Fixed #44 (Casting a int to a nullable int)

Author: StefH

src/System.Linq.Dynamic.Core/ExpressionParser.cs

@@ -1267,6 +1267,7 @@ Expression ParseTypeAccess(Type type)
         {
             int errorPos = _textParser.CurrentToken.Pos;
             _textParser.NextToken();
+
             if (_textParser.CurrentToken.Id == TokenId.Question)
             {
                 if (!type.GetTypeInfo().IsValueType || IsNullableType(type))
@@ -1280,23 +1281,36 @@ Expression ParseTypeAccess(Type type)
             bool shorthand = _textParser.CurrentToken.Id == TokenId.StringLiteral;
             if (_textParser.CurrentToken.Id == TokenId.OpenParen || shorthand)
             {
-                Expression[] args = shorthand
-                    ? new[] { ParseStringLiteral() }
-                    : ParseArgumentList();
+                Expression[] args = shorthand ? new[] { ParseStringLiteral() } : ParseArgumentList();
+
+                // If only 1 argument, and if the type is a Nullable, just make Nullable
+                if (args.Length == 1)
+                {
+                    Type argType = args[0].Type;
+
+                    if (type.GetTypeInfo().IsValueType && IsNullableType(type) && argType.GetTypeInfo().IsValueType)
+                    {
+                        return Expression.Convert(args[0], type);
+                    }
+                }
 
                 MethodBase method;
                 switch (FindBestMethod(type.GetConstructors(), args, out method))
                 {
                     case 0:
                         if (args.Length == 1)
                             return GenerateConversion(args[0], type, errorPos);
+
                         throw ParseError(errorPos, Res.NoMatchingConstructor, GetTypeName(type));
+
                     case 1:
                         return Expression.New((ConstructorInfo)method, args);
+
                     default:
                         throw ParseError(errorPos, Res.AmbiguousConstructorInvocation, GetTypeName(type));
                 }
             }
+
             _textParser.ValidateToken(TokenId.Dot, Res.DotOrOpenParenOrStringLiteralExpected);
             _textParser.NextToken();
 
@@ -1311,12 +1325,10 @@ static Expression GenerateConversion(Expression expr, Type type, int errorPos)
 
             if (exprType.GetTypeInfo().IsValueType && type.GetTypeInfo().IsValueType)
             {
-                if ((IsNullableType(exprType) || IsNullableType(type)) &&
-                    GetNonNullableType(exprType) == GetNonNullableType(type))
+                if ((IsNullableType(exprType) || IsNullableType(type)) && GetNonNullableType(exprType) == GetNonNullableType(type))
                     return Expression.Convert(expr, type);
 
-                if ((IsNumericType(exprType) || IsEnumType(exprType)) &&
-                    IsNumericType(type) || IsEnumType(type))
+                if ((IsNumericType(exprType) || IsEnumType(exprType)) && IsNumericType(type) || IsEnumType(type))
                     return Expression.ConvertChecked(expr, type);
             }
 

test/System.Linq.Dynamic.Core.Tests/EntitiesTests.Cast.cs

@@ -4,32 +4,48 @@ namespace System.Linq.Dynamic.Core.Tests
 {
     public partial class EntitiesTests
     {
-        // [Fact] https://github.com/StefH/System.Linq.Dynamic.Core/issues/44
+        // https://github.com/StefH/System.Linq.Dynamic.Core/issues/44
+        [Fact]
         public void Cast_To_nullableint()
         {
             // Arrange
             PopulateTestData(1, 0);
 
             // Act
-            var expectedResult = _context.Blogs.Select(b => (int?)b.BlogId);
-            var result = _context.Blogs.AsQueryable().Select("int?(BlogId)");
+            var expectedResult = _context.Blogs.Select(b => (int?)b.BlogId).Count();
+            var result = _context.Blogs.AsQueryable().Select("int?(BlogId)").Count();
 
             // Assert
-            Assert.Equal(expectedResult.ToArray(), result.ToDynamicArray<int?>());
+            Assert.Equal(expectedResult, result);
         }
 
-        // [Fact] https://github.com/StefH/System.Linq.Dynamic.Core/issues/44
+        [Fact]
+        public void Cast_To_nullablelong()
+        {
+            // Arrange
+            PopulateTestData(1, 0);
+
+            // Act
+            var expectedResult = _context.Blogs.Select(b => (long?)b.BlogId).Count();
+            var result = _context.Blogs.AsQueryable().Select("long?(BlogId)").Count();
+
+            // Assert
+            Assert.Equal(expectedResult, result);
+        }
+
+        // https://github.com/StefH/System.Linq.Dynamic.Core/issues/44
+        [Fact]
         public void Cast_To_newnullableint()
         {
             // Arrange
             PopulateTestData(1, 0);
 
             // Act
-            var expectedResult = _context.Blogs.Select(x => new { i = (int?)x.BlogId });
-            var result = _context.Blogs.AsQueryable().Select("new (int?(BlogId) as i)");
-           
+            var expectedResult = _context.Blogs.Select(x => new { i = (int?)x.BlogId }).Count();
+            var result = _context.Blogs.AsQueryable().Select("new (int?(BlogId) as i)").Count();
+
             //Assert
-            Assert.Equal(expectedResult.Count(), result.Count());
+            Assert.Equal(expectedResult, result);
         }
     }
 }

test/System.Linq.Dynamic.Core.Tests/QueryableTests.Count.cs

@@ -32,7 +32,7 @@ public void Count_Predicate()
 
             //Act
             int expected = queryable.Count(u => u.Income > 50);
-            int result = (queryable as IQueryable).Count("Income > 50");
+            int result = queryable.Count("Income > 50");
 
             //Assert
             Assert.Equal(expected, result);
@@ -48,7 +48,7 @@ public void Count_Predicate_WithArgs()
 
             //Act
             int expected = queryable.Count(u => u.Income > value);
-            int result = (queryable as IQueryable).Count("Income > @0", value);
+            int result = queryable.Count("Income > @0", value);
 
             //Assert
             Assert.Equal(expected, result);