Merge pull request #54 from BlaiseD/master

Fix for Issue #53 - InvalidOperationException mapping a string with Plus (+) operator

Author: BlaiseD

Directory.Build.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <Authors>Jimmy Bogard</Authors>
     <LangVersion>latest</LangVersion>
-    <VersionPrefix>3.0.5</VersionPrefix>
+    <VersionPrefix>3.0.6-preview01</VersionPrefix>
     <WarningsAsErrors>true</WarningsAsErrors>
     <NoWarn>$(NoWarn);1701;1702;1591</NoWarn>
   </PropertyGroup>

src/AutoMapper.Extensions.ExpressionMapping/XpressionMapperVisitor.cs

@@ -146,11 +146,15 @@ Expression DoVisitBinary(Expression newLeft, Expression newRight, Expression con
                             newLeft,
                             newRight,
                             node.IsLiftedToNull,
-                            Expression.MakeBinary(node.NodeType, newLeft, newRight).Method
+                            TypesChanged()
+                                ? Expression.MakeBinary(node.NodeType, newLeft, newRight).Method
+                                : node.Method
                         );
                 }
 
                 return node;
+
+                bool TypesChanged() => newLeft.Type != node.Left.Type || newRight.Type != node.Right.Type;
             }
         }
 

tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/XpressionMapperTests.cs

@@ -176,6 +176,20 @@ public void Map_object_type_change_again()
             Assert.True(users.Count == 0);
         }
 
+        [Fact]
+        public void Uses_the_correct_Add_expression_when_mapping_string_plus_operator()
+        {
+            //Arrange
+            Expression<Func<UserModel, bool>> selection = s => s.FullName + "FFF" == "";
+
+            //Act
+            Expression<Func<User, bool>> selectionMapped = mapper.MapExpression<Expression<Func<User, bool>>>(selection);
+            List<User> users = Users.Where(selectionMapped).ToList();
+
+            //Assert
+            Assert.True(users.Count == 0);
+        }
+
         [Fact]
         public void Map__object_including_child_and_grandchild()
         {