ASP.NET MVC: Handling upload exceeding maxRequestLength

Question

When uploading a file in my MVC site, I\'m looking to handle upload failures due to the user exceeding maxRequestLength more gracefully than for example showing a generic custom

Answer 1

Here's a workaround: set the maxRequestLength property in your web.config to some high value. Then write a custom validation attribute:

public class MaxFileSize : ValidationAttribute
{
    public int MaxSize { get; private set; }

    public MaxFileSize(int maxSize)
    {
        MaxSize = maxSize;
    }

    public override bool IsValid(object value)
    {
        var file = value as HttpPostedFileBase;
        if (file != null)
        {
            return file.ContentLength < MaxSize;
        }
        return true;
    } 
}

which could be used to decorate your view model with:

public class MyViewModel
{
    [Required]
    [MaxFileSize(1024 * 1024, ErrorMessage = "The uploaded file size must not exceed 1MB")]
    public HttpPostedFileBase File { get; set; }
}

then you could have a controller:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        var model = new MyViewModel();
        return View(model);
    }

    [HttpPost]
    public ActionResult Index(MyViewModel model)
    {
        if (!ModelState.IsValid)
        {
            return View(model);
        }

        // TODO: Process the uploaded file: model.File

        return RedirectToAction("Success");
    }
}

and finally a view:

@model MyViewModel

@using (Html.BeginForm(null, null, FormMethod.Post, new { enctype = "multipart/form-data" }))
{
    <div>
       @Html.LabelFor(x => x.File)
       <input type="file" name="file" />
       @Html.ValidationMessageFor(x => x.File)
    </div>

    <p><input type="submit" value="Upload"></p>
}