Imagine you're building an single page application that has a couple of forms. How are you going to validate those forms? Because we don't want to refresh the page submitting the form as usual isn't possible. Adding validation logic to the JavaScript side of things would just duplicate the validation logic already present on the server. Wouldn't it be nice if we could validate our front end forms using back end logic?

A while ago Jeffrey Way published a lesson on Object-Oriented forms in the Vue 2.0 series that does just that. Because I wanted to use Jeffrey's way of doing things in some real life projects I decided to put his code (and some extra niceties) in JavaScript package called spatie/form-backend-validation. Though it could work in other frameworks it is primarily built with a Laravel back end in mind.

To get started using the package it's best to watch the aforementioned free video on Object-Oriented forms. That'll explain the train of thought behind it. In short the package provides a Form class to submit all form values to the server. It will collect any errors the server sends back. Using a Vue component we can easily collect all values and display all errors. And this can all happen without having to refresh the page.

To help you understand it even better, we've created an example app in which the package is installed. These are the most important pieces:

a Blade view that contains the form that needs to be validated

a Vue component that makes use of the `Form` class the package provides

the controller where the actual validation is performed

If you set up the example app and hit it the / route of the app you'll see a form for you to toy around with.