Question

In my asp.net mvc 3 project I use [Required] attributes on properties that need to be validated. Also I use ModelState.AddModelError to add errors to the same properties (with attributes). The errors added with the second approach doesn’t show up. What could be the reason?

Here is the code:

1) property with attibute

[Required(ErrorMessage = "Product name is required")]
        public string Name { get; set; }

2) in controller action method

if (p.Name.Length < 3)
   ModelState.AddModelError("Name",
      "Product name should be at least 3 characters long");

3) in the view

@Html.EditorFor(i => i.CurrentItem.Product.Name)
        Html.ValidationMessageFor(i => i.CurrentItem.Product.Name)
        @Html.ValidationMessage("Name")

So, mabby I can’t use attributes and ModelState both?

Answer 1

You can achieve the same thing by adding a StringLength attribute:

[StringLength(100, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 3)]

Where 100 is the max length and 3 the minimum length.