Rendering a ContentFolder as a Block to List Assets

Update: I'm an idiot. Fixed it up.

For content-heavy clients, we get the occasional request for listing file assets on the site for download. From what I can tell, there are a couple of options that require a bit of author effort, but I really wanted to provide something that is more suited to the best authoring experience offered by Episerver - drag and drop within Content Areas.

Knowing I can drag and drop most content types into a ContentArea and expect something to happen, I decided to give it a try using one of the asset panel ContentFolders. So I hover my mouse over a folder, casually hold down the mouse button, and drag the folder into an open area of the page. The field highlights! The folder drops in! It works!

Almost.

According to Episerver's documentation, "a content folder is used to structure content and has no visual appearance on the site." Meaning that the ContentFolder type has no Controller and no View.

Great. I can fix that. Code below.

Here's the part where I was an idiot. I was using the wrong parameter name in my Index method and therefore thought that the system was always returning null. Key lesson: make sure you're aligning with convention. So I deleted where I was explaining my workaround that I didn't need and am just including the final code below. This isn't production, but feel free to point out my other mistakes.

Controller:

using EPiServer.Core;
using EPiServer.Web.Mvc;
using System;
using System.Linq;
using System.Web.Mvc;
using System.Web.Routing;
using EPiServer;
using EPiServer.ServiceLocation;
using Alloy.Models.ViewModels;
using Alloy.Models.Media;
using Alloy.Business;

namespace Alloy.Controllers
{
    public class ContentFolderController : PartialContentController
    {
        private IContentRepository contentRepository => ServiceLocator.Current.GetInstance();
        // GET: ContentFolder
        public override ActionResult Index(ContentFolder currentContent)
        {
            if(currentContent != null)
            {
                var model = new ContentFolderViewModel();
                model.Name = currentContent.Name;

                var documents = contentRepository.GetChildren(currentContent.ContentLink);

                model.Documents = documents.Select(d => new DocumentViewModel() {
                    Name = d.Name,
                    Description = d.Description,
                    Url = d.GetUrl(),
                    FileSize = d.BinaryData.GetSize(),
                    EveryoneHasAccess = d.IsAvailableToEveryone()
                });

                return PartialView(model);
            }
            return PartialView();
        }
    }
}

View:

@model Alloy.Models.ViewModels.ContentFolderViewModel

<h3>@Model.Name</h3>
<ul>
@foreach (var doc in Model.Documents)
{
    <li>
        <a href="@doc.Url">@doc.Name</a>
        @if (!string.IsNullOrWhiteSpace(doc.Description))
        { <div>@Html.Raw(doc.Description)</div> }
        <div style="font-style: italic; color: #777">File size: @doc.FileSize</div>
    </li>
}
</ul>

ViewModels:

using System.Collections.Generic;

namespace Alloy.Models.ViewModels
{
    public class ContentFolderViewModel
    {
        public string Name { get; set; }
        public IEnumerable<DocumentViewModel> Documents { get; set; }
    }
}

namespace Alloy.Models.ViewModels
{
    public class DocumentViewModel
    {
        public string Name { get; set; }
        public string FileSize { get; set; }
        public string Url { get; set; }
        public string Description { get; set; }
        public bool EveryoneHasAccess { get; set; }
    }
}

Extensions:

using EPiServer.Core;
using EPiServer.Security;
using EPiServer.ServiceLocation;
using EPiServer.Web.Routing;
using System;
using System.Security.Principal;

namespace Alloy.Business
{
    public static class MediaExtensions
    {
        private static UrlResolver urlResolver => ServiceLocator.Current.GetInstance<UrlResolver>();
        private static PermissionService permissionService => ServiceLocator.Current.GetInstance<PermissionService>();

        public static string GetSize(this EPiServer.Framework.Blobs.Blob blob)
        {
            using (var blobReader = blob.OpenRead())
            {
                var l = blobReader.Length;
                if(l < 1000)
                {
                    return $"{l} bytes";
                }
                if(l < 1000000)
                {
                    return $"{l / 1024} KB";
                }
                return $"{l / 1056478} MB";
            }
        }

        public static Boolean IsAvailableToEveryone<T>(this T content) where T : IContent
        {
            return content.RoleHasAccess(new[] { "Everyone" }, AccessLevel.Read);
        }

        public static Boolean RoleHasAccess<T>(this T content, string[] roles, AccessLevel accessLevel) where T : IContent
        {
            var securedContent = content as ISecurable;
            var descriptor = securedContent.GetSecurityDescriptor();
            var identity = new GenericIdentity("doesn't matter");
            var principal = new GenericPrincipal(identity, roles);
            return descriptor.HasAccess(principal, accessLevel);
        }

        public static string GetUrl<T>(this T content) where T : IContent
        {
            return urlResolver.GetUrl(content.ContentLink);
        }
    }
}