asp.net mvc - Trouble with ModelState on datetime field -

in our asp mvc 3 site, want user able enter incomplete form, save record database, , come form later. if there fields entered incorrectly want error message appear when user hits save.

a problem occurring specific date of birth field, however. if user enters incorrect date such 14/01/2011, when user hits save , model object posts controller action, date of birth comes through blank. fails if (modelstate.isvalid) condition, not save database, , sent view blank date of birth.

is there way allow user enter incorrect date in field, keep value , post view value , error message generated model? since using jquery input mask, value entered numeric , 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 null right here in 'agenttransmission' object if         //user enters incorrect value/date          //redirect if security 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 determine if input complete/incomplete                  //save record                 db.entry(agenttransmission).state = entitystate.modified;                 db.savechanges();             } //end if model state valid         }         catch (dbentityvalidationexception dbex)         {             viewbag.errormessage = "an error has occurred, apologize incovenience. has been notified , resolve 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> 

as queti mporta suggested, problem that, when post back, model binder tries parse "14/01/2011" datetime? , fails, uses default value instead. nullable type, default null, why blank.

if change model to...

[displayname("date of birth")] [displayformat(dataformatstring = "{0:mm/dd/yyyy}", applyformatineditmode = true)] public string birthdate { get; set; } // note: string instead of datetime? 

...the user can enter format mm/dd/yyyy, when posted back, stored in string.

you need add logic (in controller or somewhere accessible controller) attempt parse yourself:

datetime birthdate; var isdatevalid = datetime.tryparse(agenttransmission.birthdate, out birthday); if (!isdatevalid ) modelstate.addmodelerror("birthdate", "birthday needs valid date.");