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DataAnnotation and optional DateTime values

I am working with an HTML form that accepts 4 dates, two of which are optional. These dates are inserted into the MS SQL database, so I check the boundaries of the DateTime variables that are passed from the form to SqlDateTime.MinValue and SqlDateTime.MaxValue. This is what my model looks like:

[Required] [DisplayName("Planned Start Date")] [CustomValidation(typeof(Goal), "ValidateGoalDate")] public object planned_start_date { get; set; } [DisplayName("Actual Start Date")] [CustomValidation(typeof(Goal), "ValidateGoalDate")] public object start_date { get; set; } [Required] [DisplayName("Planned End Date")] [CustomValidation(typeof(Goal), "ValidateGoalDate")] public object planned_end_date { get; set; } [DisplayName("Actual Start Date")] //[CustomValidation(typeof(Goal), "ValidateGoalDate")] public object end_date { get; set; }

And my custom validator:

  public static ValidationResult ValidateGoalDate(DateTime goalDate) { //* this does not appear to work ever because the optional field does //* not ever get validated. if (goalDate == null || goalDate.Date == null) return ValidationResult.Success; if (goalDate.Date < (DateTime)SqlDateTime.MinValue) return new ValidationResult("Date must be after " + SqlDateTime.MinValue.Value.ToShortDateString()); if (goalDate.Date > (DateTime)SqlDateTime.MaxValue) return new ValidationResult("Date must be before " + SqlDateTime.MaxValue.Value.ToShortDateString() ); return ValidationResult.Success; }

The problem occurs whenever you submit the form without additional values. In my controller, my ModelState.IsValid returns false, and I get a validation error message:

"Failed to convert the value of type" null "to" System.DateTime ", as expected, using the GoalManager.Models.Goal.ValidateGoalDate method. Must enter a valid date.

Having selected the code, I see that the custom validator does not start in optional fields, but when I remove the DataAnnotation from these optional fields, I do not return an error. If the user does not insert the date in the field, I want to insert NULL into the table. How do I tell Validator that I don’t want the error to check for an empty (or null) date to ignore it and insert zero into the database?

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3 answers

The DateTime that your custom validator takes as a parameter is not null in your example ... If you set the DateTime to a null value, it should fix your problem.

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Here's an implementation of what @Rikon said:

 public static ValidationResult ValidateGoalDate(DateTime? goalDate) {
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This will (possibly) avoid the exception, but I think you need to keep track of it with more code inside the method:

 public static ValidationResult ValidateGoalDate(DateTime goalDate = new DateTime())

If you still have a problem returning the ModelState.IsValid model, you can add something like this to the controller:

 foreach (var state in ModelState) { if (state.Key == "start_date") state.Value.Errors.Clear(); }

(I'm sure there are better ways to do this, but it doesn't matter, at least it's self-evident)

By the way, it is impractical to completely disable the scan, as this will allow the use of security exploits for injection. For more information about validation and how you can also disable it for each field on the client side, read the following: http://msdn.microsoft.com/en-us/library/aa479045.aspx#aspplusvalid%5Fclientside

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