depending on your browser and OS, you’ll see a slightly different style of feedback.

While these feedback styles cannot be styled with CSS, you can still customize the feedback text through JavaScript.

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Server side

We recommend using client-side validation, but in case you require server-side validation, you can indicate invalid and valid form fields with isValid and isValidated properties. Note that invalidFeedback and validFeedback are also supported with these properties.

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Supported elements

Validation styles are available for the following form controls and components:

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Tooltips

If your form layout allows it, you can add tooltipFeedback property for validFeedback, invalidFeedback properties to display validation feedback in a styled tooltip. Be sure to have a parent with position: relative on it for tooltip positioning. In the example below, our column classes have this already, but your project may require an alternative setup.

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Validation on event

Use validationEvent="event name" property for input and textarea or validateOnChange property for checkbox and radio inputs to validate elements on specific event instead of submit.

Adding validation attributes to input element such as minLength or pattern will show validation message based on your default browser validation response for invalid element. Add proper information about validation requirements in title attribute for better accessibility.

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Customizing

Validation states can be customized via Sass with the $form-validation-states map. Located in our _variables.scss file, this Sass map is looped over to generate the default valid/invalid validation states. Included is a nested map for customizing each state’s color. While no other states are supported by browsers, those using custom styles can easily add more complex form feedback.

Please note that we do not recommend customizing these values without also modifying the form-validation-state mixin.

This is the Sass map from _variables.scss. Override this and recompile your Sass to generate different states:

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This is the loop from forms/_validation.scss. Any modifications to the above Sass map will be reflected in your compiled CSS via this loop:

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