Question

I have an ASP.NET MVC 3 Controller Action that accepts an object as follows:

    //// model.ReferenceNumber equals "-1"
    public ActionResult EditApplication(EditApplicationViewModel model)
    {
        if (!ModelState.IsValid)
        {
                  ...
        }

        // Existing Applicant
        model.ReferenceNumber = "";
        var msg = this.RenderPartialViewToString("_ExistingApplication", model);
    }

When the request is received, the “model.ReferenceNumber” equals “-1”. Even after setting the property on the model to empty string “”, still the results of “RenderPartialViewToString” shows the value of “-1” in the “Value” property of the “input” HTML field.

Any idea why this is happening?

This is the code used to render the partial view:
http://craftycodeblog.com/2010/05/15/asp-net-mvc-render-partial-view-to-string/

public static string RenderPartialViewToString(this Controller controller, string viewName, object model)
{
    if (string.IsNullOrEmpty(viewName))
        viewName = controller.ControllerContext.RouteData.GetRequiredString("action");

    controller.ViewData.Model = model;

    using (var sw = new StringWriter())
    {
        var viewResult = ViewEngines.Engines.FindPartialView(controller.ControllerContext, viewName);
        var viewContext = new ViewContext(controller.ControllerContext, viewResult.View, controller.ViewData, controller.TempData, sw);
        viewResult.View.Render(viewContext, sw);

        return sw.GetStringBuilder().ToString();
    }
}

Thanks

Answer 1

When you modify the value of some model property in your controller qction make sure you remove it from the modelstate as well:

ModelState.Remove("ReferenceNumber");
model.ReferenceNumber = "new value";
var msg = this.RenderPartialViewToString("_ExistingApplication", model);