DropDownList Category Picker in Episerver 7

Looking around these two posts helped me to find what I think is the best way:

• Episerver 7: Configuring editors for your properties by Linus Ekström
• A filtered page reference property by Joel Abrahamsson

In my case I needed the children and grandchildren of a configured root category as possible items.

namespace Krompaco.Project.Site
{
    using System.Collections.Generic;
    using EPiServer.DataAbstraction;
    using EPiServer.Shell.ObjectEditing;

    public class CategorySelectionFactory : ISelectionFactory
    {
        public IEnumerable<ISelectItem> GetSelections(ExtendedMetadata metadata)
        {
            var list = new List<SelectItem>();
            var root = Category.Find(yourIdInteger);

            foreach (Category country in root.Categories)
            {
                list.Add(new SelectItem
                  {
                     Text = country.LocalizedDescription.ToUpper(),
                     Value = country.ID.ToString()
                  });

                foreach (Category region in country.Categories)
                {
                    list.Add(new SelectItem
                      {
                        Text = region.LocalizedDescription,
                        Value = region.ID.ToString()
                      });
                }
            }

            return list;
        }
    }
}

Then you need to do this to make the UIHint mean something. Seems like there are problems having an int TargetType but I can live with having the property stored as a string.

namespace Krompaco.Project.Site
{
    using System;
    using System.Collections.Generic;
    using EPiServer.Shell.ObjectEditing;
    using EPiServer.Shell.ObjectEditing.EditorDescriptors;

    [EditorDescriptorRegistration(
        TargetType = typeof(string),
        UIHint = "project-category-select")]
    public class CategorySelector : EditorDescriptor
    {
        public override void ModifyMetadata(ExtendedMetadata metadata, IEnumerable<Attribute> attributes)
        {
            SelectionFactoryType = typeof(CategorySelectionFactory);

            // If on 7.0 and not 7.1 this has a slightly different syntax (more dots)
            ClientEditingClass = "epi-cms/contentediting/editors/SelectionEditor";

            base.ModifyMetadata(metadata, attributes);
        }
    }
}

Then just decorate properties with the same UIHint like this:

[UIHint("project-category-select")]
[Display(
  Name = "Primary category",
  GroupName = SystemTabNames.Content,
  Order = 900)]
public virtual string PrimaryCategoryId { get; set; }

In Edit Mode you'll then get a sleek DropDownList like this.