Question

I just created a sample MVC3 application to learn validation. It is using DataAnnotations. I have created a custom ValidationAttribute named CustomStartLetterMatch. It is implementing “System.Web.Mvc.IClientValidatable”. I have corresponding client-side code written with unobtrusive jQuery. This is working as expected.

About the custom validator: It compares the first name input and last name input. It throws error if first character of both of them are not same.

As I said, the application is working fine. But when I looked at the rule.ValidationType = "greaterdate"; I got confused. I wanted to change it to something else like “anotherDefaultType”. When I am changing it, it fails with jQuery error.

1. What is the reason for this?
2. What are the available ValidationTypes?
3. What is the suggested approach to change the ValidationType in this scenari

CODE:

using System;
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;
namespace MyValidationTEST
{
    public class Person
    {
    [Required(ErrorMessage = "First name required")]
    public string FirstName { get; set; }

    [CustomStartLetterMatch("FirstName")]
    [StringLength(5,ErrorMessage = "Must be under 5 characters")]
    public string LastName { get; set; }

    [Range(18,50,ErrorMessage="Must be between 18 and 50")]
    public int Age { get; set; }

}



public sealed class CustomStartLetterMatch : ValidationAttribute, System.Web.Mvc.IClientValidatable 
{

    private const string _defaultErrorMessage = " First letter of '{0}' must be same as first letetr of '{1}'";
    private string _basePropertyName;

    public CustomStartLetterMatch(string basePropertyName)
        : base(_defaultErrorMessage)
    {
        _basePropertyName = basePropertyName;
    }


    //Override FormatErrorMessage Method
    public override string FormatErrorMessage(string name)
    {
        return string.Format(_defaultErrorMessage, name, _basePropertyName);
    }


    //Override IsValid
    protected override ValidationResult IsValid(object value, System.ComponentModel.DataAnnotations.ValidationContext validationContext)
    {
        //Get PropertyInfo Object
        var basePropertyInfo = validationContext.ObjectType.GetProperty(_basePropertyName);
        var baseValue = (string)basePropertyInfo.GetValue(validationContext.ObjectInstance, null);
        var currentValue = (string)value;


        string firstLetterBaseValue = baseValue.Substring(0, 1);
        string firstLetterCurrentValue = currentValue.Substring(0, 1);

        //Comparision
        if (!string.Equals(firstLetterBaseValue, firstLetterCurrentValue))
        {
            var message = FormatErrorMessage(validationContext.DisplayName);
            return new ValidationResult(message);
        }

        //Default return - This means there were no validation error
        return null;
    }


    public IEnumerable<System.Web.Mvc.ModelClientValidationRule> GetClientValidationRules(System.Web.Mvc.ModelMetadata metadata, System.Web.Mvc.ControllerContext context)
    {
        var rule = new System.Web.Mvc.ModelClientValidationRule();
        rule.ErrorMessage = FormatErrorMessage(metadata.GetDisplayName());
        rule.ValidationParameters.Add("other", _basePropertyName);
        rule.ValidationType = "greaterdate";
        yield return rule;
    }



}

}

VIEW

@model MyValidationTEST.Person

@{
ViewBag.Title = "Create";
}

<h2>Create</h2>

<script src="@Url.Content("~/Scripts/jquery-1.5.1.min.js")" type="text/javascript">  </script>

@*UnObtrusive*@
<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>



<script type="text/javascript">

/*Register adapter - addSingleVal*/
jQuery.validator.unobtrusive.adapters.addSingleVal("greaterdate", "other");


/*Validation type names in unobtrusive client validation rules must consist of only lowercase letters*/

/*Add Method*/
jQuery.validator.addMethod("greaterdate",
                                    function (val, element, other) 
                                    {

                                        var modelPrefix = element.name.substr(0, element.name.lastIndexOf(".") + 1)
                                        var otherVal = $("[name=" + modelPrefix + other + "]").val();

                                        if (val && otherVal) 
                                        {
                                            var lastNameFirstLetter = val.substr(0, 1);
                                            var firstNameFirstLetter = otherVal.substr(0, 1);

                                            if (lastNameFirstLetter != firstNameFirstLetter) 
                                            {
                                                return false;
                                            }
                                        }
                                        return true;
                                    });


</script>


@using (Html.BeginForm()) {
@Html.ValidationSummary(true)
<fieldset>
    <legend>Person</legend>

    <div class="editor-label">
        @Html.LabelFor(model => model.FirstName)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.FirstName)
        @Html.ValidationMessageFor(model => model.FirstName)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.LastName)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.LastName)
        @Html.ValidationMessageFor(model => model.LastName)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.Age)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.Age)
        @Html.ValidationMessageFor(model => model.Age)
    </div>

    <p>
        <input type="submit" value="Create" />
    </p>
</fieldset>
}

<div>
@Html.ActionLink("Back to List", "Index")
</div>

CONTROLLER:

using System.Web.Mvc;
namespace MyValidationTEST.Controllers
{
public class RelativesController : Controller
{

    // GET: /Relatives/
    public ActionResult Index()
    {
        return View();
    }



    // GET: /Relatives/Create
    public ActionResult Create()
    {
        Person person = new Person();
        return View(person);
    }


    // POST: /Relatives/Create
    [HttpPost]
    public ActionResult Create(Person relativeToAdd)
    {
        if (ModelState.IsValid)
        {
            return RedirectToAction("Index");
        }
        return View(relativeToAdd);
    }

    }

 }

READING:

ASP.NET MVC3 – Custom validation attribute -> Client-side broken

Answer 1

I wanted to change it to something else like “anotherDefaultType”

You can use only lowercase letters for the ValidationType property:

rule.ValidationType = "anotherdefaulttype";

and then adapt your client script to reflect this modification:

jQuery.validator.unobtrusive.adapters.addSingleVal("anotherdefaulttype", "other");
jQuery.validator.addMethod("anotherdefaulttype", function (val, element, other) {
    ...
});