What are the differences between [DataType (DataType.EmailAddress)] and [EmailAddress]

Hope this clears up ...

As you noted, attributes DataType

are mostly used for formatting, not validation. The reason it works :

• @Html.EditorFor
  
  renders HTML5 <input type="email" ....
  
  which favors the client / browser for validation. If the browser complies, then client-side validation is performed. It will work because the client confirmed it for you (this is not a server side validation )

You can test it out by changing @Html.EditorFor

to @Html.TextBoxFor

in your view, which will render the input field as <input type="text" ...>

(standard text input field, not HTML5 email

).

Test example

Given a model with something like this:

public class User
{
    [Required(ErrorMessage = "Email must be provided")]
    [DataType(DataType.EmailAddress, ErrorMessage = "this doesn't do email format validation")]        
    [EmailAddress(ErrorMessage = "Not a valid Email")] //Comment un-comment to see effect
    public string EmailAddress { get; set; }

    [Required(ErrorMessage = "Name must be provided")]        
    public string Name { get; set; }
}

      

        
        
        
      

    

View using @Html.TextBoxFor

instead @Html.EditorFor

to render HTML5 client side validation in your test:

@Html.TextBoxFor(model => model.EmailAddress,....

      

        
        
        
      

    

And a controller like this:

public ActionResult CheckUser(User user)
{
    ViewBag.Foo = string.Empty;
    if(Request.HttpMethod == HttpMethod.Post.ToString())
    {
        ViewBag.Foo = ModelState.IsValid ? "User Model validated" : "Failed Model Validation";
    }
    return View();
}

      

        
        
        
      

    

If you:

• comment [EmailAddress]
  
  attribute, leaving only [DataType(DataType.EmailAddress)]
  
  your model valid with any text (no email format validation)
  • if you put "foo" your model is "valid" no error message.
• leave it you will get a server side email format confirmation
  • if you put "foo" it will crash and give an error message "Not a valid Email"
    
    

Hth ...