How to bind dropdownlist data to complex class?
- by chobo2
Hi
I am using asp.net mvc 2.0(default binding model) and I have this problem.
I have a strongly typed view that has a dropdownlist
<%= Html.DropDownList("List", "-----")%>
Now I have a model class like
Public class Test()
{
public List { get; set; }
public string Selected {get; set;}
}
Now I have in my controller this
public ActionResult TestAction()
{
Test ViewModel = new Test();
ViewModel.List = new SelectList(GetList(), "value", "text", "selected");
return View(Test);
}
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult TestAction(Test ViewModel)
{
return View();
}
Now when I load up the TestAction page for the first time it populates the dropdown list as expected.
Now I want to post the selected value back to the server(the dropdownlist is within a form tag with some other textboxes). So I am trying to bind it automatically when it comes in as seen (Test ViewModel)
However I get this big nasty error.
Server Error in '/' Application.
No parameterless constructor defined for this object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.MissingMethodException: No parameterless constructor defined for this object.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[MissingMethodException: No parameterless constructor defined for this object.]
System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache) +98
System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean skipCheckThis, Boolean fillCache) +241
System.Activator.CreateInstance(Type type, Boolean nonPublic) +69
System.Activator.CreateInstance(Type type) +6
System.Web.Mvc.DefaultModelBinder.CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType) +403
System.Web.Mvc.DefaultModelBinder.BindSimpleModel(ControllerContext controllerContext, ModelBindingContext bindingContext, ValueProviderResult valueProviderResult) +544
System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +479
System.Web.Mvc.DefaultModelBinder.GetPropertyValue(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor, IModelBinder propertyBinder) +45
System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor) +658
System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext controllerContext, ModelBindingContext bindingContext) +147
System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Object model) +98
System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +2504
System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +548
System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor) +474
System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +181
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +830
System.Web.Mvc.Controller.ExecuteCore() +136
System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +111
System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +39
System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__4() +65
System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +44
System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +42
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +141
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +54
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +52
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8836913
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184
So how can I do this?
