From a6efe9285111c8d76abf58764ab62a2c29dee1d0 Mon Sep 17 00:00:00 2001
From: Jason Webb <jason.webb@leadventure.com>
Date: Fri, 8 Nov 2024 15:08:00 -0700
Subject: [PATCH] Moved caching factory out of the constructors of CommandBus
 and QueryBus as it will be optional. Added some caching configuration
 validation.

---
 .../Commands/CommandBus.cs                       |  8 +++++---
 .../InvalidCacheException.cs                     | 16 ++++++++++++++++
 .../Queries/QueryBus.cs                          |  8 +++++---
 3 files changed, 26 insertions(+), 6 deletions(-)
 create mode 100644 Src/RCommon.ApplicationServices/InvalidCacheException.cs

diff --git a/Src/RCommon.ApplicationServices/Commands/CommandBus.cs b/Src/RCommon.ApplicationServices/Commands/CommandBus.cs
index 208881a..6e8b0f1 100644
--- a/Src/RCommon.ApplicationServices/Commands/CommandBus.cs
+++ b/Src/RCommon.ApplicationServices/Commands/CommandBus.cs
@@ -45,17 +45,16 @@ public class CommandBus : ICommandBus
         private readonly IServiceProvider _serviceProvider;
         private readonly IValidationService _validationService;
         private readonly IOptions<CqrsValidationOptions> _validationOptions;
-        private readonly ICacheService _cacheService;
+        private ICacheService _cacheService;
         private readonly CachingOptions _cachingOptions;
 
         public CommandBus(ILogger<CommandBus> logger, IServiceProvider serviceProvider, IValidationService validationService, 
-            IOptions<CqrsValidationOptions> validationOptions, IOptions<CachingOptions> cachingOptions, ICommonFactory<ExpressionCachingStrategy, ICacheService> cacheFactory)
+            IOptions<CqrsValidationOptions> validationOptions, IOptions<CachingOptions> cachingOptions)
         {
             _logger = logger;
             _serviceProvider = serviceProvider;
             _validationService = validationService;
             _validationOptions = validationOptions;
-            _cacheService = cacheFactory.Create(ExpressionCachingStrategy.Default);
             _cachingOptions = cachingOptions.Value;
         }
 
@@ -134,6 +133,9 @@ private CommandExecutionDetails GetCommandExecutionDetails(Type commandType)
         {
             if (_cachingOptions.CachingEnabled && _cachingOptions.CacheDynamicallyCompiledExpressions)
             {
+                var cachingFactory = _serviceProvider.GetService<ICommonFactory<ExpressionCachingStrategy, ICacheService>>();
+                Guard.Against<InvalidCacheException>(cachingFactory == null, "We could not properly inject the caching factory: 'ICommonFactory<ExpressionCachingStrategy, ICacheService>>' into the CommandBus");
+                _cacheService = cachingFactory.Create(ExpressionCachingStrategy.Default);
                 return _cacheService.GetOrCreate(CacheKey.With(GetType(), commandType.GetCacheKey()), () => this.BuildCommandDetails(commandType));
             }
             return this.BuildCommandDetails(commandType);
diff --git a/Src/RCommon.ApplicationServices/InvalidCacheException.cs b/Src/RCommon.ApplicationServices/InvalidCacheException.cs
new file mode 100644
index 0000000..9028134
--- /dev/null
+++ b/Src/RCommon.ApplicationServices/InvalidCacheException.cs
@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RCommon.ApplicationServices
+{
+    public class InvalidCacheException : GeneralException
+    {
+        public InvalidCacheException(string message):base(message)
+        {
+            
+        }
+    }
+}
diff --git a/Src/RCommon.ApplicationServices/Queries/QueryBus.cs b/Src/RCommon.ApplicationServices/Queries/QueryBus.cs
index 868735b..c55bff3 100644
--- a/Src/RCommon.ApplicationServices/Queries/QueryBus.cs
+++ b/Src/RCommon.ApplicationServices/Queries/QueryBus.cs
@@ -49,17 +49,16 @@ private class HandlerFuncMapping
         private readonly IValidationService _validationService;
         private readonly IOptions<CqrsValidationOptions> _validationOptions;
         private readonly CachingOptions _cachingOptions;
-        private readonly ICacheService _cacheService;
+        private ICacheService _cacheService;
 
         public QueryBus(ILogger<QueryBus> logger, IServiceProvider serviceProvider, IValidationService validationService,
-            IOptions<CqrsValidationOptions> validationOptions, IOptions<CachingOptions> cachingOptions, ICommonFactory<ExpressionCachingStrategy, ICacheService> cacheFactory)
+            IOptions<CqrsValidationOptions> validationOptions, IOptions<CachingOptions> cachingOptions)
         {
             _logger = logger;
             _serviceProvider = serviceProvider;
             _validationService = validationService;
             _validationOptions = validationOptions;
             _cachingOptions = cachingOptions.Value;
-            _cacheService = cacheFactory.Create(ExpressionCachingStrategy.Default);
         }
 
         public async Task<TResult> DispatchQueryAsync<TResult>(IQuery<TResult> query, CancellationToken cancellationToken = default)
@@ -92,6 +91,9 @@ private HandlerFuncMapping GetHandlerFuncMapping(Type queryType)
         {
             if (_cachingOptions.CachingEnabled && _cachingOptions.CacheDynamicallyCompiledExpressions)
             {
+                var cachingFactory = _serviceProvider.GetService<ICommonFactory<ExpressionCachingStrategy, ICacheService>>();
+                Guard.Against<InvalidCacheException>(cachingFactory == null, "We could not properly inject the caching factory: 'ICommonFactory<ExpressionCachingStrategy, ICacheService>>' into the QueryBus");
+                _cacheService = cachingFactory.Create(ExpressionCachingStrategy.Default);
                 return _cacheService.GetOrCreate(CacheKey.With(GetType(), queryType.GetCacheKey()), 
                     () => this.BuildHandlerFuncMapping(queryType));
             }