This post shows you how you can do client side, unobtrusive validation on your MVC form.

It assumes you have already set up your Model, View and Controller, but you just need to know how to get it to validate on the client side.

You need to make sure you are referencing the following scripts in your page:

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
 <script src="/scripts/jquery.validate.min.js"></script>
 <script src="/scripts/jquery.validate.unobtrusive.min.js"></script>
 <script src="/scripts/jquery.unobtrusive-ajax.js"></script>

If you don't have any of the scripts above, you can install them via nuget

PM> Install-Package Microsoft.jQuery.Unobtrusive.Validation
PM> Install-Package Microsoft.jQuery.Unobtrusive.Ajax

You need to enable client validation and unobtrusive validation, which can be done for the whole site, by adding these settings to the web.config app settings:

 <add key="ClientValidationEnabled" value="true" />
 <add key="UnobtrusiveJavaScriptEnabled" value="true" /> 

or for just one page you can add this to the top of your view:

@{ 
 Html.EnableClientValidation();
 Html.EnableUnobtrusiveJavaScript();
}

That should be all you need.

Now when you enter content to the form, if it is empty or invalid, it should trigger the validation messages straight away.

Please feel free to comment or share this post. I hope it has been useful for you.

Paul