Nick Riggs, Web Developer

I like performing validation using Data Annotations in ASP.NET MVC. However, with complex scenarios, I find myself having to choose a different path. One complex scenario is “contingent scenario” also called “dependent scenario”:

Check out this simple class to demonstrate a contingent validation problem.

private class Person
{
    [Required]
    public string FirstName { get; set; }
    [Required]
    public string LastName { get; set; }
    [Required]
    public bool Married { get; set; }
    public string MaidenName { get; set; }
}

Let’s say our validation rule is: “If the user selects Married=true, then the user must also provide a MaidenName”.

Data Annotations, currently, don’t handle validating this rule.  And, I can’t make a custom class-level annotation because that will only validate the model and not the individual item.

What I would like to write is:

[Required]
public bool Married { get; set; }

[RequiredIfTrue("Married")]
public string MaidenName { get; set; }

This simple yet unsupported markup fueled a couple of late night hack-a-thons.   Now, I am pleased to announce the fruits of my labor… my first opensource project: “MVC Foolproof Validation”

http://foolproof.codeplex.com/

MVC Foolproof Validation extends the Data Annotation validation provided in ASP.NET MVC. Initial efforts are focused on contingent validation.

Some examples of what is possible:

public class SignUpViewModel
{
    [Required]
    public string Password { get; set; }

    [EqualTo("Password", ErrorMessage="Passwords do not match.")]
    public string RetypePassword { get; set; }
}

public class EventViewModel
{
    [Required]
    public string Name { get; set; }

    [Required]
    public DateTime Start { get; set; }

    [Required]
    [GreaterThan("Start")]
    public DateTime End { get; set; }
}

Status of the project:
It’s in development, but it works.
Client validation is supported, both standard MVC and jQuery flavors.

Download the source, take a look and make suggestions. I feel strongly that Foolproof is something the community could really use. I hope to roll out a first release in a couple of weeks.

http://foolproof.codeplex.com/