MaxLength Attribute not generating client-side validation attributes

Question

I have a curious problem with ASP.NET MVC3 client-side validation. I have the following class:

public class Instrument : BaseObject
{
    public int Id { get         


        

Answer 1

I had this same problem and I was able to solve it by implementing the IValidatableObject interface in my view model.

public class RegisterViewModel : IValidatableObject
{
    /// 

    /// Error message for Minimum password
    /// 
    public static string PasswordLengthErrorMessage => $"The password must be at least {PasswordMinimumLength} characters";

    /// 

    /// Minimum acceptable password length
    /// 
    public const int PasswordMinimumLength = 8;

    /// 

    /// Gets or sets the password provided by the user.
    /// 
    [Required]
    [DataType(DataType.Password)]
    [Display(Name = "Password")]
    public string Password { get; set; }

    /// 

    /// Only need to validate the minimum length
    /// 
    /// ValidationContext, ignored
    /// List of validation errors
    public IEnumerable Validate(ValidationContext validationContext)
    {
        var errorList = new List();
        if ((Password?.Length ?? 0 ) < PasswordMinimumLength)
        {
            errorList.Add(new ValidationResult(PasswordLengthErrorMessage, new List() {"Password"}));
        }
        return errorList;
    }
}

The markup in the Razor is then...

    @Html.LabelFor(m => m.Password)
    @Html.PasswordFor(m => m.Password, new { @class = "form-control input-lg" }
    
Must contain: 8 characters, 1 upper-case, 1 lower-case
    
    @Html.ValidationMessagesFor(m => m.Password, new { @class = "text-danger" })

This works really well. If I attempt to use [StringLength] instead then the rendered HTML is just not correct. The validation should render as:

The Password should be a minimum of 8 characters long.

With the StringLengthAttribute the rendered HTML shows as a ValidationSummary which is not correct. The funny thing is that when the validator fails the submit is still blocked!