Use more effective EF hook to register our custom provider

src/EntityFrameworkCore.Projections/Infrastructure/Internal/CustomQueryTranslationPreprocessorFactory.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Text;
+using System.Threading.Tasks;
+using EntityFrameworkCore.Projections.Services;
+using Microsoft.EntityFrameworkCore.Query;
+
+namespace EntityFrameworkCore.Projections.Infrastructure.Internal
+{
+    public class CustomQueryTranslationPreprocessorFactory : IQueryTranslationPreprocessorFactory
+    {
+        readonly IQueryTranslationPreprocessorFactory _decoratedFactory;
+        readonly QueryTranslationPreprocessorDependencies _queryTranslationPreprocessorDependencies;
+        readonly ProjectableExpressionReplacer _projectableExpressionReplacer = new();
+
+        public CustomQueryTranslationPreprocessorFactory(IQueryTranslationPreprocessorFactory decoratedFactory, QueryTranslationPreprocessorDependencies queryTranslationPreprocessorDependencies)
+        {
+            _decoratedFactory = decoratedFactory;
+            _queryTranslationPreprocessorDependencies = queryTranslationPreprocessorDependencies;
+        }
+
+        public QueryTranslationPreprocessor Create(QueryCompilationContext queryCompilationContext) 
+            => new CustomQueryTranslationPreprocessor(_queryTranslationPreprocessorDependencies, queryCompilationContext, _projectableExpressionReplacer);
+    }
+
+    public class CustomQueryTranslationPreprocessor : QueryTranslationPreprocessor
+    {
+        readonly ProjectableExpressionReplacer _projectableExpressionReplacer;
+
+        public CustomQueryTranslationPreprocessor(QueryTranslationPreprocessorDependencies dependencies, QueryCompilationContext queryCompilationContext, ProjectableExpressionReplacer projectableExpressionReplacer) : base(dependencies, queryCompilationContext)
+        {
+            _projectableExpressionReplacer = projectableExpressionReplacer;
+        }
+
+        public override Expression Process(Expression query) 
+            => base.Process(_projectableExpressionReplacer.Visit(query));
+    }
+}

src/EntityFrameworkCore.Projections/Infrastructure/Internal/ProjectionOptionsExtension.cs

@@ -2,8 +2,10 @@
 using Microsoft.EntityFrameworkCore.Query;
 using Microsoft.EntityFrameworkCore.Query.Internal;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -22,23 +24,35 @@ namespace EntityFrameworkCore.Projections.Infrastructure.Internal
         [System.Diagnostics.CodeAnalysis.SuppressMessage("Usage", "EF1001:Internal EF Core API usage.", Justification = "Needed")]
         public void ApplyServices(IServiceCollection services)
         {
-            var queryCompilerRegistration = services.FirstOrDefault(x => x.ServiceType == typeof(IQueryCompiler));
+            static object CreateTargetInstance(IServiceProvider services, ServiceDescriptor descriptor)
-            if (queryCompilerRegistration?.ImplementationType is null)
             {
-                throw new InvalidOperationException("No queryCompiler is configured yet. Please make sure to configure a database provider first"); ;
+                if (descriptor.ImplementationInstance is not null)
+                    return descriptor.ImplementationInstance;
+
+                if (descriptor.ImplementationFactory is not null)
+                    return descriptor.ImplementationFactory(services);
+
+                Debug.Assert(descriptor.ImplementationType is not null);
+
+                return ActivatorUtilities.GetServiceOrCreateInstance(services, descriptor.ImplementationType!);
             }
 
-            // Ensure that we can still resolve this queryCompiler
+            var targetDescriptor = services.FirstOrDefault(x => x.ServiceType == typeof(IQueryTranslationPreprocessorFactory));
-            services.Add(new ServiceDescriptor(queryCompilerRegistration.ImplementationType, queryCompilerRegistration.ImplementationType, queryCompilerRegistration.Lifetime));
+            if (targetDescriptor is null)
-            services.Remove(queryCompilerRegistration);
+            {
+                throw new InvalidOperationException("No QueryTranslationPreprocessorFactory is configured yet. Please make sure to configure a database provider first"); ;
+            }
 
-            services.Add(new ServiceDescriptor(
+            var decoratorObjectFactory = ActivatorUtilities.CreateFactory(typeof(CustomQueryTranslationPreprocessorFactory), new [] { targetDescriptor.ServiceType });
-                typeof(IQueryCompiler),
+
-                serviceProvider => new WrappedQueryCompiler((IQueryCompiler)serviceProvider.GetRequiredService(queryCompilerRegistration.ImplementationType)),
+            services.Replace(ServiceDescriptor.Describe(
-                queryCompilerRegistration.Lifetime
+                targetDescriptor.ServiceType,
+                serviceProvider => decoratorObjectFactory(serviceProvider, new[] { CreateTargetInstance(serviceProvider, targetDescriptor) }),
+                targetDescriptor.Lifetime
             ));
         }
 
+
         public void Validate(IDbContextOptions options)
         {
         }

src/EntityFrameworkCore.Projections/Infrastructure/Internal/WrappedQueryCompiler.cs

@@ -1,41 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
-using EntityFrameworkCore.Projections.Services;
-using Microsoft.EntityFrameworkCore.Query;
-using Microsoft.EntityFrameworkCore.Query.Internal;
-
-namespace EntityFrameworkCore.Projections.Infrastructure.Internal
-{
-    [System.Diagnostics.CodeAnalysis.SuppressMessage("Usage", "EF1001:Internal EF Core API usage.", Justification = "Needed")]
-    public sealed class WrappedQueryCompiler : IQueryCompiler
-    {
-        readonly ProjectableExpressionReplacer _projectionExpressionReplacer = new();
-        readonly IQueryCompiler _queryCompiler;
-
-        public WrappedQueryCompiler(IQueryCompiler queryCompiler)
-        {
-            _queryCompiler = queryCompiler;
-        }
-
-        public Func<QueryContext, TResult> CreateCompiledAsyncQuery<TResult>(Expression query)
-            => _queryCompiler.CreateCompiledAsyncQuery<TResult>(PatchQuery(query));
-
-        public Func<QueryContext, TResult> CreateCompiledQuery<TResult>(Expression query)
-            => _queryCompiler.CreateCompiledQuery<TResult>(PatchQuery(query));
-
-        public TResult Execute<TResult>(Expression query)
-            => _queryCompiler.Execute<TResult>(PatchQuery(query));
-
-        public TResult ExecuteAsync<TResult>(Expression query, CancellationToken cancellationToken)
-            => _queryCompiler.ExecuteAsync<TResult>(PatchQuery(query), cancellationToken);
-
-        Expression PatchQuery(Expression expression)
-            => _projectionExpressionReplacer.Visit(expression);
-        
-    }
-}