Multiple custom validation attributes on a class mvc

Question

I am creating a example for better understanding.

[CustomValidator("Property1","Property2", ErrorMessage= "Error1")]
[CustomValidator("Property3","Property4", ErrorMessage= "Error1")]
public class MyViewModel
{
    public string Property1 {get; set;}
    public string Property2 {get; set;}
    public string Property3 {get; set;}
    public string Property4 {get; set;}
}

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = false)]
public class CustomValidator : ValidationAttribute
{
    All the required stuff is written.
}

Only the second validator (or the last one in the list) gets fired and ignores the first one. I am not sure if this is the right approach for this scenario. Any suggestions?

Answer 1

if you are using Linq to SQL why not try something like this

add a rule violations class to handle rule violations

public class RuleViolation
{
    public string ErrorMessage { get; private set; }
    public string PropertyName { get; private set; }
    public RuleViolation(string errorMessage)
    {
        ErrorMessage = errorMessage;
    }
    public RuleViolation(string errorMessage, string propertyName)
    {
        ErrorMessage = errorMessage;
        PropertyName = propertyName;
    }
}

now on your data class

[Bind(Exclude="ID")]
public partial class Something
{
    public bool IsValid
    {
        get { return (GetRuleViolations().Count() == 0); }
    }

    public IEnumerable<RuleViolation> GetRuleViolations()
    {
        if (String.IsNullOrEmpty(Name.Trim()))
            yield return new RuleViolation("Name Required", "Name");
        if (String.IsNullOrEmpty(LocationID.ToString().Trim()))
            yield return new RuleViolation("Location Required", "LocationID");
        yield break;
    }

    partial void OnValidate(ChangeAction action)
    {
        if (!IsValid)
            throw new ApplicationException("Rule violations prevent saving");
    }

}

and in your controller's methods for updating, use the updatemodel method for changing properties

Something something = somethingRepo.GetSomething(id);
try
{
    //update something
    UpdateModel(something);
    somethingRepo.Save();
    return RedirectToAction("Index");
}
catch
{
    ModelState.AddRuleViolations(something.GetRuleViolations());
    return View(something);
}

this way you can just add rules to your data class as it changes and it will be reflected in your updates, etc

Answer 2

you dont really need all that code use data annotations by creating a metaData class for your model link text

that should set you on the right road also read up on html helpers and buddy classes ( this is what they call em)