Semi-Complex View Model Property Validation in ASP.NET MVC 3 - asp.net-mvc

Question

I am struggling to complete a server-client validation solution for a semi-complex scenario. I have a core type called DateRange:
public class DateRange {
public DateRange (DateTime? start, DateTime? end) { ... }
public DateTime? Start { get; private set; }
public DateTime? End { get; private set; }
}
I have a view model like:
public class MyViewModel {
public DateRange Period { get; set; }
}
I have a %mvcproject%\Views\Shared\EditorTemplates\DateRange.cshtml like:
#model MyCore.DateRange
#Html.Editor("Start", "Date")
#Html.Editor("End", "Date")
I also have a DateRangeModelBinder to bind the two form inputs into the DateRange property. The problem I'm having is with a DateRangeRequiredAttribute:
public class DateRangeRequired : ValidationAttribute, IClientValidatable,
IMetadataAware
{
private const string DefaultErrorMessage =
"{0} is required.";
public DateRangeRequired(bool endIsRequired = true)
: base(() => DefaultErrorMessage)
{
EndIsRequired = endIsRequired;
}
public bool EndIsRequired { get; set; }
public override bool IsValid(object value)
{
if (value == null)
{
return false;
}
if (!value.GetType().IsAssignableFrom(typeof(DateRange)))
{
throw new ArgumentException("Value is not a DateRange.");
}
var dateRange = value as DateRange;
return (dateRange.Start.HasValue && !EndIsRequired) ||
(dateRange.Start.HasValue && dateRange.End.HasValue && EndIsRequired);
}
public override string FormatErrorMessage(string name)
{
return string.Format(CultureInfo.CurrentCulture, ErrorMessageString, name);
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var rule = new ModelClientValidationRule()
{
ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
ValidationType = "daterangerequired"
};
rule.ValidationParameters.Add("endisrequired", EndIsRequired.ToString().ToLower());
yield return rule;
}
public void OnMetadataCreated(ModelMetadata metadata)
{
metadata.DataTypeName = "DateRange";
}
}
I can't get it to hook up to the two inputs. It's almost like there needs to be a ValidatorTemplate that pairs with the EditorTemplate because of the split inputs. Any ideas? Let me know if additional clarification is needed.

Answer 1

You haven't shown exactly how your custom DateRangeRequiredAttribute implementation looks like, so let me suggest an example:
public class DateRangeRequiredAttribute : ValidationAttribute, IClientValidatable
{
private readonly string _otherProperty;
public DateRangeRequiredAttribute(string otherProperty)
{
_otherProperty = otherProperty;
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var property = validationContext.ObjectType.GetProperty(_otherProperty);
if (property == null)
{
return new ValidationResult(string.Format(CultureInfo.CurrentCulture, "Unknown property {0}", _otherProperty));
}
var otherValue = property.GetValue(validationContext.ObjectInstance, null);
if (!(value is DateTime) || !(otherValue is DateTime))
{
return new ValidationResult(string.Format(CultureInfo.CurrentCulture, "The two properties to compare must be of type DateTime"));
}
if ((DateTime)value >= (DateTime)otherValue)
{
return new ValidationResult(FormatErrorMessage(validationContext.DisplayName));
}
return null;
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var rule = new ModelClientValidationRule
{
ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
ValidationType = "daterange"
};
rule.ValidationParameters.Add("other", "*." + _otherProperty);
yield return rule;
}
}
then you could decorate your view model with it:
public class DateRange
{
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:d}")]
[DateRangeRequired("End", ErrorMessage = "Please select a start date before the end date")]
public DateTime? Start { get; set; }
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:d}")]
[Required]
public DateTime? End { get; set; }
}
and finally in the view register the adapter:
jQuery.validator.unobtrusive.adapters.add(
'daterange', ['other'], function (options) {
var getModelPrefix = function (fieldName) {
return fieldName.substr(0, fieldName.lastIndexOf(".") + 1);
};
var appendModelPrefix = function (value, prefix) {
if (value.indexOf('*.') === 0) {
value = value.replace('*.', prefix);
}
return value;
};
var prefix = getModelPrefix(options.element.name),
other = options.params.other,
fullOtherName = appendModelPrefix(other, prefix),
element = $(options.form).find(':input[name="' + fullOtherName + '"]')[0];
options.rules['daterange'] = element;
if (options.message) {
options.messages['daterange'] = options.message;
}
}
);
jQuery.validator.addMethod('daterange', function (value, element, params) {
// TODO: some more advanced date checking could be applied here
// currently it uses the current browser culture setting to perform
// the parsing. If you needed to use the server side culture, this code
// could be adapted respectively
var date = new Date(value);
var otherDate = new Date($(params).val());
return date < otherDate;
}, '');
After reading this pornography, you might consider using FluentValidation.NET which renders this extremely simple validation scenario a couple of lines to implement (which is how such simple validation scenarios should be done). I would strongly recommend you this library. I am using it in all my projects because I am sick of DataAnnotations for validation. They are so pretty limited.