Read double as float on SQL Server when precision is less than 25 (#2…

…5881)

Fixes #22572

src/EFCore.SqlServer/Storage/Internal/SqlServerDoubleTypeMapping.cs

@@ -4,6 +4,8 @@
 using System;
 using System.Data;
 using System.Data.Common;
+using System.Linq.Expressions;
+using System.Reflection;
 using Microsoft.EntityFrameworkCore.Storage;
 
 namespace Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal
@@ -16,6 +18,9 @@ namespace Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal
     /// </summary>
     public class SqlServerDoubleTypeMapping : DoubleTypeMapping
     {
+        private static readonly MethodInfo _getFloatMethod
+            = typeof(DbDataReader).GetRuntimeMethod(nameof(DbDataReader.GetFloat), new[] { typeof(int) })!;
+
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
         ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
@@ -73,6 +78,30 @@ protected override string GenerateNonNullSqlLiteral(object value)
                     : literal;
         }
 
+        /// <summary>
+        ///     The method to use when reading values of the given type. The method must be defined
+        ///     on <see cref="DbDataReader" /> or one of its subclasses.
+        /// </summary>
+        /// <returns> The method to use to read the value. </returns>
+        public override MethodInfo GetDataReaderMethod()
+            => Precision is <= 24 ? _getFloatMethod : base.GetDataReaderMethod();
+
+        /// <summary>
+        ///     Gets a custom expression tree for reading the value from the input data reader
+        ///     expression that contains the database value.
+        /// </summary>
+        /// <param name="expression"> The input expression, containing the database value. </param>
+        /// <returns> The expression with customization added. </returns>
+        public override Expression CustomizeDataReaderExpression(Expression expression)
+        {
+            if (Precision is <= 24)
+            {
+                expression = Expression.Convert(expression, typeof(double));
+            }
+
+            return base.CustomizeDataReaderExpression(expression);
+        }
+
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
         ///     the same compatibility standards as public APIs. It may be changed or removed without notice in

test/EFCore.SqlServer.FunctionalTests/BuiltInDataTypesSqlServerTest.cs

@@ -1693,6 +1693,45 @@ private static MappedScaledSeparatelyDataTypes CreateMappedScaledSeparatelyDataT
                 DecimalAsNumeric3 = 103m
             };
 
+        [ConditionalFact]
+        public virtual void Can_insert_and_read_back_double_types_with_precision()
+        {
+            using (var context = CreateContext())
+            {
+                context.Set<DoubleDataTypes>().Add(CreateDoubleDataTypes(77));
+
+                Assert.Equal(1, context.SaveChanges());
+            }
+
+            var parameters = DumpParameters();
+            Assert.Equal(
+                @"@p0='77'
+@p1='83.33000183105469' (Size = 25)
+@p2='83.30000305175781' (Size = 3)",
+                parameters,
+                ignoreLineEndingDifferences: true);
+
+            using (var context = CreateContext())
+            {
+                AssertDoubleDataTypes(context.Set<DoubleDataTypes>().Single(e => e.Id == 77), 77);
+            }
+        }
+
+        private static void AssertDoubleDataTypes(DoubleDataTypes entity, int id)
+        {
+            Assert.Equal(id, entity.Id);
+            Assert.Equal(83.3f, entity.Double3);
+            Assert.Equal(83.33f, entity.Double25);
+        }
+
+        private static DoubleDataTypes CreateDoubleDataTypes(int id)
+            => new()
+            {
+                Id = id,
+                Double3 = 83.3f,
+                Double25 = 83.33f
+            };
+
         [ConditionalFact]
         public virtual void Can_insert_and_read_back_all_mapped_data_types_with_precision_and_scale()
         {
@@ -2965,6 +3004,9 @@ public virtual void Columns_have_expected_data_types()
 BuiltInNullableDataTypesShadow.TestString ---> [nullable nvarchar] [MaxLength = -1]
 DateTimeEnclosure.DateTimeOffset ---> [nullable datetimeoffset] [Precision = 7]
 DateTimeEnclosure.Id ---> [int] [Precision = 10 Scale = 0]
+DoubleDataTypes.Double25 ---> [float] [Precision = 53]
+DoubleDataTypes.Double3 ---> [real] [Precision = 24]
+DoubleDataTypes.Id ---> [int] [Precision = 10 Scale = 0]
 EmailTemplate.Id ---> [uniqueidentifier]
 EmailTemplate.TemplateType ---> [int] [Precision = 10 Scale = 0]
 MappedDataTypes.BoolAsBit ---> [bit]
@@ -3599,6 +3641,14 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
                         b.Property(e => e.DecimalAsNumeric3).HasPrecision(3);
                     });
 
+                modelBuilder.Entity<DoubleDataTypes>(
+                    b =>
+                    {
+                        b.Property(e => e.Id).ValueGeneratedNever();
+                        b.Property(e => e.Double3).HasPrecision(3);
+                        b.Property(e => e.Double25).HasPrecision(25);
+                    });
+
                 modelBuilder.Entity<MappedPrecisionAndScaledSeparatelyDataTypes>(
                     b =>
                     {
@@ -4118,6 +4168,14 @@ protected class MappedScaledSeparatelyDataTypes
             public decimal DecimalAsNumeric3 { get; set; }
         }
 
+        protected class DoubleDataTypes
+        {
+            public int Id { get; set; }
+
+            public double Double3 { get; set; }
+            public double Double25 { get; set; }
+        }
+
         protected class MappedPrecisionAndScaledDataTypes
         {
             public int Id { get; set; }