MVC custom validation: compare two dates

I've created a custom ValidationAttribute that compares 2 dates and makes sure that the second date is greater than the first:

public sealed class IsDateAfter : ValidationAttribute, IClientValidatable
{
    private readonly string testedPropertyName;
    private readonly bool allowEqualDates;

    public IsDateAfter(string testedPropertyName, bool allowEqualDates = false)
    {
        this.testedPropertyName = testedPropertyName;
        this.allowEqualDates = allowEqualDates;
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var propertyTestedInfo = validationContext.ObjectType.GetProperty(this.testedPropertyName);
        if (propertyTestedInfo == null)
        {
            return new ValidationResult(string.Format("unknown property {0}", this.testedPropertyName));
        }

        var propertyTestedValue = propertyTestedInfo.GetValue(validationContext.ObjectInstance, null);

        if (value == null || !(value is DateTime))
        {
            return ValidationResult.Success;
        }

        if (propertyTestedValue == null || !(propertyTestedValue is DateTime))
        {
            return ValidationResult.Success;
        }

        // Compare values
        if ((DateTime)value >= (DateTime)propertyTestedValue)
        {
            if (this.allowEqualDates)
            {
                return ValidationResult.Success;
            }
            if ((DateTime)value > (DateTime)propertyTestedValue)
            {
                return ValidationResult.Success;
            }
        }

        return new ValidationResult(FormatErrorMessage(validationContext.DisplayName));
    }

    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        var rule = new ModelClientValidationRule
        {
            ErrorMessage = this.ErrorMessageString,
            ValidationType = "isdateafter"
        };
        rule.ValidationParameters["propertytested"] = this.testedPropertyName;
        rule.ValidationParameters["allowequaldates"] = this.allowEqualDates;
        yield return rule;
    }

CalendarEntry class: ...

public virtual DateTime StartDate { get; set; }
    
[IsDateAfter("StartDate", true, ErrorMessage="End date needs to be after start date")]
public virtual DateTime EndDate { get; set; }

VIEW:

$.validator.unobtrusive.adapters.add(
    'isdateafter', ['propertytested', 'allowequaldates'], function (options) {
    options.rules['isdateafter'] = options.params;
    options.messages['isdateafter'] = options.message;
});
$.validator.addMethod("isdateafter", function(value, element, params) {
    alert(params.propertytested);
    var startdatevalue = $('input[name="' + params.propertytested + '"]').val();
    if (!value || !startdatevalue) return true;
    return (params.allowequaldates) ? Date.parse(startdatevalue) <= Date.parse(value) : Date.parse(startdatevalue) < Date.parse(value);
}, '');

This works fine when the CalendarEntry is not wrapped inside another class. HOWEVER, when I use a view model like so:

    public class TrainingDateEditViewModel
    {
        #region Properties

        /// <summary>
        /// Gets or sets CalendarEntry.
        /// </summary>
        public CalendarEntry CalendarEntry { get; set; }
....

The client validation no longer works because the html output produced is this:

<input type="text" value="" name="CalendarEntry.EndDate" id="CalendarEntry_EndDate" data-val-isdateafter-propertytested="StartDate" data-val-isdateafter-allowequaldates="True" data-val-isdateafter="End date needs to be after start date" data-val="true">

And the

data-val-isdateafter-propertytested="StartDate" and IT SHOULD BE: "CalendarEntry.StartDate".

How would I make it so that it would know to bind to "CalendarEntry.StartDate" rule.ValidationParameters["propertytested"] = this.testedPropertyName; // HERE IT SHOULD BE FULL NAME??? HOW??

thanks

You need to modify your client-side script to check for the tested element's prefix, and add the prefix (if any) to your selector, as follows:

$.validator.addMethod("isdateafter", function(value, element, params) {
    var parts = element.name.split(".");
    var prefix = "";
    if (parts.length > 1)
        prefix = parts[0] + ".";
    var startdatevalue = $('input[name="' + prefix + params.propertytested + '"]').val();
    if (!value || !startdatevalue) 
        return true;    
    return (params.allowequaldates) ? Date.parse(startdatevalue) <= Date.parse(value) :
        Date.parse(startdatevalue) < Date.parse(value);
});

Do not forget to include the client side inside this code. It tooks me hours to find that this was missing!

(function ($) {

  // your code here..

})(jQuery);

Just to fix a small error in counsellorben's javascript: the "(params.allowequaldates)" will be interpreted as a string (which will have a value of "False" or "True"), but that string will always be evaluated to true, thus always allowing equal dates. If you also want to allow for more levels of nesting of your objects than just 1, then you will get:

$.validator.addMethod("isdateafter", function(value, element, params) {
    var parts = element.name.split(".");
    var prefix = "";
    for (var i = 0; i < parts.length - 1; i++)
       prefix = parts[i] + ".";
    var startdatevalue = $('input[name="' + prefix + params.propertytested + '"]').val();
    if (!value || !startdatevalue) 
        return true;    
    var allowequal = params.allowequaldates.toLowerCase === "true";
    return allowequal ? Date.parse(startdatevalue) <= Date.parse(value) :
        Date.parse(startdatevalue) < Date.parse(value);
});

In the last answer there were some missing parenthesis on the call to toLowerCase, here is an updated version with document ready and the $.validator.unobtrusive...-part:

$(function () {
    $.validator.addMethod("isdateafter", function(value, element, params) {
        var parts = element.name.split(".");
        var prefix = "";
        for (var i = 0; i < parts.length - 1; i++) {
            prefix = parts[i] + ".";
        }
        
        var startdatevalue = $('input[name="' + prefix + params.propertytested + '"]').val();
       
        if (!value || !startdatevalue) return true;    

        var allowequal = params.allowequaldates.toLowerCase() === "true";
        return allowequal ? Date.parse(startdatevalue) <= Date.parse(value) :
            Date.parse(startdatevalue) < Date.parse(value);
    });
    $.validator.unobtrusive.adapters.add('isdateafter', 
        ['propertytested', 'allowequaldates'], 
        function (options) {
            options.rules['isdateafter'] = options.params;
            options.messages['isdateafter'] = options.message;
        });
});