Welcome Alex

You use the contentloader along with the contentassetshelper.  you just get the children of the folder

http://world.episerver.com/Modules/Forum/Pages/Thread.aspx?id=81106&epslanguage=en

    Take a look at that link.  that should help you achieve your task.  If it still doesn't make sense feel free to keep posting and we will help you as much as we can

Let's say that file browser can be generalized and be created as block - you can drag it on the page and configure which folder to enlist (reference to that folder will be in `MediaFolder` property.

public class FileBrowserBlock : BaseBlockData
{
    [Display(Name = "Media folder", Order = 10)]
    [UIHint(UIHint.MediaFolder)]
    public virtual ContentReference MediaFolder { get; set; }
}

You may better need a controller for that.

public class FileBrowserBlockController : BlockController<FileBrowserBlock>
{
    private readonly IContentLoader loader;

    public FileBrowserBlockController(IContentLoader loader)
    {
        this.loader = loader;
    }
}

It's always good to have a view model:

public class FileBrowserBlockViewModel
{
    public FileBrowserBlockViewModel()
    {
        Files = new List<PdfFileMedia>();
    }

    public List<PdfFileMedia> Files { get; set; }
}

This will ensure that you have a access to content loader already injected in your controller.

Then you may have a default action on it that will enlist all PDF files:

public override ActionResult Index(FileBrowserBlock currentBlock)
{
    var model = new FileBrowserBlockViewModel();
    var rootFolder = loader.Get<ContentFolder>(currentBlock.MediaFolder);

Than you can enlist all files in that folder:

model.Files = rootFolder.GetChildren<PdfFileMedia>().Where(m => m.Category.Contains(Category.Find("Name of the catogory").ID));

`GetChildren` could defined as an extension method to `ContentFolder` type (may become really handy later):

public static IEnumerable<T> GetChildren<T>(this ContentFolder folder) where T : IContentData
{
    return ContentReference.IsNullOrEmpty(folder.ContentLink) ?
           Enumerable.Empty<T>() : 
           ServiceLocator.Current.GetInstance<IContentLoader>().GetChildren<T>(folder.ContentLink);
}

Then it's just a matter of painting the list on the screen :)

Thanks for the help everyone. I'm going to give it a go right now and let you know what solution worked best for me.

Valdis Iljuconoks solution is the one you want to follow.  

Valdis, I implemented a solution very similar to yours but now I get a strange error when the page renders that I don't understand.

The error is:

The model item passed into the dictionary is of type 'Castle.Proxies.LearningMaterialBlockProxy', but this dictionary requires a model item of type 'EPiServer.Templates.Alloy.Models.ViewModels.LearningMaterialBlockViewModel'.

Here is my code:

LearningMaterialBlock.cs

[ContentType(DisplayName = "LearningMaterialBlock", GUID = "11f6b61e-e780-49d7-a894-d8117f491c04", Description = "")]
    public class LearningMaterialBlock : SiteBlockData
    {
        [Display(Name = "Category", Order = 1)]
        public virtual CategoryList Category { get; set; }
    }

LearningMaterialBlockController.cs

public class LearningMaterialBlockController : BlockController<LearningMaterialBlock>
    {
        private readonly IContentLoader loader;

        public LearningMaterialBlockController(IContentLoader loader)
        {
            this.loader = loader;
        }

        public override ActionResult Index(LearningMaterialBlock currentBlock)
        {
            var model = new LearningMaterialBlockViewModel();
            var rootFolder = loader.Get<ContentFolder>(SiteDefinition.Current.GlobalAssetsRoot);
            model.Files = rootFolder.GetChildren<ListableItem>().Where(m => m.Category.Contains(currentBlock.Category.First()));

            return PartialView(model);
        }
    }

LearningMaterialBlockViewModel.cs

public class LearningMaterialBlockViewModel
    {
        public LearningMaterialBlockViewModel()
        {
            Files = new List<ListableItem>();
        }

        public IEnumerable<ListableItem> Files { get; set; }
    }

LearningMaterialBlock.cshtml

@model EPiServer.Templates.Alloy.Models.ViewModels.LearningMaterialBlockViewModel

@using EPiServer.Core
@using EPiServer.Web.Mvc.Html
@using EPiServer.Templates.Alloy.Models.Media

<div>
    @foreach (ListableItem item in Model.Files)
    {
        <div>
            <a href="">@item.Title</a>
            <p>@item.Description</p>
        </div>
    }
</div>

This is tricky sometimes. Solution: name your view different as your block type - apply Mvc particial naming convetions - start with "_". Then:

return View("~/Views/Shared/Blocks/_Name-of-your-view.cshtml", model);

This is because EPiServer is optimizing: and if it sees view with the same name as your block type - it *will* skip your controller and pass proxy class directly as model.

Okay. I understand now. What I had to do to fix this was what Valdis Iljuconoks mentioned and also, I had to go into episerver admin -> content type -> LearningMaterial -> settings and set the MVC template to the LearningMaterialBlockController.

Thanks for your help Valdis. You're a rock star.

I would suggest to do everything from the code. It will eliminate manual steps once you deploy your site to production.