Conditional required validation or field mandatory depends on another field MVC 4

I have experienced this situation that when I need to make a field mandatory if the user has entered a value in another field (or a particular value for that field).

Here is my example, I have two radio buttons says “Do you have the purchase receipt?” with options “yes” or “no”. If the user has selected “yes”, I need them to specify the date of the purchase as well.


Now the headache is, I can’t make “Purchase Date” required field. Because if user selects “no”, they don’t need to enter the “Purchase Date”. After I did some research and lookup from the internet. I find this solution on StackOverflow. It has a few bugs and I fixed them and shared over here in my blog.

I created a RequiredIfAttribute,

public class RequiredIfAttribute : ValidationAttribute, IClientValidatable
    protected RequiredAttribute _innerAttribute;

    public string DependentProperty { get; set; }
    public object TargetValue { get; set; }

    public bool AllowEmptyStrings
            return _innerAttribute.AllowEmptyStrings;
            _innerAttribute.AllowEmptyStrings = value;

    public RequiredIfAttribute(string dependentProperty, object targetValue)
        _innerAttribute = new RequiredAttribute();
        DependentProperty = dependentProperty;
        TargetValue = targetValue;

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        // get a reference to the property this validation depends upon
        var containerType = validationContext.ObjectInstance.GetType();
        var field = containerType.GetProperty(DependentProperty);

        if (field != null)
            // get the value of the dependent property
            var dependentValue = field.GetValue(validationContext.ObjectInstance, null);
            // trim spaces of dependent value
            if (dependentValue != null && dependentValue is string)
                dependentValue = (dependentValue as string).Trim();

                if (!AllowEmptyStrings && (dependentValue as string).Length == 0)
                    dependentValue = null;

            // compare the value against the target value
            if ((dependentValue == null && TargetValue == null) ||
                (dependentValue != null && (TargetValue.Equals("*") || dependentValue.Equals(TargetValue))))
                // match => means we should try validating this field
                if (!_innerAttribute.IsValid(value))
                    // validation failed - return an error
                    return new ValidationResult(FormatErrorMessage(validationContext.DisplayName), new[] { validationContext.MemberName });

        return ValidationResult.Success;

    public virtual IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
        var rule = new ModelClientValidationRule
            ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
            ValidationType = "requiredif",

        string depProp = BuildDependentPropertyId(metadata, context as ViewContext);

        // find the value on the control we depend on;
        // if it's a bool, format it javascript style 
        // (the default is True or False!)
        string targetValue = (TargetValue ?? "").ToString();
        if (TargetValue is bool)
            targetValue = targetValue.ToLower();

        rule.ValidationParameters.Add("dependentproperty", depProp);
        rule.ValidationParameters.Add("targetvalue", targetValue);

        yield return rule;

    private string BuildDependentPropertyId(ModelMetadata metadata, ViewContext viewContext)
        // build the ID of the property
        string depProp = viewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(DependentProperty);
        // unfortunately this will have the name of the current field appended to the beginning,
        // because the TemplateInfo's context has had this fieldname appended to it. Instead, we
        // want to get the context as though it was one level higher (i.e. outside the current property,
        // which is the containing object, and hence the same level as the dependent property.
        var thisField = metadata.PropertyName + "_";
        if (depProp.StartsWith(thisField))
            // strip it off again
            depProp = depProp.Substring(thisField.Length);
        return depProp;

2. Create js validation and js unobtrusive validation, (I put them in document.ready() callback)

    function (value, element, parameters) {
        var id = '#' + parameters['dependentproperty'];

        // get the target value (as a string, 
        // as that's what actual value will be)
        var targetvalue = parameters['targetvalue'];
        targetvalue = (targetvalue == null ? '' : targetvalue).toString();

        // get the actual value of the target control
        // note - this probably needs to cater for more 
        // control types, e.g. radios
        var control = $(id);
        var controltype = control.attr('type');
        var actualvalue =
            (controltype === 'checkbox' ||  controltype === 'radio')  ?
            control.attr('checked').toString() :

        // if the condition is true, reuse the existing 
        // required field validator functionality
        if ($.trim(targetvalue) === $.trim(actualvalue) || ($.trim(targetvalue) === '*' && $.trim(actualvalue) !== ''))
            return $
              this, value, element, parameters);

        return true;

    ['dependentproperty', 'targetvalue'],
    function (options) {
        options.rules['requiredif'] = {
            dependentproperty: options.params['dependentproperty'],
            targetvalue: options.params['targetvalue']
        options.messages['requiredif'] = options.message;

