DataAnotation to validate a model, how do I validate it so that the date is not in the future?

Question

I have the Review Model, I am trying to validate the model, so that when the user selects a date, it can't be the date in the future.

Review.cs

public class Review : BaseEntity{

    [Key]
    public int Id {get; set;}

    [Required(ErrorMessage="You need a restaurant name!")]
    public string RestaurantName {get; set;}

    [What do I put in here??]
    public DateTime Date {get; set;}


}

I am a newbie, and the documentation is kind of hard to understand.

Thank you so much for your help in advance.

Answer 1

You can create a custom validation attribute which does your custom logic and use that to decorate your property name.

public class DateLessThanOrEqualToToday : ValidationAttribute
{
    public override string FormatErrorMessage(string name)
    {
        return "Date value should not be a future date";
    }

    protected override ValidationResult IsValid(object objValue,
                                                   ValidationContext validationContext)
    {
        var dateValue = objValue as DateTime? ?? new DateTime();

        //alter this as needed. I am doing the date comparison if the value is not null

        if (dateValue.Date > DateTime.Now.Date)
        {
           return new ValidationResult(FormatErrorMessage(validationContext.DisplayName));
        }
        return ValidationResult.Success;
    }
}

Now in your view model, decorate your property name with this new custom attribute

[DateLessThanOrEqualToToday]
public DateTime Date { get; set; }

This custom validation attribute is primarly focusing on your specific validation logic. You can alter it to include more null checks, minimum value check etc as needed.