MVC2 EditorTemplate for DropDownList

Question

I\'ve spent the majority of the past week knee deep in the new templating functionality baked into MVC2. I had a hard time trying to get a DropDownList template working. The b

Answer 1

I think I found a solution to make it work when using Html.EditorForModel(); When using EditorForModel(), MVC uses Object.ascx to loop through all properties of the model and calls the corresponding template for each property in the model. ASP.Net MVC out of the box has Object.ascx in code, but you can create your own Object.ascx. Just create an EditorTemplates subfolder in your Shared View folder. Create an Object.ascx file there. (read this post for more information: http://bradwilson.typepad.com/blog/2009/10/aspnet-mvc-2-templates-part-3-default-templates.html)

Here's my Object.ascx:

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %>
<%@ Import Namespace="WebAppSolutions.Helpers" %>
<% if (ViewData.TemplateInfo.TemplateDepth > 1) { %>
<%= ViewData.ModelMetadata.SimpleDisplayText%>
<% }
else { %>    
<% foreach (var prop in ViewData.ModelMetadata.Properties.Where(pm => pm.ShowForEdit && !ViewData.TemplateInfo.Visited(pm))) { %>

    <% var htmlFieldName = Html.HtmlFieldNameFor(prop.PropertyName);%>

    <% if (prop.HideSurroundingHtml) { %>
        <%= Html.Editor(htmlFieldName)%>
    <% }
       else { %>
        

            <% if (!String.IsNullOrEmpty(Html.Label(prop.PropertyName).ToHtmlString())) { %>
                <%= Html.Label(prop.PropertyName, Html.HtmlDisplayName(prop.PropertyName), prop.IsRequired)%>
            <% } %>
            <%= Html.Editor(prop.PropertyName, "", htmlFieldName)%>
            <%= Html.ValidationMessage(prop.PropertyName, "*") %>
        
    <% } %>
<% } %>

<% } %>

I have some custome code in my WebAppSolutions.Helpers for HtmlFieldNameFor and HtmlDisplayName. These helpers retrieve data from attributes applied to properties in the view model.

    public static String HtmlFieldNameFor(this HtmlHelper html, String propertyName)
    {
        ModelMetadata modelMetaData = GetModelMetaData(html, propertyName);
        return GetHtmlFieldName(modelMetaData, propertyName);
    }

    public static String HtmlDisplayName(this HtmlHelper html, String propertyName)
    {
        ModelMetadata modelMetaData = GetModelMetaData(html, propertyName);
        return modelMetaData.DisplayName ?? propertyName;
    }
    private static ModelMetadata GetModelMetaData(HtmlHelper html, String propertyName)
    {
        ModelMetadata modelMetaData = ModelMetadata.FromStringExpression(propertyName, html.ViewData);
        return modelMetaData;
    }

    private static String GetHtmlFieldName(ModelMetadata modelMetaData, string defaultHtmlFieldName)
    {
        PropertyExtendedMetaDataAttribute propertyExtendedMetaDataAttribute = GetPropertyExtendedMetaDataAttribute(modelMetaData);
        return propertyExtendedMetaDataAttribute.HtmlFieldName ?? defaultHtmlFieldName;
    }

The key to getting this to work using EditorModelFor() is this (should be line 20 or so in Object.ascx above):

<%= Html.Editor(prop.PropertyName, "", htmlFieldName)%>

prop.PropertyName is the property in the ViewModel containing the list of data that will become the DropDownList. htmlFieldName is the name of the property that's hidden that the DropDownList property is replacing. Make sense?

I hope this helps you.