I'll be tackling writing a custom date validation class tomorrow for a meeting app i'm working on at work that will validate if a given start or end date is A) less than the current date, or B) the start date is greater than the end date of the meeting (or vice versa).
I think this is probably a fairly common requirement. Can anyone point me in the direction of a blog post that might help me out in tackling this problem?
I'm using .net 3.5 so i can't use the new model validator api built into .NET 4. THe project i'm working on is MVC 2.
UPDATE: THe class i'm writing needs to extend the System.ComponentModel.DataAnnotations namespace. In .NET 4 there is a IValidateObject interface that you can implement, that makes this sort of thing an absolute doddle, but sadly i can't use .Net 4. How do i go about doing the same thing in .Net 3.5?
public sealed class DateStartAttribute : ValidationAttribute
{
public override bool IsValid(object value)
{
DateTime dateStart = (DateTime)value;
// Meeting must start in the future time.
return (dateStart > DateTime.Now);
}
}
public sealed class DateEndAttribute : ValidationAttribute
{
public string DateStartProperty { get; set; }
public override bool IsValid(object value)
{
// Get Value of the DateStart property
string dateStartString = HttpContext.Current.Request[DateStartProperty];
DateTime dateEnd = (DateTime)value;
DateTime dateStart = DateTime.Parse(dateStartString);
// Meeting start time must be before the end time
return dateStart < dateEnd;
}
}
and in your View Model:
[DateStart]
public DateTime StartDate{ get; set; }
[DateEnd(DateStartProperty="StartDate")]
public DateTime EndDate{ get; set; }
In your action, just check that ModelState.IsValid
. That what you're after?
I know this post is older, but, this solution I found is much better.
The accepted solution in this post won't work if the object has a prefix when it is part of a viewmodel.
i.e. the lines
// Get Value of the DateStart property
string dateStartString = HttpContext.Current.Request[DateStartProperty];
A better solution can be found here: ASP .NET MVC 3 Validation using Custom DataAnnotation Attribute:
New DateGreaterThan
attribute:
public sealed class DateGreaterThanAttribute : ValidationAttribute
{
private const string _defaultErrorMessage = "'{0}' must be greater than '{1}'";
private string _basePropertyName;
public DateGreaterThanAttribute(string basePropertyName) : base(_defaultErrorMessage)
{
_basePropertyName = basePropertyName;
}
//Override default FormatErrorMessage Method
public override string FormatErrorMessage(string name)
{
return string.Format(_defaultErrorMessage, name, _basePropertyName);
}
//Override IsValid
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
//Get PropertyInfo Object
var basePropertyInfo = validationContext.ObjectType.GetProperty(_basePropertyName);
//Get Value of the property
var startDate = (DateTime)basePropertyInfo.GetValue(validationContext.ObjectInstance, null);
var thisDate = (DateTime)value;
//Actual comparision
if (thisDate <= startDate)
{
var message = FormatErrorMessage(validationContext.DisplayName);
return new ValidationResult(message);
}
//Default return - This means there were no validation error
return null;
}
}
Usage example:
[Required]
[DataType(DataType.DateTime)]
[Display(Name = "StartDate")]
public DateTime StartDate { get; set; }
[Required]
[DataType(DataType.DateTime)]
[Display(Name = "EndDate")]
[DateGreaterThanAttribute("StartDate")]
public DateTime EndDate { get; set; }
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