You must have a view with the proper Java Script script references in place for client side validation to work as you see here.
MVC uses validation attributes in addition to type metadata from model properties to validate data and display any error messages using Java Script.
There’s a lot to be said about configuration in ASP.
It will help ensure that application configuration is in a well-defined state.
When you use MVC to render form elements from a model using Tag Helpers or HTML helpers it will add HTML 5 data- attributes in the form elements that need validation, as shown below.
MVC generates the Client-side validation prevents submission until the form is valid.
Other types of validation include applying patterns to data to enforce business rules, such as a credit card, phone number, or email address.
Validation attributes make enforcing these requirements much simpler and easier to use.
Most of the properties are required and several string properties have length requirements.However, some validation rules are specific to your business, as they’re not just generic data validation such as ensuring a field is required or that it conforms to a range of values.For these scenarios, custom validation attributes are a great solution.Some apps will choose to follow a standard convention for dealing with model validation errors, in which case a filter may be an appropriate place to implement such a policy.You should test how your actions behave with valid and invalid model states.