Updated Suggested Types Rules for CMS 12

CustomContentRecommendation.cs

using EPiServer.Cms.Shell.UI.Rest;
using EPiServer.Core;
using EPiServer.DataAbstraction;
using EPiServer.ServiceLocation;
using EPiServer;
using System.Collections.Generic;
using CodeArt.Web.Models.Pages;

namespace CodeArt.Web.Business.SuggestedTypes
{
    [ServiceConfiguration(typeof(IContentTypeAdvisor))]
    public class CustomContentRecommendations : IContentTypeAdvisor
    {
        public IContentRepository repo { get; set; }

        public CustomContentRecommendations(IContentRepository repo)
        {
            this.repo = repo;
        }

        //Add custom recommendations according to rules
        public IEnumerable<int> GetSuggestions(IContent parent, bool contentFolder, IEnumerable<string> requestedTypes)
        {

            var startpage=repo.Get<StartPage>(ContentReference.StartPage);

            if (startpage.SuggestedTypes != null)
            {
                foreach(var r in startpage.SuggestedTypes)
                {
                    if(r.ParentContentType == parent.ContentTypeID.ToString() || r.ParentContent.CompareToIgnoreWorkID(parent.ContentLink))
                    {
                        if (r.ForThisContentFolder == contentFolder)
                        {
                            var types = r.TypesToSuggest.Split(',');
                            foreach (var t in types)
                            {
                                yield return int.Parse(t);
                            }
                        }
                    }
                }
            }

        }
    }
}

StartPage.cs

    public class StartPage : ListPage
    {
    ...
    
        //In this example the suggested types rules are added on the Site Settings tab of the StartPage - but it could also be on a custom Settings element.
        [Display(Name = "Suggested Types Rules" , GroupName = Globals.TAB_SITESETTINGS, Order = 110)]
        public virtual IList<SuggestedTypesBlock> SuggestedTypes { get; set;}
    
    ...
    }

SuggestedTypeRuleBlock.cs

using System.ComponentModel.DataAnnotations;
using EPiServer.Core;
using EPiServer.DataAbstraction;
using EPiServer.DataAnnotations;
using EPiServer.Shell.ObjectEditing;
using System.Collections.Generic;
using EPiServer.ServiceLocation;
using System.Linq;

namespace CodeArt.Web.Models.Blocks
{
    [ContentType(DisplayName = "Suggested Types Rule", GUID = "AE86837F-65BD-4FEA-B007-3B2224DAD53E", Description = "", AvailableInEditMode = false)]
    public class SuggestedTypesBlock : BlockData
    {

        [Display(Order = 10, Name ="Parent Content Type")]
        [SelectOne(SelectionFactoryType = typeof(ContentTypesSelectionFactory))]
        public virtual string ParentContentType { get; set; }

        [Display(Order =20, Name = "Parent Content")]
        public virtual ContentReference ParentContent { get; set; }

        [Display(Order = 30, Description = "", Name = "In 'For this Content' folder?")]
        public virtual bool ForThisContentFolder { get; set; }

        [Display(Order = 40, Description = "", Name ="Types to suggest")]
        [Required]
        [SelectMany(SelectionFactoryType = typeof(ContentTypesSelectionFactory))]
        public virtual string TypesToSuggest { get; set; }

    }

    public class ContentTypesSelectionFactory : ISelectionFactory
    {
        public IEnumerable<ISelectItem> GetSelections(ExtendedMetadata metadata)
        {
            var typerepo = ServiceLocator.Current.GetInstance<IContentTypeRepository>();
            var lst = typerepo.List().Where(t => t.IsAvailable).Select(t => new SelectItem() { Text = t.LocalizedName ?? t.DisplayName ?? t.Name, Value = t.ID }).ToArray();
            return lst;
        }
    }
    
}