Trouble with ModelState on datetime field

Trouble with ModelState on datetime field

In our ASP MVC 3 site, we want the user to be able to enter an incomplete
form, save that record to the database, and come back to the form later.
If there were fields entered incorrectly we want those error message to
appear when the user hits save.
A problem is occurring specific to the date of birth field, however. If a
user enters an incorrect date such as 14/01/2011, when the user hits save
and the model object POSTs back to the controller action, the date of
birth comes through as blank. It then fails the if (ModelState.IsValid)
condition, does not save to the database, and is sent back to the view
with a blank date of birth.
Is there a way to allow the user to enter an incorrect date in this field,
keep that value and POST back to the view with that value and the error
message that would normally be generated by the model? Since we are using
a jQuery input mask, the value entered will always be numeric and in
MM/DD/YYYY format.
Model
[DisplayName("Date of Birth")]
[DisplayFormat(DataFormatString = "{0:MM/dd/yyyy}",
ApplyFormatInEditMode = true)]
public DateTime? Birthdate { get; set; }
Controller
[HttpPost]
public ActionResult Edit(Monet.Models.AgentTransmission
agenttransmission)
{
//Date of birth field is null right here in 'agenttransmission'
object if
//user enters incorrect value/date
//redirect if security is not met.
if (!Security.IsModifier(User)) return RedirectToAction("Message",
"Home", new { id = 1 });
//Tax Id security
ViewBag.FullSSN = Security.IsFullSsn(User);
try
{
agenttransmission =
AgentTransmissionValidator.ReformatFields(agenttransmission);
ViewBag.ErrorMessage =
AgentTransmissionValidator.ValidateAgent(agenttransmission);
if (ModelState.IsValid)
{
//Whole bunch of code to determine if input is
complete/incomplete
//Save the record
db.Entry(agenttransmission).State = EntityState.Modified;
db.SaveChanges();
} //end if model state valid
}
catch (DbEntityValidationException dbEx)
{
ViewBag.ErrorMessage = "An error has occurred, we apologize
for the incovenience. IT has been notified and will resolve
the issue shortly.";
SendEmail.ErrorMail(Common.ErrorCheck.CombineDbErrors(dbEx));
}
catch (Exception ex)
{
ViewBag.ErrorMessage = ErrorCheck.FriendlyError(ex);
SendEmail.ErrorMail(ex);
}
return View(agenttransmission);
}
View
<div class="M-editor-label">
@Html.LabelFor(model => model.Birthdate)<span
class="req">*</span>
</div>
<div class="M-editor-field">
@Html.EditorFor(model => model.Birthdate)
@Html.ValidationMessageFor(model => model.Birthdate)
</div>