Query: Configure and use TypeMapping on DbFunction

- Add a convention which configures actual type mapping from store type on DbFunction
- While translating db function use the TypeMapping if available

Resolves #27954
Resolves #27524

src/EFCore.Relational/Metadata/Conventions/Infrastructure/RelationalConventionSetBuilder.cs

@@ -110,6 +110,7 @@ public override ConventionSet CreateConventionSet()
             typeof(ModelCleanupConvention));
         conventionSet.ModelFinalizingConventions.Add(new TableSharingConcurrencyTokenConvention(Dependencies, RelationalDependencies));
         conventionSet.ModelFinalizingConventions.Add(dbFunctionAttributeConvention);
+        conventionSet.ModelFinalizingConventions.Add(new ScalarDbFunctionTypeMappingConvention(Dependencies, RelationalDependencies));
         conventionSet.ModelFinalizingConventions.Add(tableNameFromDbSetConvention);
         conventionSet.ModelFinalizingConventions.Add(storeGenerationConvention);
         conventionSet.ModelFinalizingConventions.Add(new EntityTypeHierarchyMappingConvention(Dependencies, RelationalDependencies));

src/EFCore.Relational/Metadata/Conventions/ScalarDbFunctionTypeMappingConvention.cs

@@ -0,0 +1,62 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.EntityFrameworkCore.Metadata.Conventions;
+
+/// <summary>
+///     A convention that configures the store type to which a scalar function is mapped.
+/// </summary>
+/// <remarks>
+///     See <see href="https://aka.ms/efcore-docs-conventions">Model building conventions</see> and
+///     <see href="https://aka.ms/efcore-docs-database-functions">Database functions</see> for more information and examples.
+/// </remarks>
+public class ScalarDbFunctionTypeMappingConvention : IModelFinalizingConvention
+{
+    /// <summary>
+    ///     Creates a new instance of <see cref="ScalarDbFunctionTypeMappingConvention" />.
+    /// </summary>
+    /// <param name="dependencies">Parameter object containing dependencies for this convention.</param>
+    /// <param name="relationalDependencies"> Parameter object containing relational dependencies for this convention.</param>
+    public ScalarDbFunctionTypeMappingConvention(
+        ProviderConventionSetBuilderDependencies dependencies,
+        RelationalConventionSetBuilderDependencies relationalDependencies)
+    {
+        Dependencies = dependencies;
+        RelationalDependencies = relationalDependencies;
+    }
+
+    /// <summary>
+    ///     Dependencies for this service.
+    /// </summary>
+    protected virtual ProviderConventionSetBuilderDependencies Dependencies { get; }
+
+    /// <summary>
+    ///     Relational provider-specific dependencies for this service.
+    /// </summary>
+    protected virtual RelationalConventionSetBuilderDependencies RelationalDependencies { get; }
+
+    /// <inheritdoc />
+    public virtual void ProcessModelFinalizing(
+        IConventionModelBuilder modelBuilder,
+        IConventionContext<IConventionModelBuilder> context)
+    {
+        foreach (var function in modelBuilder.Metadata.GetDbFunctions())
+        {
+            ProcessDbFunction(function.Builder);
+        }
+    }
+
+    private void ProcessDbFunction(
+        IConventionDbFunctionBuilder dbFunctionBuilder)
+    {
+        var function = dbFunctionBuilder.Metadata;
+        if (!function.IsScalar
+            || function.StoreType == null)
+        {
+            return;
+        }
+
+        var typeMapping = ((IRelationalTypeMappingSource)Dependencies.TypeMappingSource).FindMapping(function.ReturnType, function.StoreType);
+        dbFunctionBuilder.HasTypeMapping(typeMapping);
+    }
+}

src/EFCore.Relational/Query/RelationalMethodCallTranslatorProvider.cs

@@ -81,14 +81,16 @@ public RelationalMethodCallTranslatorProvider(RelationalMethodCallTranslatorProv
                     arguments,
                     dbFunction.IsNullable,
                     argumentsPropagateNullability,
-                    method.ReturnType.UnwrapNullableType())
+                    method.ReturnType.UnwrapNullableType(),
+                    dbFunction.TypeMapping)
                 : _sqlExpressionFactory.Function(
                     dbFunction.Schema,
                     dbFunction.Name,
                     arguments,
                     dbFunction.IsNullable,
                     argumentsPropagateNullability,
-                    method.ReturnType.UnwrapNullableType());
+                    method.ReturnType.UnwrapNullableType(),
+                    dbFunction.TypeMapping);
         }
 
         return _plugins.Concat(_translators)

test/EFCore.Relational.Specification.Tests/Query/SimpleQueryRelationalTestBase.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
+using System.ComponentModel.DataAnnotations.Schema;
 using NameSpace1;
 
 namespace Microsoft.EntityFrameworkCore.Query
@@ -49,6 +51,56 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
                 mb.ToTable((string)null);
             }
         }
+
+        [ConditionalTheory]
+        [MemberData(nameof(IsAsyncData))]
+        public virtual async Task StoreType_for_UDF_used(bool async)
+        {
+            var contextFactory = await InitializeAsync<Context27954>();
+            using var context = contextFactory.CreateContext();
+
+            var date = new DateTime(2012, 12, 12);
+            var query1 = context.Set<MyEntity>().Where(x => x.SomeDate == date);
+            var query2 = context.Set<MyEntity>().Where(x => MyEntity.Modify(x.SomeDate) == date);
+
+            if (async)
+            {
+                await query1.ToListAsync();
+                await Assert.ThrowsAnyAsync<Exception>(() => query2.ToListAsync());
+            }
+            else
+            {
+                query1.ToList();
+                Assert.ThrowsAny<Exception>(() => query2.ToList());
+            }
+        }
+
+        protected class Context27954 : DbContext
+        {
+            public Context27954(DbContextOptions options)
+                : base(options)
+            {
+            }
+
+            public DbSet<MyEntity> MyEntities { get; set; }
+
+            protected override void OnModelCreating(ModelBuilder modelBuilder)
+            {
+                modelBuilder
+                    .HasDbFunction(typeof(MyEntity).GetMethod(nameof(MyEntity.Modify)))
+                    .HasName("ModifyDate")
+                    .HasStoreType("datetime")
+                    .HasSchema("dbo");
+            }
+        }
+
+        protected class MyEntity
+        {
+            public int Id { get; set; }
+            [Column(TypeName = "datetime")]
+            public DateTime SomeDate { get; set; }
+            public static DateTime Modify(DateTime date) => throw new NotSupportedException();
+        }
     }
 }
 

test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.cs

@@ -391,4 +391,22 @@ WHERE [c].[SomeNullableDateTime] IS NULL
 ) AS [t0] ON [p].[Id] = [t0].[ParentId]
 WHERE [t0].[SomeOtherNullableDateTime] IS NOT NULL");
     }
+
+    public override async Task StoreType_for_UDF_used(bool async)
+    {
+        await base.StoreType_for_UDF_used(async);
+
+        AssertSql(
+            @"@__date_0='2012-12-12T00:00:00.0000000' (DbType = DateTime)
+
+SELECT [m].[Id], [m].[SomeDate]
+FROM [MyEntities] AS [m]
+WHERE [m].[SomeDate] = @__date_0",
+                //
+                @"@__date_0='2012-12-12T00:00:00.0000000' (DbType = DateTime)
+
+SELECT [m].[Id], [m].[SomeDate]
+FROM [MyEntities] AS [m]
+WHERE [dbo].[ModifyDate]([m].[SomeDate]) = @__date_0");
+    }
 }