3. For the Model,

        public bool HasReceipt { get; set; }

         [RequiredIf("HasReceipt", true, ErrorMessage = "You must enter purchase date")]
        [Display(Name="Purchase Date")]
        public DateTime? PurchaseDate { get; set; }

4. When reference this validation js, I notice that it only works before the unobtrusive javascript,

    <script src="~/Scripts/jquery.unobtrusive-ajax.min.js"></script>
    <script src="~/Scripts/jquery.validate.min.js"></script>
    <script src="~/Scripts/jquery.validate.requiredif.js"></script>
    <script src="~/Scripts/jquery.validate.unobtrusive.min.js"></script>

5. Now you have your conditional required validations.

There are many scenarios like this,


If you have entered an Address field, you must enter Suburb, City.

If you have selected yes for a credit card, you must enter the credit card digits.

If you have subscribed a service, you must enter a valid email.

And many more.

Validation Summary is not cleared after Ajax.Form successfully posted, MVC 3

My scenario is after the invalid form values are posted through ajax.form, and the validation summary is displaying on the view. After I filled in all the required fields and posted the form with valid values, the post back data is correctly displaying, but the validation summary is remaining on the page.

Here are some code snippets,

The view contains two date picker (textbox) which are required fields.

    @model ClosedTicketByProductReportViewModel
    @using (Ajax.BeginForm("ClosedTicketByProductReport", "Report", new AjaxOptions { UpdateTargetId = "closedTicketByProductGrid", LoadingElementId = "loadingcontainer" }))
        <div class="control-group">
            Date From
            <div class="controls">
                @Html.TextBoxFor(p =&gt; p.DateFromForClosedProduct, new Dictionary { { "class", "small" }, { "type", "date" }, { "data-datepicker", "datepicker" } })
        <div class="control-group">
            Date To
            <div class="controls">
                @Html.TextBoxFor(p =&gt; p.DateToForClosedProduct, new Dictionary { { "class", "small" }, { "type", "date" }, { "data-datepicker", "datepicker" } })

        Generate Report

Here is the view model I created for the view,

    public class ClosedTicketByProductReportViewModel

        [Required(ErrorMessage = "Please select Date From")]
        public DateTime? DateFromForClosedProduct { get; set; }

        [Required(ErrorMessage = "Please select Date To")]
        public DateTime? DateToForClosedProduct { get; set; }

        //report data
        public List Cases { get; set; }


After I click submit without entering any dates, it displays the error messages as expected.


Then I enter the dates, and click submit again. The post back data is retrieved from controller action, but the validation summary remains on the page. As you can see the validation errors on the textbox itself are gone. Ajax.Form is only lack of support on the validation summaries.


Here is my fix, I don’t think it is great, but it is a work around.

    @using (Ajax.BeginForm("ClosedTicketByProductReport", "Report", new AjaxOptions { OnSuccess = "HideValidationSummary", UpdateTargetId = "closedTicketByProductGrid", LoadingElementId = "loadingcontainer" }))
    { }

I created a javascript function and call it on OnSuccess = "HideValidationSummary, the javascript function just hide the validation summary div.

function HideValidationSummary() {

If anyone come across my blog post and has a better solution, please leave me a message. Much appreciated.

Render modal dialog from a PartialView, client side validation not working

While I am using JQuery to render a modal popup, and the popup content is read from a controller action with a partialview returned. The client side validation is not fired.

Here is a piece of sample code, I am using bootstrap modal to render the modal popup.

var url = "/Feed/Save/" + id;
        $.get(url, null, function (html) {

You need to add a line to parse unobtrusive validator,


After the modified the code, it all works fine,

var url = "/Feed/Save/" + id;
        $.get(url, null, function (html) {

EmailAttribute for validation using data annotations in MVC 3

Here we create an email validation attribute. By implementing the IClientValidatable interface (which will enable the Unobtrusive javascript validation) & inheriting from RegularExpressionAttribute.

    public class EmailAttribute : RegularExpressionAttribute, IClientValidatable
        public EmailAttribute()
            : base(@"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" +
                   @"\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" +

        public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
            var errorMessage = FormatErrorMessage(metadata.GetDisplayName());

            yield return new EmailValidationRule(errorMessage);

    public class EmailValidationRule : ModelClientValidationRule
        public EmailValidationRule(string errorMessage)
            ErrorMessage = errorMessage;
            ValidationType = "email";

Then tie your validator to the model, it will validate both client & server side.



public string Email { get;set; }


It requires the web.config settings to enable client validations.

<add key="ClientValidationEnabled" value="true"/>
<add key="UnobtrusiveJavaScriptEnabled" value="true"/>