[2.1.5] Query: Improve logic to find underlying property for projection

Issue: GroupJoin-DefaultIfEmpty aka left outer join introduced NullableExpression around the property which we fail to find hence we use wrong type mapping which expect int32 but we get back int16 from database

Resolves #13025

Author: smitpatel

src/EFCore.Relational/Extensions/RelationalExpressionExtensions.cs

@@ -89,6 +89,9 @@ public static IProperty FindProperty([NotNull] this Expression expression, [NotN
                     return columnReferenceExpression.Expression.FindProperty(targetType);
                 case AliasExpression aliasExpression:
                     return aliasExpression.Expression.FindProperty(targetType);
+                case NullableExpression nullableExpression
+                when !AppContext.TryGetSwitch("Microsoft.EntityFrameworkCore.Issue13025", out var isEnabled) || !isEnabled:
+                    return nullableExpression.Operand.FindProperty(targetType);
                 case UnaryExpression unaryExpression:
                     return unaryExpression.Operand.FindProperty(targetType);
                 case SqlFunctionExpression functionExpression:

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

@@ -3472,6 +3472,90 @@ public class MaumarEntity11818
 
         #endregion
 
+        #region Bug13025
+
+        [Fact]
+        public virtual void Find_underlying_property_after_GroupJoin_DefaultIfEmpty()
+        {
+            using (CreateDatabase13025())
+            {
+                using (var context = new MyContext13025(_options))
+                {
+                    var query = (from e in context.Employees
+                                 join d in context.EmployeeDevices
+                                    on e.Id equals d.EmployeeId into grouping
+                                 from j in grouping.DefaultIfEmpty()
+                                 select new Holder13025
+                                 {
+                                     Name = e.Name,
+                                     DeviceId = j.DeviceId
+                                 }).ToList();
+
+                }
+            }
+        }
+
+        public class Holder13025
+        {
+            public string Name { get; set; }
+            public int? DeviceId { get; set; }
+        }
+
+        private SqlServerTestStore CreateDatabase13025()
+        {
+            return CreateTestStore(
+                () => new MyContext13025(_options),
+                context =>
+                {
+                    context.AddRange(
+                        new Employee13025
+                        {
+                            Name = "Test1",
+                            Devices = new List<EmployeeDevice13025>
+                            {
+                                new EmployeeDevice13025
+                                {
+                                    DeviceId = 1,
+                                    Device = "Battery"
+                                }
+                            }
+                        });
+
+                    context.SaveChanges();
+                    ClearLog();
+                });
+        }
+
+        public class MyContext13025 : DbContext
+        {
+            public DbSet<Employee13025> Employees { get; set; }
+            public DbSet<EmployeeDevice13025> EmployeeDevices { get; set; }
+            public MyContext13025(DbContextOptions options)
+               : base(options)
+            {
+            }
+            protected override void OnModelCreating(ModelBuilder modelBuilder)
+            {
+            }
+        }
+        public class Employee13025
+        {
+            public int Id { get; set; }
+            public string Name { get; set; }
+            public ICollection<EmployeeDevice13025> Devices { get; set; }
+        }
+
+        public class EmployeeDevice13025
+        {
+            public int Id { get; set; }
+            public short DeviceId { get; set; }
+            public int EmployeeId { get; set; }
+            public string Device { get; set; }
+            public Employee13025 Employee { get; set; }
+        }
+
+        #endregion
+
         private DbContextOptions _options;
 
         private SqlServerTestStore CreateTestStore<TContext>(
@@ -3488,6 +3572,7 @@ private SqlServerTestStore CreateTestStore<TContext>(
                 context.Database.EnsureCreated();
                 contextInitializer?.Invoke(context);
             }
+
             return testStore;
         }