Stronglytyped html helper with different model for get and post - asp.net-mvc

Question

If a Get Action returns a View with a "Car" model. The view displays info from the object and takes input to post within a form to another action that takes an object of type "Payment"
The Model on the view is of type Car and gives me stronglytyped html support and some other features like displaytext. But for posting I there is no Htmlhelper support like TextBox(x => x.amount I need to make it like #Html.TextBox("Amount"...
Its possible, but is this the only option?

Answer 1

You can do this:
#{
var paymentHtml = Html.HtmlHelperFor<Payment>();
}
#paymentHtml.EditorFor(p => p.Amount)
with this extension method:
public static class HtmlHelperFactoryExtensions {
public static HtmlHelper<TModel> HtmlHelperFor<TModel>(this HtmlHelper htmlHelper) {
return HtmlHelperFor(htmlHelper, default(TModel));
}
public static HtmlHelper<TModel> HtmlHelperFor<TModel>(this HtmlHelper htmlHelper, TModel model) {
return HtmlHelperFor(htmlHelper, model, null);
}
public static HtmlHelper<TModel> HtmlHelperFor<TModel>(this HtmlHelper htmlHelper, TModel model, string htmlFieldPrefix) {
var viewDataContainer = CreateViewDataContainer(htmlHelper.ViewData, model);
TemplateInfo templateInfo = viewDataContainer.ViewData.TemplateInfo;
if (!String.IsNullOrEmpty(htmlFieldPrefix))
templateInfo.HtmlFieldPrefix = templateInfo.GetFullHtmlFieldName(htmlFieldPrefix);
ViewContext viewContext = htmlHelper.ViewContext;
ViewContext newViewContext = new ViewContext(viewContext.Controller.ControllerContext, viewContext.View, viewDataContainer.ViewData, viewContext.TempData, viewContext.Writer);
return new HtmlHelper<TModel>(newViewContext, viewDataContainer, htmlHelper.RouteCollection);
}
static IViewDataContainer CreateViewDataContainer(ViewDataDictionary viewData, object model) {
var newViewData = new ViewDataDictionary(viewData) {
Model = model
};
newViewData.TemplateInfo = new TemplateInfo {
HtmlFieldPrefix = newViewData.TemplateInfo.HtmlFieldPrefix
};
return new ViewDataContainer {
ViewData = newViewData
};
}
class ViewDataContainer : IViewDataContainer {
public ViewDataDictionary ViewData { get; set; }
}
}

Answer 2

If I understand your question correctly, here's some code I just wrote for one of my projects to do something similar. It doesn't require anything special like what was suggested by Max Toro.
#{
var teamHelper = new HtmlHelper<Team>(ViewContext, this);
}
#using (teamHelper.BeginForm())
{
#teamHelper.LabelFor(p => p.Name)
#teamHelper.EditorFor(p => p.Name)
}

Answer 3

Adding to the implementation by Max Toro, here are a couple more for when you have a non-null model but don't have static type information (these two methods need to be embedded into the implementation Max provides).
These methods work well when you have dynamically retrieved property names for a model and need to call the non-generic HtmlHelper methods that take a name instead of an expression:
#Html.TextBox(propertyName)
for example.
public static HtmlHelper HtmlHelperFor( this HtmlHelper htmlHelper, object model )
{
return HtmlHelperFor( htmlHelper, model, null );
}
public static HtmlHelper HtmlHelperFor( this HtmlHelper htmlHelper, object model, string htmlFieldPrefix )
{
var t = model.GetType();
var viewDataContainer = CreateViewDataContainer( htmlHelper.ViewData, model );
TemplateInfo templateInfo = viewDataContainer.ViewData.TemplateInfo;
if( !String.IsNullOrEmpty( htmlFieldPrefix ) )
templateInfo.HtmlFieldPrefix = templateInfo.GetFullHtmlFieldName( htmlFieldPrefix );
ViewContext viewContext = htmlHelper.ViewContext;
ViewContext newViewContext = new ViewContext( viewContext.Controller.ControllerContext, viewContext.View, viewDataContainer.ViewData, viewContext.TempData, viewContext.Writer );
var gt = typeof( HtmlHelper<> ).MakeGenericType( t );
return Activator.CreateInstance( gt, newViewContext, viewDataContainer, htmlHelper.RouteCollection ) as HtmlHelper;
}

Answer 4

For ASP.NET Core 2
public static class HtmlHelperFactoryExtensions
{
public static IHtmlHelper<TModel> HtmlHelperFor<TModel>(this IHtmlHelper htmlHelper)
{
return HtmlHelperFor(htmlHelper, default(TModel));
}
public static IHtmlHelper<TModel> HtmlHelperFor<TModel>(this IHtmlHelper htmlHelper, TModel model)
{
return HtmlHelperFor(htmlHelper, model, null);
}
public static IHtmlHelper<TModel> HtmlHelperFor<TModel>(this IHtmlHelper htmlHelper, TModel model, string htmlFieldPrefix)
{
ViewDataDictionary<TModel> newViewData;
var runtimeType = htmlHelper.ViewData.ModelMetadata.ModelType;
if (runtimeType != null && typeof(TModel) != runtimeType && typeof(TModel).IsAssignableFrom(runtimeType))
{
newViewData = new ViewDataDictionary<TModel>(htmlHelper.ViewData, model);
}
else
{
newViewData = new ViewDataDictionary<TModel>(htmlHelper.MetadataProvider, new ModelStateDictionary())
{
Model = model
};
}
if (!String.IsNullOrEmpty(htmlFieldPrefix))
newViewData.TemplateInfo.HtmlFieldPrefix = newViewData.TemplateInfo.GetFullHtmlFieldName(htmlFieldPrefix);
ViewContext newViewContext = new ViewContext(htmlHelper.ViewContext, htmlHelper.ViewContext.View, newViewData, htmlHelper.ViewContext.Writer);
var newHtmlHelper = htmlHelper.ViewContext.HttpContext.RequestServices.GetRequiredService<IHtmlHelper<TModel>>();
((HtmlHelper<TModel>)newHtmlHelper).Contextualize(newViewContext);
return newHtmlHelper;
}
}

Answer 5

If I understand your problem correctly, try:
#Html.EditorFor(x => x.Amount)
You could also create an editor template for Payment. See this page for details on doing this.
If I'm misunderstanding, some sample code might help.