HooksDiscovery.cs

using System;
using System.Collections.Generic;
using System.Linq;
using JsonApiDotNetCore.Internal;
using JsonApiDotNetCore.Models;
using Microsoft.Extensions.DependencyInjection;

namespace JsonApiDotNetCore.Hooks
{
    /// <summary>
    /// The default implementation for IHooksDiscovery
    /// </summary>
    public class HooksDiscovery<TEntity> : IHooksDiscovery<TEntity> where TEntity : class, IIdentifiable
    {
        private readonly ResourceHook[] _allHooks;
        private readonly ResourceHook[] _databaseValuesAttributeAllowed =
        {
            ResourceHook.BeforeUpdate,
            ResourceHook.BeforeUpdateRelationship,
            ResourceHook.BeforeDelete
        };

        /// <inheritdoc/>
        public ResourceHook[] ImplementedHooks { get; private set; }
        public ResourceHook[] DatabaseValuesEnabledHooks { get; private set; }
        public ResourceHook[] DatabaseValuesDisabledHooks { get; private set; }

        public HooksDiscovery(IServiceProvider provider)
        {
            _allHooks = Enum.GetValues(typeof(ResourceHook))
                            .Cast<ResourceHook>()
                            .Where(h => h != ResourceHook.None)
                            .ToArray();
            using (var scope = provider.CreateScope())
            {
                var container = scope.ServiceProvider.GetService(typeof(ResourceDefinition<TEntity>));
                if (container == null)
                    return;
                DiscoverImplementedHooksForModel(container.GetType());
            }
        }

        /// <summary>
        /// Discovers the implemented hooks for a model.
        /// </summary>
        /// <returns>The implemented hooks for model.</returns>
        void DiscoverImplementedHooksForModel(Type containerType)
        {
            var implementedHooks = new List<ResourceHook>();
            var enabledHooks = new List<ResourceHook>() { ResourceHook.BeforeImplicitUpdateRelationship } ;
            var disabledHooks = new List<ResourceHook>();
            if (containerType != null)
            {
                foreach (var hook in _allHooks)
                {
                    var method = containerType.GetMethod(hook.ToString("G"));
                    implementedHooks.Add(hook);
                    var attr = method.GetCustomAttributes(true).OfType<LoadDatabaseValues>().SingleOrDefault();
                    if (attr != null)
                    {
                        if (!_databaseValuesAttributeAllowed.Contains(hook))
                        {
                            throw new JsonApiSetupException($"DatabaseValuesAttribute cannot be used on hook" +
                                $"{hook.ToString("G")} in resource definition  {containerType.Name}");
                        }
                        var targetList = attr.value ? enabledHooks : disabledHooks;
                        targetList.Add(hook);
                    }
                }

            }
            ImplementedHooks = implementedHooks.ToArray();
            DatabaseValuesDisabledHooks = disabledHooks.ToArray();
            DatabaseValuesEnabledHooks = enabledHooks.ToArray();

        }
    }
}