Adding validation

We have already touched on validation; there are some built-in functionalities in the input components and EditForm to handle validation.

One way to add validation to our form is to use DataAnnotations. Using DataAnnotations, we don’t have to write any custom logic to ensure the data in the form is correct; instead, we can add attributes to the data model and let DataAnnotationsValidator take care of the rest.

There are a bunch of DataAnnotations instances in .NET already that we can use; we can also build our own annotations.

Some of the built-in data annotations are as follows:

• Required: This makes the field required.
• Email: This will check that the entered value is an email address.
• MinLength: This will check that the number of characters is not fewer than the value specified.
• MaxLength: This will check that the number of characters is not exceeded.
• Range: This will check that the value is within a specific...