Showing Different fields in EditorForModel vs. DisplayForModel modes in MVC2

Question

I have a viewmodel that has an int StateID field and a string StateName field like so:

public class DepartmentViewModel : BaseViewModel, IModelWithId
{
    // only show in edit mode
    public int StateId { get; set; }

    // only show in display mode
    public string StateName { get; set; }
}

I have a read only view that uses DisplayForModel and an update view that uses EditorForModel. I want the DisplayForModel view to show the StateName property, and the EditorForModel view use the StateID property (I am actually rendering a dropdownlist based on this).

I have not been able to figure out how to decorate my viewmodel properties to create this behavior.

Answer 1

A comment on CodeGrue's answer.

Make the attribute inherit IMetadataAware instead. That way you don't need to build your own DataAnnotationsModelMetadataProvider.

The new attribute would become something like:

[AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
public sealed class RenderModeAttribute : Attribute, IMetadataAware
{
    public RenderMode RenderMode { get; set; }

    public RenderModeAttribute(RenderMode renderMode)
    {
        RenderMode = renderMode;
    }

    public void OnMetadataCreated(ModelMetadata metadata)
    {
        switch (RenderMode)
        {
            case RenderMode.DisplayModeOnly:
                metadata.ShowForDisplay = true;
                metadata.ShowForEdit = false;
                break;

            case RenderMode.EditModeOnly:
                metadata.ShowForDisplay = false;
                metadata.ShowForEdit = true;
                break;

            case RenderMode.None:
                metadata.ShowForDisplay = false;
                metadata.ShowForEdit = false;
                break;
        }
    }
}

public enum RenderMode
{
    Any,
    EditModeOnly,
    DisplayModeOnly
}

Answer 2

I wanted a solution that was more generic, so I created a new attribute:

[AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
public sealed class RenderModeAttribute : Attribute
{
    public RenderMode RenderMode { get; set; }

    public RenderModeAttribute(RenderMode renderMode)
    {
        RenderMode = renderMode;
    }
}

public enum RenderMode
{
    Any,
    EditModeOnly,
    DisplayModeOnly
}

And included the following code in my custom DataAnnotationsModelMetadataProvider:

var renderModeAttribute = attributes.OfType<RenderModeAttribute>();
if (renderModeAttribute.Any())
{
    var renderMode = renderModeAttribute.First().RenderMode;
    switch (renderMode)
    {
        case RenderMode.DisplayModeOnly:
            metadata.ShowForDisplay = true;
            metadata.ShowForEdit = false;
            break;
        case RenderMode.EditModeOnly:
            metadata.ShowForDisplay = false;
            metadata.ShowForEdit = true;
            break;
    }
}

So that I could just decorate my model as so:

public class DepartmentViewModel    
{     
    [RenderMode(RenderMode.EditModeOnly)]   
    public int StateId { get; set; }     

    [RenderMode(RenderMode.DisplayModeOnly)]    
    public string StateName { get; set; }     
} 

Answer 3

Here is my custom provider, I add a None render mode

public class CustomModelMetadataProvider : DataAnnotationsModelMetadataProvider
{
    protected override ModelMetadata CreateMetadata(System.Collections.Generic.IEnumerable<System.Attribute> attributes, System.Type containerType, System.Func<object> modelAccessor, System.Type modelType, string propertyName)
    {
        var metadata = base.CreateMetadata(attributes, containerType, modelAccessor, modelType, propertyName);

        var renderModeAttribute = attributes.OfType<RenderModeAttribute>();
        if (renderModeAttribute.Any())
        {
            var renderMode = renderModeAttribute.First().RenderMode;
            switch (renderMode)
            {
                case RenderMode.DisplayModeOnly:
                    metadata.ShowForDisplay = true;
                    metadata.ShowForEdit = false;
                    break;

                case RenderMode.EditModeOnly:
                    metadata.ShowForDisplay = false;
                    metadata.ShowForEdit = true;
                    break;

                case RenderMode.None:
                    metadata.ShowForDisplay = false;
                    metadata.ShowForEdit = false;
                    break;
            }
        } 

        return metadata;
    }
}

Answer 4

Override the templates:

In ~/Shared/EditorTemplates/DepartmentViewModel.ascx put:

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<Namespace.DepartmentViewModel>" %>
<%= Html.LabelFor(x => x.StateId) %>
<%= Html.TextBoxFor(x => x.StateId) %>

And in your ~/Shared/DisplayTemplates/DepartmentViewModel.ascx:

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<Namespace.DepartmentViewModel>" %>
<div><%= Html.Encode(Model.StateName) %></div>