EdgeService.cs

namespace MyClient.Foundation.Services
{
    using Sitecore.Data.Items;
    using Sitecore.ExperienceEdge.Connector.Abstraction.DirectPublishing;

    public class EdgeService : IEdgeService
    {
        private const string EdgePublishingTargetId = "{3013BEED-71CA-4DE3-A1D2-17DD871597F1}";

        /// <summary>
        /// This is confirmed to also be a singleton, thus this class is as well
        /// </summary>
        private readonly IItemPublishingManager itemPublishManager;

        public EdgeService(IItemPublishingManager itemPublishManager)
        {
            this.itemPublishManager = itemPublishManager;
        }

        /// <summary>
        /// During a publish to Edge, the Edge Connector must generate the rendered markup of a page. It does so by setting a "DummyHttpContext".
        /// We can leverage this fact to our advantage during rendering by requesting items that are only eligible for Edge publishing.
        /// This is useful within a Rendering Contents Resolver if additional items are needed to populate the JSON object. Each object can be
        /// checked for eligibility.
        /// </summary>
        public bool IsEdgePublishingContext()
        {
            var requestParams = Sitecore.Context.HttpContext?.Request?.Params;

            // the dummy request of the Edge Connector has a variety of properties that can be keyed on, but we chose requestParams
            if(requestParams == null)
            {
                return false;
            }

            return requestParams.Count == 0;
        }

        public Item GetEligibleRenderingItem(Item item)
        {
            if(item == null)
            {
                return null;
            }

            // if it is targeting a database other than web, just return the original item
            if (item.Database?.Name != "master")
            {
                return item;
            }

            // here is where we know it's targeting the master database, now we need to check if the Edge connector is generating the layout
            if (this.IsEdgePublishingContext())
            {
                // if so, we need to get the eligible version of the item, not just the latest version as it may have restrictions
                return this.itemPublishManager.GetPublishableVersion(item, new Sitecore.Data.ID(EdgePublishingTargetId), false);
            }
            
            return item;
        }
    }
}