Question

I’m trying to develop an ASP.NET application “by the book”; I have my Web Forms implement MVP pattern, my presenter talks only to Services layer that than talks to a bunch of repositories all sharing my own EF ObjectContext. So far so good. Now I’m tackling the front end and I have a dilemma…

Lets say I have an asp:TextBox control named txtDateOfBirth and submit button. When a user clicks the button, I need to send data from ASPX to presenter to Service to …. but the problem is that in the end I don’t need String, but DateTime? and I don’t know the best place to make the conversion:

• Should I put a validator in ASPX page and then in code-behind do the conversion?
• Or should I collect a bunch of strings from the form, create a request for the service containing only strings, and than have my Business Model do the try/convert and report errors?

What do you recommend? Any insight is appreciated…

EDIT: OK, after having read and tried all of your suggestions, I decided to go with the following:

1. Code-behind and APSX are responsible for data type conversions. I
   decided to go with simple CompareValidator and check for the
   appropriate type so code-behind can surely convert it.
2. Request that goes from presenter to service layer is appropriately
   typed.
3. All other validation is being done by business layer (including
   string lengths, required or not, range, …)

Answer 1

If I understood that correctly, you have an textbox in your WebForm where the user writes something that should be a date, right?

There are somethings you can do:

• You can use a mask for the textbox, formated for your date format. That will send you a string back that looks like a date (check how later). I think asp:textbox have this option; anyway, MaskedEdit controls have it too: http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/MaskedEdit/MaskedEdit.aspx
• You can use a model class, then validate the input according to the Custom Decisions for the fields in that model. See here: Is it possible to use Data Annotations for MVC in an ASP.NET WEBFORM Business Object Class?
• You can validate through Javascript in your WebForm, before sending it back. It is kind of messy, anyway.
• Or you can just validate that in your code-behind, and reload your page if something is wrong with an error message somewhere. It is what the DataAnnotations do automatically in MVC.