R – MVC Model Validation Programmatic Registration support

asp.net-mvcasp.net-mvc-2asp.net-mvc-2-validationattributes

Today (15th Jan 2010) Scott blogged about the ASP.NET MVC2 model-validation

http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx

Anyone knows how can someone add validation rules at runtime programmatically ?

"Programmatic Registration" is a similar functionality supported by ValidationAspects

// register lambda syntax validation functions
typeof(User).GetProperty("Name").AddValidation<string>((name, context) => 
  { if (!Exists(name)) { throw new ValidationException("Username is unknown"); } } );

// register validation factories (classes)
typeof(User).GetProperty("Name").AddValidation(new [] { new NotNullOrEmpty()} );

// don't like strings?
TypeOf<User>.Property(user => user.Name).AddValidation(new [] { new NotNullOrEmpty()} );

Best Answer

To provide custom metadata you'll have to implement the abstract class ModelMetadataProvider and register it inside your global.asax:

           ModelMetadataProviders.Current = new ConventionMetadataProvider();

This isn't adding validation attributes at runtime. Your simply providing ALL the validation information into the ModelMetadata classes which are then read by the HTML.EditorFor bits.

Related Solutions

Asp.net-mvc – ASP.NET MVC Html.ValidationSummary(true) does not display model errors

I believe the way the ValidationSummary flag works is it will only display ModelErrors for string.empty as the key. Otherwise it is assumed it is a property error. The custom error you're adding has the key 'error' so it will not display in when you call ValidationSummary(true). You need to add your custom error message with an empty key like this:

ModelState.AddModelError(string.Empty, ex.Message);

C# – File Upload ASP.NET MVC 3.0

You don't use a file input control. Server side controls are not used in ASP.NET MVC. Checkout the following blog post which illustrates how to achieve this in ASP.NET MVC.

So you would start by creating an HTML form which would contain a file input:

@using (Html.BeginForm("Index", "Home", FormMethod.Post, new { enctype = "multipart/form-data" }))
{
    <input type="file" name="file" />
    <input type="submit" value="OK" />
}

and then you would have a controller to handle the upload:

public class HomeController : Controller
{
    // This action renders the form
    public ActionResult Index()
    {
        return View();
    }

    // This action handles the form POST and the upload
    [HttpPost]
    public ActionResult Index(HttpPostedFileBase file)
    {
        // Verify that the user selected a file
        if (file != null && file.ContentLength > 0) 
        {
            // extract only the filename
            var fileName = Path.GetFileName(file.FileName);
            // store the file inside ~/App_Data/uploads folder
            var path = Path.Combine(Server.MapPath("~/App_Data/uploads"), fileName);
            file.SaveAs(path);
        }
        // redirect back to the index action to show the form once again
        return RedirectToAction("Index");        
    }
}

Best Answer

Related Solutions

Asp.net-mvc – ASP.NET MVC Html.ValidationSummary(true) does not display model errors

C# – File Upload ASP.NET MVC 3.0

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