ASP.NET MVC partial views: input name prefixes

Question

You can extend Html helper class by this :

using System.Web.Mvc.Html


 public static MvcHtmlString PartialFor<TModel, TProperty>(this HtmlHelper<TModel> helper, System.Linq.Expressions.Expression<Func<TModel, TProperty>> expression, string partialViewName)
    {
        string name = ExpressionHelper.GetExpressionText(expression);
        object model = ModelMetadata.FromLambdaExpression(expression, helper.ViewData).Model;
        var viewData = new ViewDataDictionary(helper.ViewData)
        {
            TemplateInfo = new System.Web.Mvc.TemplateInfo
            {
                HtmlFieldPrefix = name
            }
        };

        return helper.Partial(partialViewName, model, viewData);

    }

and simply use it in your views like this :

<%= Html.PartialFor(model => model.Child, "_AnotherViewModelControl") %>

and you will see everything is ok!

so far, i was searching for the same thing I have found this recent post:

http://davybrion.com/blog/2011/01/prefixing-input-elements-of-partial-views-with-asp-net-mvc/

<% Html.RenderPartial("AnotherViewModelControl", Model.Child, new ViewDataDictionary
{
    TemplateInfo = new System.Web.Mvc.TemplateInfo { HtmlFieldPrefix = "Child1" }
})
%>

My answer, based on the answer of Mahmoud Moravej including the comment of Ivan Zlatev.

    public static MvcHtmlString PartialFor<TModel, TProperty>(this HtmlHelper<TModel> helper, System.Linq.Expressions.Expression<Func<TModel, TProperty>> expression, string partialViewName)
    {
            string name = ExpressionHelper.GetExpressionText(expression);
            object model = ModelMetadata.FromLambdaExpression(expression, helper.ViewData).Model;
            StringBuilder htmlFieldPrefix = new StringBuilder();
            if (helper.ViewData.TemplateInfo.HtmlFieldPrefix != "")
            {
                htmlFieldPrefix.Append(helper.ViewData.TemplateInfo.HtmlFieldPrefix);
                htmlFieldPrefix.Append(name == "" ? "" : "." + name);
            }
            else
                htmlFieldPrefix.Append(name);

            var viewData = new ViewDataDictionary(helper.ViewData)
            {
                TemplateInfo = new System.Web.Mvc.TemplateInfo
                {
                    HtmlFieldPrefix = htmlFieldPrefix.ToString()
                }
            };

        return helper.Partial(partialViewName, model, viewData);
    }

Edit: The Mohamoud's answer is incorrect for nested partial rendering. You need to append the new prefix to the old prefix, only if it is necessary. This was not clear in the latest answers (:

Using MVC2 you can achieve this.

Here is the strongly typed view:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MvcLearner.Models.Person>" %>

<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
    Create
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

    <h2>Create</h2>

    <% using (Html.BeginForm()) { %>
        <%= Html.LabelFor(person => person.Name) %><br />
        <%= Html.EditorFor(person => person.Name) %><br />
        <%= Html.LabelFor(person => person.Age) %><br />
        <%= Html.EditorFor(person => person.Age) %><br />
        <% foreach (String FavoriteFoods in Model.FavoriteFoods) { %>
            <%= Html.LabelFor(food => FavoriteFoods) %><br />
            <%= Html.EditorFor(food => FavoriteFoods)%><br />
        <% } %>
        <%= Html.EditorFor(person => person.Birthday, "TwoPart") %>
        <input type="submit" value="Submit" />
    <% } %>

</asp:Content>

Here is the strongly typed view for the child class (which must be stored in a subfolder of the view directory called EditorTemplates):

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<MvcLearner.Models.TwoPart>" %>

<%= Html.LabelFor(birthday => birthday.Day) %><br />
<%= Html.EditorFor(birthday => birthday.Day) %><br />

<%= Html.LabelFor(birthday => birthday.Month) %><br />
<%= Html.EditorFor(birthday => birthday.Month) %><br />

Here is the controller:

public class PersonController : Controller
{
    //
    // GET: /Person/
    [AcceptVerbs(HttpVerbs.Get)]
    public ActionResult Index()
    {
        return View();
    }

    [AcceptVerbs(HttpVerbs.Get)]
    public ActionResult Create()
    {
        Person person = new Person();
        person.FavoriteFoods.Add("Sushi");
        return View(person);
    }

    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult Create(Person person)
    {
        return View(person);
    }
}

Here are the custom classes:

public class Person
{
    public String Name { get; set; }
    public Int32 Age { get; set; }
    public List<String> FavoriteFoods { get; set; }
    public TwoPart Birthday { get; set; }

    public Person()
    {
        this.FavoriteFoods = new List<String>();
        this.Birthday = new TwoPart();
    }
}

public class TwoPart
{
    public Int32 Day { get; set; }
    public Int32 Month { get; set; }
}

And the output source:

<form action="/Person/Create" method="post"><label for="Name">Name</label><br /> 
    <input class="text-box single-line" id="Name" name="Name" type="text" value="" /><br /> 
    <label for="Age">Age</label><br /> 
    <input class="text-box single-line" id="Age" name="Age" type="text" value="0" /><br /> 
    <label for="FavoriteFoods">FavoriteFoods</label><br /> 
    <input class="text-box single-line" id="FavoriteFoods" name="FavoriteFoods" type="text" value="Sushi" /><br /> 
    <label for="Birthday_Day">Day</label><br /> 
    <input class="text-box single-line" id="Birthday_Day" name="Birthday.Day" type="text" value="0" /><br /> 

    <label for="Birthday_Month">Month</label><br /> 
    <input class="text-box single-line" id="Birthday_Month" name="Birthday.Month" type="text" value="0" /><br /> 
    <input type="submit" value="Submit" /> 
</form>

Now this is complete. Set a breakpoint in the Create Post controller action to verify. Don't use this with lists however because it wont work. See my question on using EditorTemplates with IEnumerable for more on that.

This is an old question, but for anyone arriving here looking for a solution, consider using EditorFor, as suggested in a comment in https://stackoverflow.com/a/29809907/456456. To move from a partial view to an editor template, follow these steps.

1. Verify that your partial view is bound to ComplexType.

2. Move your partial view to a subfolder EditorTemplates of the current view folder, or to the folder Shared. Now, it is an editor template.

3. Change @Html.Partial("_PartialViewName", Model.ComplexType) to @Html.EditorFor(m => m.ComplexType, "_EditorTemplateName"). The editor template is optional if it's the only template for the complex type.

Html Input elements will automatically be named ComplexType.Fieldname.