Compare Dates DataAnnotations Validation asp.net mvc

Question

Lets say I have a StartDate and an EndDate and I wnt to check if the EndDate is not more then 3 months apart from the Start Date

public class DateCompare : V         


        

Answer 1

1. Dates

Entity:

[MetadataType(typeof(MyEntity_Validation))]
public partial class MyEntity
{
}
public class MyEntity_Validation
{
    [Required(ErrorMessage="'Date from' is required")]
    public DateTime DateFrom { get; set; }

    [CompareDatesValidatorAttribute("DateFrom")]  
    public DateTime DateTo { get; set; }
}

Attribute:

 public sealed class CompareDatesValidatorAttribute : ValidationAttribute
{
    private string _dateToCompare;  
    private const string _errorMessage = "'{0}' must be greater or equal'{1}'";  

    public CompareDatesValidatorAttribute(string dateToCompare)
        : base(_errorMessage)
    {
        _dateToCompare = dateToCompare;
    }

    public override string FormatErrorMessage(string name)
    {
        return string.Format(_errorMessage, name, _dateToCompare);
    } 

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var dateToCompare = validationContext.ObjectType.GetProperty(_dateToCompare);
        var dateToCompareValue = dateToCompare.GetValue(validationContext.ObjectInstance, null);
        if (dateToCompareValue != null && value != null && (DateTime)value < (DateTime)dateToCompareValue) 
        {
            return new ValidationResult(FormatErrorMessage(validationContext.DisplayName));
        }
        return null;
    }
}

2. Password

Entity:

   public string Password { get; set; }

    [Compare("Password", ErrorMessage = "ConfirmPassword must match Password")]
    public string ConfirmPassword { get; set; }

I hope it helps