It might be better to use Relationships for this instead of Examine. You'd have to hook into the save/publish event and add a relationship between the news article node and the picked categories nodes.

Then you could search for all relationships of this type to know which categories to display.

If you do this though, remember to hook into the delete/unpublish events to remove the relationships for the given nodes :-)

You could also try nuPickers https://our.umbraco.com/packages/backoffice-extensions/nupickers/. It is a collection of pickers that can be powered by different data sources. One of the options is the Lucene DropDown Picker. I use the Enum pickers and DotNet pickers a lot, but have not personally used the Lucene pickers.

The only thing negative I can think to say about this is that it hasn't yet been ported to Umbraco 8 yet.

using Umbraco.Core;
using Umbraco.Core.Composing;
using Umbraco.Core.Services.Implement;
using Umbraco.Core.Logging;
using Umbraco.Core.Models;
using Umbraco.Core.Services;
using System.Linq;
using Umbraco.Core.Events;
using Umbraco.Core.Models.PublishedContent;
using System.Collections.Generic;

namespace ProjectX.Core.Components
{
    class CheckTagsOnArticlesComponent : IComponent
    {

        private readonly IRelationService _relationService;

        // register our component with Umbraco using a Composer

        public CheckTagsOnArticlesComponent(IRelationService relationService)
        {
            _relationService = relationService;
        }

        public void Initialize()
        {
            // subscribe to content service published event
            ContentService.Published += ContentService_Published;

        }

        // initialize: runs once when Umbraco starts


        private void ContentService_Published(IContentService sender, ContentPublishedEventArgs e)
        {

            foreach (var node in e.PublishedEntities)
            {
                if (node.ContentType.Alias.ToLowerInvariant() == "stories")
                {
                    // Get the Id of the node that was published
                    var id = node.Id;

                    if (node.HasProperty("theme"))
                    {

                    }


                    var relationType = _relationService.GetRelationTypeByAlias("relateStoryToTheme");
                    if (relationType == null) return;

                    foreach (var entity in e.PublishedEntities.Where(x => x.Id != node.Id))
                    {
                        if (!_relationService.AreRelated(node.Id, entity.Id))
                        {
                            _relationService.Relate(node.Id, entity.Id, relationType);
                        }
                    }

               }
            }


        }


            // terminate: runs once when Umbraco stops
            public void Terminate()
            {
                // do something when Umbraco terminates
            }

    }
}

So, I've spent most of the afternoon working on this and I think it's getting there, but I'm up against it with hours so if anyone could point me in a more complete solution, that would really be appreciated.

Just now, it hits the if node alias is stories which is a start. but then I need to create the relationship between the story and the multinode tree picker values which are with an alias of theme.

Just now node.HasProperty("theme") returns true then bombs out at var relationType

O.

Soz for briefness, but if you wanna BYO, see if this helps as well. 🙂
http://blog.aabech.no/archive/building-a-spell-checker-for-search-in-umbraco/

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